Recommended Handlebar Specs For 2020 MX Machines

When it comes to handlebars I am a pain in the ass. The height, width, rise, and position is very important to me between each bike that I test. I find that you can’t run the same handlebar bend on every bike, even though I like a bend on one bike, sometimes it doesn’t feel as good on another. Every bike has a different rider triangle so you must adapt to different bar bends if you change motorcycle brands. As the years progress, dirt bikes evolve as well as their dimensions so don’t be that rider who sticks with a Honda High bend that you ran back in 1997. As you may have heard in my “Handlebar 101” podcast (show #70), if the bar feels too low (height), you should try to get the bar height from your bar mounts and not the handlebar itself. Getting the height from your bar mounts allows you to keep proper technique (position) through corners (where most of the time is made up on a track). This article was a big hit last year and by the shear number of emails I get about handlebars, I wanted to update some bends for 2020. Here are some of my favorite bar bends right here for 2020 as well as a recommendation on bar/bar mount heights for different sized riders.  

As you will notice most of these handlebars on this list are Pro Taper and Renthal. This doesn’t mean that I am trying to sell you on these handlebar brands. This is just what I personally like myself and should be taken as such. If you like another bar brand, that is fine, simply look at the dimension of the preferred handlebar and try to mimic that dimension to your favorite handlebar company. There are tons of handlebar companies out there, but for me, Renthal and Pro Taper are the bars that I prefer. Again as always for testing purposes, I tried a wide range of handlebars in my shootout so go give that podcast a listen when you can (Show #70). There are some great options out there. Again….This doesn’t mean other handlebars are crap. For transparency reasons, I am letting you know that these are the companies I prefer. I receive ZERO dollars from Renthal or Pro Taper.

• We are using 2020 models for reference, but if you have an older model and are concerned on which handlebar to run please feel free to email me at kris@keeferinctesting.com. 

• All Dimensions are in (MM). 

2020 HONDA CRF 450R/250R:

Notes: The stock bar bend on the 2019/2020 Honda CRF 450R/250R has finally been updated to a bend that is lower and flatter than previous years. This bend is actually quite good and we usually leave the stock Renthal handlebar on the Honda. If you think you would like more flex you can try the optional bar bend below.  

Preferred: Stock Renthal 839 FatBar (W)802 (H)91 (R)52 (S)51 

Optional For More Flex: Pro Taper EVO SX Race (W)800 (H)87 (R)54.5 (S)54

Optional For 6’0-6’2: Factory Suzuki (W) 800 (H)92 (R)62 (S)47

Bar Mount Height: Stock 

2020 YAMAHA YZ450F/250F:

Notes: Yamaha also did a good job on creating a bar that is fairly neutral for different sized riders, it’s just too bad their seat and footage height is all screwed up for taller riders. It’s lower height seems to fit a wide variety of riders (5’8-6’0), but taller riders may want to put the bar mounts in forward hole/back position.  

Preferred: Pro Taper EVO SX Race (W)800 (H)87 (R)54.5 (S)54

Optional 6’0-6’2: Renthal Fatbar 602 bend (W)801 (H)89 (R)59 (S)56

Bar Mount Height: Stock 

2020 KAWASAKI KX450/250: 

Notes: 7/8 lives on! Kawasaki managed to keep the good ol’ 971 Renthal 7/8 bars, which are pretty damn good! I like a 7/8 bar and I actually stick with the 7/8 theme if I can. The 7/8 bar does bend a little easier, but you get a lot of flex when the track gets rough. If you’re an aggressive rider who likes a little more positive steering than go to a 1-1/8 handlebar for increased stiffness. 

Preferred: Renthal 7/8 983 bend (Villopoto/Stewart) (W)808 (H)95 (R)58 (S)55

Oversize Crossbar Option: Pro Taper Fuzion Henry/Reed (W)800 (H)92 (R)66 (R)40 (S)55

Optional For 6’0-6’2: Pro Taper EVO Factory Suzuki (W) 800 (H)92 (R)62 (S)47

Bar Mount Height: Stock

2020 SUZUKI RM-Z450/250:

Notes: The stock Suzuki bend has some sweep to it, which makes the bike feel small at times. I prefer to open the cockpit up a little. 

Preferred: Pro Taper EVO SX Race bend (W)800 (H)87 (R)54.5 (S)54

Optional: ODI Podium Flight CountryBoy bend (W)803 (H)92 (R)56 (S)52

Optional For 6’0-6’2: Pro Taper EVO Factory Suzuki (W) 800 (H)92 (R)62 (S)47

Bar Mount Height: Stock

2020 HUSQVARNA FC450/250:

Notes: Husqvarna comes with a very low bend and that fits the ergos of this bike, but the width of the bar is too long. I actually like the stock handlebar bend on the Husqvarna, however I cut the handlebar down to 803mm, which really helps the character of the Husqvarna when leaning into corners. 

Preferred: Stock Pro Taper EVO handlebar cut to 803mm (W)811 (H)80 (R)39.5 (S)51

Optional: Pro Taper EVO Carmichael bend (W)800 (H)77 (R)40 (S)55

Optional For 6’0-6’2: Pro Taper EVO Factory Suzuki (W) 800 (H)92 (R)62 (S)47

Bar Mount Height: Plus 5mm 

2020 KTM 450SX-F/250SX-F:

Notes: The stock bar bend shape on the orange brigade is also decent, but it’s too stiff and long. If you don’t think it is too stiff, you can simply cut the bar to 803mm and run it! 

Preferred: Renthal 821 bend cut to 803mm (W)813 (H)78 (R)42 (S)54

Optional: Pro Taper EVO Husqvarna Stock cut to 803mm (W) 811 (H)77 (R)40 (S)55

Optional For 6’0-6’2: Pro Taper EVO Factory Suzuki (W) 800 (H)92 (R)62 (S)47

Bar Mount Height: Plus 5mm

Fastway Air EXT Foot Pegs

Fastway Air EXT pegs are on a mission to reduce ankle injuries, or at least limit the severity when an impact goes wrong. The basic idea is a wide but fairly conventional 2024 billet aluminum footpeg with a teardrop-shaped sort of heel peg welded to the rear of the normal peg. The teardrop ankle-saving portion isn’t welded at the same level as the footpeg however. The contact point is lower than the surface of the peg, but the patented height, traction, and camber (tilt) adjustability, is fully customizable. The idea being that you never feel the Air EXT pegs until you suffer an extreme landing that puts excessive loads on your feet and/or ankles. The Universal Collar System (UCS) lets you customize your mount in either the stock or lowered positions on most bikes – simply by reversing the collar. Fastway’s patented replaceable traction cleat system allows you to customize the shape and traction level of your foot bed as well.

The reality is that you do feel the Air EXT’s rear portion fairly often on the track, but I only felt it in positive ways. No question, when you land short or long, your feet, ankles and even knees would be smiling if they had lips. Impacts that clank the suspension hard enough to hurt your ears don’t bother my 42 year old ankles. The Air EXT’s look like they will would limit the kickstarter, if you still have one of those, but they didn’t on our Suzuki RM-Z250 when we tried them on that machine. Perhaps if you were sloppy with foot placement, your boot heel could contact them and that would be annoying, but we didn’t have a problem. In whoop sections and while approaching jumps while standing up, you can even incorporate your heels to load the suspension to get increase height, similar to a seat-bounce. The bigger your feet, the more likely you are to feel the rear portion of the peg and that means in a positive way-absorbing abuse-and just being aware that it’s there. I wear a size 11, and I’d probably like the teardrop portion better with the teeth slightly dulled a little, but then again after about a couple hours on the pegs I was getting more used to them. I have never really feared landings, but I can appreciate what these pegs offer riders with Achilles and ankle injuries. Or maybe you’re learning how to ride on the balls of your feet, the Air EXT’s give the rider confidence when placing their feet back, when getting to the correct attack position. Ask Ryno how important riding on the balls of your feet are! #TwoChickens

While riding through deep ruts, these pegs can help allow large footed riders place their feet on the balls to keep their toes safe. I have had a couple of our bigger testers try the Air EXT’s and they comment they have less ankle/knee fatigue at the end of a long day of moto’ing. The Air EXT’s are like virtual floorboards for your dirt bike. The thing you have to remember when riding with these pegs is that the space to the rear brake pedal or shifter is greater. You will have to cover more ground and remember that when trying to make a shift or use the rear brake, when riding on the back of the Air EXT’s. 

I ended up going with the smallest cleat option on the pegs as those provided enough traction without feeling too tall on the bike. If you’re on the shorter side you could definitely benefit from the replaceable cleat height design and the difference it can make with your rider triangle. I didn’t however try the Universal Collar System (UCS) yet, which allows you to lower the footpegs from the stock position, but plan to with a couple test machines soon. 

At $255.95 for the Air EXT pegs and $19.99 for the fit kit, it’s not a cheap aftermarket footpeg purchase, but this is still a less expensive option than some other titanium offerings out on the market. Check these pegs out at Fastway.zone.com.

Specs:

•Weight: .85 pounds per set

•2024 billet aluminum

•Unique universal footpeg

•Precision engineered, manufactured, and assembled in the U.S.A.

•All footpegs ship with 2 sets of F3 threaded cleats– short 10mm, and tall 12mm cleats

•Requires Fastway Footpeg Fit Kit 

Vortex Ignition For 2020 YZ450F

The Yamaha YZ450F comes with the Yamaha Power Tuner App that allows you to change the parameters of the bLU cRU’s ECU settings. It allows the consumer to customize their YZ450F power delivery, so that they can enjoy a more friendly power character or a more aggressive type of delivery. While this system works very well for the average consumer what about the rest of us that may want to tune their YZ450F even further? What about having an ECU that has wider parameters and an ECU that can give you more horsepower, but make it rideable as well? Can we make our YZ450F even better with an aftermarket ECU? Is there a big enough difference in power delivery that it warrants spending an extra grand on an electrical part? I wanted to find these questions out, so I called upon Chad at XPR Motorsports to see if he could map a Vortex ignition for my 2020 YZ450F in order to see if it wold actually make it that much better. 

Unlike a KTM 450 SX-F it is very difficult to improve upon the Yamaha’s engine character. The YZ450F is the best production motocross machine made at this moment, so the gains are tougher to get through the aftermarket unlike the orange model. With a KTM I can slap on a Vortex ECU and immediately notice a huge difference in power as well as traction. However, I have been playing with the Vortex ECU on the Yamaha YZ450F for almost a year now and found out that it’s not that easy to make the Yamaha’s engine “better”. Chad at XPR Motorsports is one of only two people in Southern California that I would trust to help me with ECU testing (the other being Jamie at Twisted Development). I told Chad that I don’t necessarily want “more power” from the YZ450F, but I wanted more rear wheel traction with a broader, longer power (similar to a KTM 450 SX-F power spread). I can roll my corners really well on a KTM because it is so damn smooth off the bottom and I wanted to see if we could get some of that character on ol blue here.  

I am not going to sit here and tell you that getting a map that actually made me happy was easy because I think I gave Chad a headache more than once while doing this test. However once we honed in on what I was looking for, it was something that the stock Yamaha Power Tuner simply couldn’t do. With the help of XPR’s mapping and the desired power that I was looking for, I now had an easier to corner Yamaha YZ450F, with more traction out of area 3 (end of corner), as well as a broader/longer overall top end/over-rev. 

I wanted to keep the third gear lugability, but also make second gear more usable so I could make shifts later once exiting corners. This wasn't easy to achieve as Chad and I quickly found out. I got a longer second gear, but was losing some of that easy to ride third gear lugability because the engine was much freer feeling with the Vortex ECU. With a lighter engine feel you get less de-cel pitching, which is great because the chassis stays calmer, feels more exciting, has better recovery, but you also get less chugability when lugging your engine. Chad went went back to the drawing board and gave me another map that split the difference for me and made me really happy. I now had most of that third gear roll on lugging power, but still retained that free feeling engine feel that I loved when the track got rough. Having less engine braking on the YZ450F really helps this chassis stay calm when diving deep into corners with large bumps. 

I like that the Yamaha YZ450F is easier to start as well as fires up sooner with the Vortex on, so having this ECU on could really benefit a dead engine type of off road rider. With the XPR mapped Vortex, the mapping seems crisper/cleaner and never had a de-cel pop that I sometimes experienced with the TP 3.0 map. We mapped the Yamaha to a Pro Circuit exhaust and originally started with VP Pro 6 fuel, but that was simply too much power down low for me, so creating a map for VP T4/pump fuel made the Yamaha engine much more manageable in hard pack situations. 

The bad news about going to the Vortex ECU is that you lose all of your Power Tuner functions like the maintenance schedule, running time, etc. The Vortex comes with 10 pre-programmed maps as well as three fuel trim knobs that can help with your “Lo”, “Mid” and “High” rpm ranges. This is not an inexpensive mod, but it can help broaden the Yamaha’s power, make the hit more seamless down low as well as help the chassis when pushing the machine when the track gets rough. 

Is the stock ECU good? Yes! If you feel like the stock ECU/Power Tuner App has enough parameters and you’re happy, you DO NOT need an aftermarket ECU like this. 

Do I feel as though the Vortex ECU makes as big of a difference on the Yamaha like it does on the KTM 450 SX-F?  No, I don’t. The Vortex ECU on the Yamaha helps make it easier to ride, but Yamaha R&D did such a great job with their mapping that it may be hard for less picky riders really notice. KTM’s stock ECU mapping is not nearly as good off the show room floor, so the difference from going to a stock ECU to a Vortex on a KTM is noticeable by a wider range of riders.  

Who is this Vortex ECU for? This specific ECU on the Yamaha is for riders who love the stock engine character, but want a little more control off the bottom and more pulling power from second and third gears. Oh and how could I forget that this is not a cheap mod (at around a $1000.00), so you might have some coin saved up in your bank. 

Would I purchase this mod myself? Yes, but I am the type of guy who still likes to be competitive at the ripe old age of 42, likes to have a linear, longer power delivery and loves to tinker with stuff. If you’re like me this mod will make you smile. 

Conclusion: Overall I am happier with the Vortex ECU on the 2020 YZ450F because the bike has more controlled power and it makes it less work for me to ride harder. The downside is coming up with the 1K to purchase it! Guess I will be impatiently waiting on my stimulus.

Contact: Chad @ XPR Performance (951) 813 8873

Ride Engineering Full Performance Linkage (Husqvarna FC450)

Getting that comfortable feel as well as increased track toughness can be somewhat hard to find on the Husqvarna FC450. At least for me anyway. I can go to tracks that are soft and tighter and be completely happy with the Husqvarna and then go to a fast/choppy track that has more flowing corners and be confused on why this bike feels so different. I know a couple companies have been making different linkage ratios for the Husqvarna and KTM’s, but I wanted to try Ride Engineering’s performance linkage system on the FC450 to see if it actually improves upon the ride comfort on choppy tracks. 

 You might be saying to yourself, well what about the KTM Keefer? I do similar negative feelings on the KTM that I do on the white bike, but the Husqvarna does seem like it’s slightly more forgiving at times on rougher tracks. As you may already know this link also can work on the KTM, so if you’re on an orange bike, this test could also apply to you. I will be doing a full review on a couple different linkage systems (Ride Engineering/REP) on the KTM in the coming weeks, just to see if I can feel a difference between each. 

So what exactly am I looking for here? Why is there a need for a different linkage ratio on this machine? Why didn't the R&D team at KTM/Husqvarna choose the ratio that Ride Engineering came up with in the first place? I will give you some insider knowledge on the R&D process a little before we dive into this test. Sometimes when OEM R&D teams test suspension, often there is a few linkages that the test riders have to weed through to see which one works best for a wide range of riders on said bike. Setting up a bike for the masses is not easy to do and most of the time the OEM’s choose a setting that is more of a “comfort setting” than a performance setting to offset the stiffness of the chassis. Comfort is needed on any new production motocross bike and getting a suspension spec that coincides with the correct linkage ratio as well as frame stiffness can be tricky. Not every bike benefits from an aftermarket linkage ratio, so don’t think you need a linkage on every bike on the dealer floor. If you’re happy with the feeling that you get when you ride your machine then try not to overthink it. JUST GO RIDE! If you feel what we are describing in this test then possibly a linkage could benefit you. If you DO NOT feel the things we are explaining in this test, you can simply disregard it and move on to something else you want to add to your FC450.   

What I Want Out Of The Rear Of The Husqvarna 2020 FC450?

The rear of the Husqvarna FC450 feels somewhat rigid on acceleration chop and I can feel like my rear end is dancing around when hard on the throttle out of rough corners. I spent some days searching for some added traction/comfort by changing sag settings, spring rates and clickers, but came up empty handed. I also tried a WP Pro Component shock and that just exacerbated my problem a little more on acceleration, creating a firmer feel out of corners. Even though I had more hold up and less fade with the Pro Component shock, I wasn't happy with my acceleration feel. 

What Did I Get Out Of The Ride Engineering Performance Linkage? 

Ride Engineering recommends that you go up a spring rate with their linkage, but I wanted to try it with the stock 45 N/m spring rate as well as a 48 N/m. The Ride Engineering pull rods are 1.3mm longer than the stock rods and the knuckle is more progressive, so it ramps up different than the stock knuckle. Once installed and the sag was set to 104mm, I immediately felt slightly more comfort out of the rear of the bike on acceleration, but also noticed it being a little low for my liking in that area. On steeper jump faces or flat landings I felt like the shock bottomed and felt empty on high speed compression. After increasing the high speed compression, it helped a little on jump faces as well as helped the empty feel on slap down landings, but it hurt acceleration traction. I installed the heavier 48 N/m spring on, reset my sag, jumped back out on the track and was quickly greeted with a firmer feel, but the firm feel didn't translate into a harsher rear end like the stock linkage/spring had. 

The rear of the Husqvarna stayed up in the stroke more out of corners, but also had a freer feeling to it, which increased my rear end traction. Another positive to the heavier rear spring/Ride Engineering linkage combo was that the control of the Husqvarna was better when hitting de-cel bumps at speed. At times with the stock shock/link, the Husqvarna would ride too low and have a sudden kick to the rear end that left me with a sensation of less control leading into corners. With the heavier rear spring and Ride link the initial braking bump feel was firmer, yet the FC450 moved less when getting to the fifth, sixth, and seventh braking bump into corners. I could hold on the throttle a little longer because I had more control as well as better action of the rear end. If there was a negative to the heavier spring/Ride Engineering link, I would have to say that it can make the Husqvarna a slightly slower cornering bike on initial lean, but to me I didn't mind the slight slower turn in feel. I know some of you may not like that, but if you find that this is bothering you then simply run your sag at 103mm and this can help initial turn in. 

Like I mentioned above, I tried the WP Pro Component shock with the Ride Link set up and it gave me a similar feeling that the stock shock/Ride link set up did, but with even more hold up when ridden aggressively (of course that has something to do with the valving as well). I liked that with the Ride Engineering knuckle/rod set up of the FC450 felt less firm on acceleration and yet still had more control on de-cel bumps. 

This Ride Engineering Performance Link is $449.90 and is available over at ride-engineering.com and fits current Husqvarna/KTM models. 

If you’re a KTM owner and looking for a little comparison, stay tuned for a REP/Ride Engineering Performance Link comparison as both companies make a different knuckle ratio for the white and orange machines. Will I be able to feel the difference? Find out soon! 

2020 Honda CRF450R Three Way Muffler System Comparison

The 2020 Honda CRF450R is a popular machine. After all of my years with Dirt Rider Magazine as well as doing my own thing over here at Keefer Inc. Testing there has been one thing that hasn't changed… The amount of page views and questions that I get about the Honda are always more than any other color! As a test rider, I like the Honda CRF450R because it’s one of the most difficult bikes to set up for a wide variety of tracks, so that keeps me trying different products and thinking of ways to try and make it better. As a consumer or a local racer, the 2020 Honda CRF450R can drive you nuts at times right? It’s super fun to ride, but sometimes can be a handful at certain types of tracks.

In this article I am going to test the Yoshimura RS-9T, FMF 4.1 RCT, Akrapovic Evolution titanium muffler systems for the 2020 Honda CRF450R and give you some feedback on each one’s engine delivery character. I picked these three muffler systems because they have been one of the best three that I have tried on this particular machine. This isn't a shootout as much as what each system can bring to the table. These three muffler systems have similar characters in some areas of the powerband, but also have enough differences in which you can make a decision based on what type of power you want from your Honda.

Fun Fact: I tested these mufflers on the 2020 Honda CRF450R as well as the 2020 Honda CRF450RWE just to see if the ported head, that the RWE comes with, would change the way each muffler delivered its power. After going back and forth on each machine, the character of each muffler system was the same on the stock cylinder head as it was on the hand ported Works Edition head. The description/results below is accurate for both machines.

FMF 4.1 RCT Muffler System:

The FMF 4.1 muffler system has more bottom end and throttle response than the other two muffler systems in this class. The Honda doesn't necessarily need more bottom end, but the way the FMF system delivers its power can give the rider some added freedom when trying to ride third gear through corners. The bottom end comes on strong and the Honda keeps its exciting, crisp RPM response feeling, but lets you run third gear through corners more than the stock, Yoshimura and Akrapovic muffler systems can. Using second with the FMF system almost makes the Honda a little too much too handle (on roll on) through very tight corners. When going to the FMF 4.1 system I reverted back to map 2 (mellow map) instead of map 1 (standard map) and ran 14/52 gearing. By using map one and going to this gearing ratio, it helped calm the Honda’s chassis down in second gear a little, but still kept its fun natured, snappy engine character. Mid range is broader and pulls farther than the stock muffler, but isn't as good as the Yoshimura system in this area. Up on top end the FMF system almost mimics the Yosh in pulling power feeling on the track with maybe slightly less over-rev than the Yosh system. What I like about the FMF muffler system is that it allows the rider to ride a gear higher in some areas of the track and rewards riders that like to lug their bikes more. The Honda in stock form is not the best lugging machine, but with the FMF system it gives the red bike more of a lazy man’s type of feel by allowing me to use third gear more. The FMF system is louder than the Yoshimura or Akrapovic systems by quite a bit even with the inserts in, but keeps that racey deeper sound. 

The good news is that the muffler packing has lasted longer than I expected. We are over the 12 hour mark on the 4.1’s and they still sound good. I used to get only 8-10 hours on other single FMF muffler systems, but these duals have proved to be more durable. 

Yoshimura RS-9 Muffler System With Works Edition Headpipe: 

Once installed and on the track the Honda’s exhaust note turned from high pitch 250F’esq to a deep throaty more traditional 450 factory race bike sound. The crack of the throttle (or RPM response) is slightly smoother and less crisp than the stock or FMF systems, but to me this is a good thing for the Honda chassis. Rolling out of corners, while in second gear, the Honda feels like it has more traction than the FMF and was more controllable while accelerating out of hard pack corners. The slightly smoother RPM response takes away the Honda’s excitement feel ever so slightly, but helps you gain a little more control coming out of corners. The mid range pull is healthier than stock, but with the Yoshimura system you will not be able to pull third gear through tight corners as well as you can with the FMF system. The Yoshimura system is very controlled and has more mid range torque than any other muffler in this test. Even though the Yoshimura system doesn't have that bottom end throttle response like the FMF system the recovery is still very good. With just the flick of the clutch lever (in third gear) the Honda will be in the meat of the power once again and you will be down the straight in a hurry. I noticed top end and over-rev was as good as stock (which is great), but not as good as the Akrapovic. To me the Yoshimura system is like the YZ450F of the muffler world. It does everything “pretty well” and gives you more rear wheel consistency that the Honda needs. You could tell Yoshimura was focused on smoothing out the bottom to mid-range pulling power when they designed this muffler system and they succeeded in doing so. It is also impressive that they didn’t lose any top end/over-rev in the process and gain a little more control.

The muffler packing that the Yoshimura RS-9 mufflers come with is superb and will last you longer than any other packing in this group. Yoshimura also offers the customer refurbishing, just in case you don’t want to DIY. The stickers on the mufflers themselves also last longer and will not turn color as fast as the others in this group.  

Akrapovic Evolution Muffler System:

Once I swapped to the Akrapovic Evolution muffler system, I could immediately tell this system helped the Honda chassis calm down the most. The Evolution system lets the Honda’s engine roll on smoother at low RPM’s and that smoother feel helps the rear wheel connection as well as provides less pitching (off throttle) than any other system in this test. AKA MORE COMFORT!!! The Honda CRF450R now builds a smoother roll delivery and a pulling power that is longer through the mid range than the FMF or Yoshimura. This type of character can allow you to use second gear in corners more because that second gear hit is not as abrupt or quick, so that doesn't upset your technique or the chassis. The Akrapovic also allows the rider to shift later out of corners and that means second gear is more usable with its increased over-rev capabilities . Pulling power up top is increased slightly as your shifting points can be altered now because of the longer pull in each gear. I ran the 14/52 gearing with this muffler system but decided on going back to the stock 13/49 gearing in order t get some mid range recovery back. The Akrapovic doesn't have the the bottom or mid range throttle response like the FMF or Yoshimura systems so this can give the Honda a slightly heavier feel on tighter tracks. The Honda has so much power to work with that a little less “hit” as well as “recovery” can actually help on faster/flowier tracks, but can also make it slightly heavier feeling than the other two mufflers when moving the Honda side to side. I really like that the Akrapovic system relaxes the engine as well off throttle and provides the CRF450R with less engine braking. This really comes into play on tracks with hard pack chop and small de-cel bumps.

The sound/pitch of the Akrapovic is ridiculously quiet when on the track and will almost give you that MXGP sound and feel. It still has that racey, crisp sound on higher rpm’s, but just not that raspy high pitch tone of the stock muffler. I preferred the quiet inserts left in because it created more back pressure and gave me more traction at the rear wheel (out of corners) in all three engine modes. I was normally a map two guy with the stock muffler, but with the Akrapovic installed I am now a map one guy all day long because of the added rear wheel/friendlier connection. The muffler packing has proved to be durable but the stickers on the mufflers turn color quickly and get blown off.

Overall: I always let people know if you have no problems with your stock muffler system and like the way your Honda runs then by all accounts you can disregard this test. Just because I test something here doesn’t mean you absolutely 100% NEED it! If you’re in the market for a muffler system, have some extra money and want to know which direction to go then study up! If you want to alter or change your Honda’s engine character slightly, this test can help you decide on which direction you want to go. To me all of these systems in this test are better than the stock system because it helps the Honda’s chassis in one way or the other and offer spark arrestor inserts for the off-road guy. The Honda doesn't need more power as much as it needs a broader more forgiving connection to the rear wheel. These systems help the Honda in this area. 

Breaking The Systems Down:

Bottom End: FMF

Mid Range: Yoshimura 

Top End: Akrapovic

Over-Rev: Akrapovic

Low RPM Response: FMF

Mid RPM Response: FMF

Top RPM Response: Yoshimura

Controllability/Connection: Akrapovic

Weight: 

FMF: 8.5 lbs.

Yoshimura: 8.4 lbs.

Akrapovic: 8.4 lbs.

Sound/DB:

FMF: 121.1 DB

Yoshimura: 116.8 DB

Akrapovic: 116.1 DB

Pricing: 

FMF: $1499.99 www.fmfracing.com 

Yoshimura: $1499.99 www.yoshimura-rd.com 

Akrapovic: $1549.99 www.akrapovic.com 

If you have any questions about this test, please feel free to email me at kris@keeferinctesting.com. I am here to help if needed!

RIDE ENGINEERING 2018-2020 Suzuki RM-Z 450 Performance Link

By Dallas Dunn:

I’ve been helping out Keefer with photography content for some time now, but I’ve been wanting to get more into the testing side of things so Kris has gave me the opportunity to ride the 2020 Suzuki RM-Z450 test bike for the year, so the first mod for this bike was going to be the Ride Engineering 1mm longer lowering link. I wanted to give you a normal everyday blue collar perspective. I am by no means a professional test rider, in fact I am a heavy equipment operator that likes to ride his dirt bike. So if you can relate to that and have a RM-Z450, maybe you can relate to this test as well.

Simply installing the Ride Engineering link helped balance the RM-Z out on de-cel. If you’re running the stock suspension (valving/springs) this simple mod will help the RM-Z from wanting to transfer its weight towards the front end. The RM-Z450’s BFRC shock is known for unloading on de-cel (or riding high off throttle) and that can cause oversteer (knifing) on entrances of corners. Once you install the longer Ride Engineering link arms on the Suzuki it will settle down on de-cel and not pitch towards the front end as much. I noticed right away the bike felt more predictable and compliant coming into choppy braking bumps while keeping the rear end planted with less diving on de-cel. It gave me more sense of predictability and control when entering corners compared to the stock setup. Having comfort and predictability are things I look for when trying to improve my speed and technique. Running the sag at 107mm (fork height 4-5mm) with the link arm will alleviate some of your balance issues on the #RMaRMy. 

This Ride Engineering link Retails for $219.99 at www.ride-engineering.com.

You can use the code Keefer-20 to save some dough as well.

FMF 4.1 Full System Vs. Akrapovic Evolution Full System Vs. Akrapovic Slip On

We recently received the 2020.5 KTM 450 SX-F Factory Edition and after dissecting it for a few weeks, we thought we would test a couple different muffler systems on it. We wanted to see if we could improve upon the KTM Factory Edition’s delivery. The KTM comes with an Akrapovic slip on we thought since we have never tried one of their full systems, we would give that a go as well as an FMF 4.1 RCT full system to see how each compares to the standard Factory Edition set up. Just in case you were wondering, we also compared each muffler to one other and give you a breakdown of each category below. 

FMF 4.1 RCT Full System ($1049.00):

With the FMF system installed you will not be getting increased bottom end pull on the KTM, but you will be getting a little more bottom and mid-range RPM response (or throttle crack for you newbies). I noticed the added RPM response more out of corners (versus the Akrapovic) and the FMF system makes the KTM engine character slightly more free-feeling and exciting. I also appreciate that I am not getting any added de-cel popping (or lean sensation) with the FMF system. The KTM ran just as clean with the FMF system on then it did with the stock muffler. Where you will notice the most improvement with the FMF system is through the mid-range. The mid-range “meat” you will get out of the FMF 4.1 system is downright impressive. Rolling the throttle on out of corners and accelerating you will notice an increased pulling power that wasn't there with the stock muffler. 

Whether you're coming out of a corner in second or third gear, you will notice some extra torque feel getting to the next obstacle. With the added mid-range meat of the FMF system it really helped some of the gearing issues I had on tighter, less flowy tracks I tested at. Gaining some mid-range let me use third gear in some corners that I wasn’t able to with the stock system. With the stock system I would roll into these corners in second gear and have the right amount of "pop" to get me out quick, but I had to shift early once exited, to keep the rear wheel from spinning. Third gear was too tall of a gear to get me out of the corner quick, but provided less wheel spin on the exit. It was always a struggle for me to decide on which gear to use when being pressured from behind, by another rider. 

With the FMF installed I could easily use third gear and have enough "pop" to get me out of the corner in a hurry, yet it kept the wheel spin to a minimum by being able to use a taller gear. The FMF’s 4.1 system made me think less and twist the throttle harder, something I like doing. I didn't get any more top-end with the FMF installed, yet it didn't take any away from the orange machine. I did notice slightly less over-rev with the FMF system (from stock) when I got lazy.

Akrapovic Evolution Full Muffler System ($1299.99):

The Akrapovic Evolution full muffler system has a similar character to the slip on version that comes with the Factory Edition, but with added bottom end roll on and mid range. If you’re expecting a ton of added RPM response (excitement) from your full system compared to your standard slip on, you will be disappointed. You simply will not be getting that much added rpm response with the Akrapovic full system. Instead of a smooth roll on that the FE comes with it now has a little more pulling power in second and third gears and pulls those gears much longer.

Mid range pulling power is increased and the muffler pitch is so quiet you never really feel like you’re “on the gas”. The mid range pull is much more linear and longer than the standard slip on and being able to shift a little earlier with the full system makes it easier to ride in softer conditions. I had a hard time with the KTM 450 SX-F Factory Edition at softer tracks not recovering, if I shifted early out of a corner. With the full system at the same track I was able to shift into third and not have to worry about covering the clutch as much. 

Top end and over-rev is where this Akrapovic Evolution system shines. Adding top end and over-rev to the already very capable Factory Edition only makes this machine more fun to ride. Again, I can’t stress on how deceiving this system is because of it’s quiet nature. I really had to focus in and feel how quick I was going from point A to point B on the track because the pitch of the muffler never sounds “racey”. However even with its quiet note, the Akrapovic full system lets the KTM pull so much farther that it almost feels like a swapped to an aftermarket ignition. The connection to the rear wheel with the full system is unmatched and even though it may seem like it’s not very responsive, the KTM with the Akrapovic full system allows the rider to get on the gas sooner through corners.

If you’re reading this and wondering why you can’t simply purchase an Akrapovic headpipe for your Akrapovic slip on, the answer is they will not mate up. The Akrapovic slip on has a smaller diameter OD, (where it meets the stock headpipe), so purchasing just the headpipe will not work.

Akrapovic Vs. FMF:

Below are your typical engine categories and which muffler is best in what area. 

Bottom End: FMF

Mid-Range: FMF

Top End: Akrapovic

Over-Rev: Akrapovic 

RPM Response: FMF

Rear Wheel Connection: Akrapovic

Weight: (Akrapovic 6.2 lbs.) (FMF 6.9 lbs.) (Standard FE 8.1 lbs.)

Which One Should You Purchase?

If you’re looking for more bottom end excitement or rpm response look towards the FMF system. If you’re looking for the lightest muffler available and want more top end/over-rev you will love the Akrapovic. Cost is also a factor to me, so if I am looking at the most bang for my buck, the FMF is less money and I’m getting a good performance gain compared to the standard Akrapovic slip on that comes on the FE. The FMF muffler stands up to more abuse as the Akrapovic can look hammered quicker. That being said I was super impressed with the connection that the Akrapovic had on dry/slick tracks, so depending on what conditions you ride could be a factor in your purchasing decision as well.

Pro Circuit Link Arm (2020 Yamaha YZ450F)

I have tried links in the past on previous generation YZ450F’s with less than stellar results, but since Yamaha changed the frame on the 2020 machine, I thought I would revisit a link to see if it helps improves the Yamaha’s feel around the track. 

Pro Circuit's linkage arms are CNC-machined from billet aluminum and are designed to stiffen up the initial linkage curve in order to try and improve the geometry of the YZ450F’s chassis, in order to try and make the bike more stable in certain areas of the track. The linkage arms includes all of the required bearings and seals and is ready to bolt up. I wanted to see how it worked with the stock YZ450F suspension valving, so since Pro Circuit is backordered on them for a while, I purchased the Pro Circuit linkage arm at rockymountainatvmc.com for $189.95 . Once I received the PC link, I went to a few tracks to try the it and the stock link, back to back , to see if the Pro Circuit link is a benefit to the average rider. 

One thing that I want from the stock 2020 Yamaha YZ450F is less movement from the rear end under acceleration. With the stock link, the rear end can squat  too much at times (under throttle) and give me the feeling of less connection to the rear wheel under load. I do think the new 2020 frame and suspension valving has helped de-cel pitching, but once the fork is broke in, it can dive a little too much under hard braking. 

After I installed the PC link I re-checked my sag numbers to make sure they were in the spec I desired. I ran 105mm of sag with the stock link and am currently at 105mm of sag with the PC link. With the PC 143.5mm link installed (142.0mm is stock) the Yamaha has a noticeably different feel to it on the track. I immediately noticed that my rear end felt firmer under acceleration, but that feeling wasn't such a positive change. I went back to the van and turned my high speed compression (on the shock) out a quarter turn to help soften up the feeling on acceleration chop. Once I adjusted the high speed compression, I could start to feel the benefits of the Pro Circuit pull rods. 

Off throttle (de-cel) the Yamaha YZ450F felt flatter and less front end heavy, which gave me a YZ450F that now had more control on braking bumps. Corner entry wasn't improved, but I could feel how the Yamaha could lean over better through the middle to end of each corner. With the Pro Circuit link It took slightly less effort for me to continue my lean on the Yamaha, which usually isn't its strong point. Out of the corner (with the softer high speed compression setting) the Yamaha had more rear wheel traction and followed the ground better on acceleration bumps. The rear of the bike was higher in its stroke with the PC rods and gave me more of a plush feel than the stock link. I am able to run a softer high speed compression setting as well as low speed to get more comfort on choppy ruts. 

The overall feeling of the YZ450F with the PC link is a slightly calmer chassis off throttle with a better mid to exit cornering feel. If I had to point out a negative about the PC link it would have to be that once you’re off throttle the Yamaha has a firmer rear end feel. Even though I am gaining control on braking bumps, the YZ450F will feel firmer if the rider isn’t aggressive or pushing the bike. I feel the Pro Circuit linkage arms reward a more aggressive rider, so if you’re the average weekend warrior that likes to cruise his Yamaha YZ450F and is comfortable with your set up, these Pro Circuit linkage arms may not be the best purchasing decision. However, if you’re looking for more control on braking bumps, with a firmer feel and an easier area 2 to 3 (see testing term explanation below)  through corners, then the Pro Circuit linkage arms make a positive difference. 

Cornering Testing Terminology: 

Area 1: Beginning of corner (initial lean, tip in)

Area 2: Middle of corner (weight feel, traction, cornering stability)

Area 3: Exit of corner (rear wheel traction/connection, comfort)

Husqvarna FC450 Triple Clamp Offset Test

The Husqvarna FC 450 Rockstar Edition comes standard with the Husqvarna Technical Accessories Adjustable Factory Triple Clamp. If you’re riding a standard FC450 these clamps adjustable clamps are available through your local Husqvarna dealer for $599.99. The adjustable clamp comes standard at a 22mm offset but can also be moved to a 20mm offset as well. The factory Rockstar Energy Husqvarna team is currently running these on their bikes and to me these factory clamps have a softer feel to them compared to the triple clamps that come on the standard 2020 FC450. There is less rigidity as well as more flex with the Husqvarna adjustable factory or X-Trig clamps compared to the standard/stock FC450 clamps. I have never really messed with the offset on the Husqvarna for motocross, so I thought I would experiment with each offset and even throw in an X-Trig 24mm offset for good measure. Below are some of the positives and negatives of each offset, as well which type of track each offset would benefit you the most.

Criteria: I chose Glen Helen as my testing grounds. They have the national track, which is fast and very rough as well as the REM track, which has more turns and is slower speed. I gave each offset setting a try on both tracks to see what I would lean towards in hopes to give you a direction for your personal needs.  

Offset: The triple clamp-offset is the distance of the horizontal center line of both fork tubes to the center of the steering axis, about which the fork legs are offset from the steering axis (referred to as dimensionX). The offset set can be seen at a glance by the marking on the triple clamp.

20mm Offset Husqvarna Clamp: 

+ Lean in is made easier on initial turn in

+ Front tire contact patch is improved on de-cel

+Lightweight feel improved (side to side movement)

- On throttle front end hunt/peck (deflection more apparent)

- Slight oversteer on long sweeping corners 

- Slight less comfort on initial bump impact 

Who is this setting best for? 

20mm offset is best for slower riders who have trouble with cornering or leaning into a rut. This setting makes it easier for the FC450 to fall into a rut and stay there. This setting was also much better for the tighter/slower track as there was less on throttle stability issues at the tighter track. 

Who is this setting not for? 

20mm offset is not for faster riders who want stability out of their machines on faster tracks. There is a lot of movement in the front end, on throttle, which leads to deflection in square edge. 

Best Overall Fork Setting With 20mm Offset:

Height: 1st line

Air Pressure: 11.0 bar

Comp: 11 out

Rebound: 16 out

22mm Offset Husqvarna Clamp:

+ Stability improved over 20mm offset (on/off throttle)

+ Bump absorption has more comfort than 20mm offset

+ Cornering stability is improved 

- Slightly heavier feel than 20mm (side to side/lean in)

- On throttle rear end squatting more (feels low)

Who is this setting best for?

For me this is the best all around setting for flowy/faster/intermediate terrain motocross tracks with bigger bumps. It’s a blend of good stability and predictability. I can hit bumps harder with the 22mm offset without the chassis reacting too fast. 

Who is this setting not for? 

This setting is not for fast west coast GP style courses or the older vet rider that needs assistance with cornering. Sliding the fork up to the second line helps this, but if you’re having trouble sticking in a rut, the 20mm offset can be more helpful than the 22mm setting. 

Best Overall Fork Setting With 22mm Offset:

Height: 1st line

Air Pressure: 11.1 bar

Comp: 14 out

Rebound: 15 out

24mm Offset X-Trig Clamp:

+ Very planted feeling chassis down choppy hills

+ Bump Absorption feel is better than 20/22mm offsets

+ Sweeping cornering stability/comfort/contact patch better than 20/22

+ Less vibration through bars with PDHS mounts

- Side to side movement feels lazy/heavy (initial lean)

- Vague front end feel while leaning in ruts (going up on fork height helps this)

- Bar pad doesn't fit because of PDHS mounts

Who is this setting best for?

The 24mm offset would be beneficial to any rider who wants more high speed front end stability. The 24mm offset helps with bump absorption on throttle and keep front tire straight. West coast GP or off-road riders would benefit from a 24mm offset.  

Who is this setting not for:

The 24mm wouldn't benefit most moto riders that are looking for a quick handling machine with a blend of straight line stability. The 24mm is more of a point and shoot type of offset. Come in straight and pivot/rear wheel steer out. 

Best Overall Fork Setting With 24mm Offset:

Height: 2nd line

Air Pressure: 11.0 bar

Comp: 10 out

Rebound: 14 out

Sunstar Works Triplestar Sprocket

Sunstar is the largest OEM supplier of motorcycle and all terrain vehicle (ATV) sprockets and brake discs in the world. In fact, if you’re on a Japanese machine most likely it came from the factory with Sunstar. Sunstar offers the Works Triplestar combination that is lightweight, looks good, and from what I found out recently, is pretty damn durable for an aluminum sprocket. Since Sunstar sprockets came stock on our YZ450F and I’ve had great luck with them, I thought why not try out their Triplestar sprockets, to see how long they last.

The one problem about aluminum sprockets is they simply don’t last long right? I have tested Renthal aluminum sprockets in the past that have broke teeth within 4 engine hours. That’s not acceptable! I am also a firm believer of when your sprockets get worn out and its time to change them, it’s also time for a fresh chain, so make sure to try and always change the whole drivetrain at the same time. This test isn't a big elaborate techy kind of test, but more of a testimonial of what I thought of the Sunstar sprockets. It’s not easy to talk about a sprocket, so let me just tell you how long it lasted and give you some other food for thought. 

I am lucky to get ten engine hours on an aluminum sprocket out here on the west coast so changing out my drivetrain every couple weeks is the norm. Yes, I can ride up to ten engine hours every 7-10 days. Shockingly, I have just over 16 engine hours on this Sunstar Triplestar sprocket and it looks like this (see above). Not bad right? The Sunstar quality has been superb and when I told the guys over at Sunstar that I was shocked on how good the sprockets were, they acted surprised that I was so shocked. I know Sunstar comes on a lot of production machines, but in the racing world they’re not as prevalent in my mind for whatever reason. I kept the standard 13/49 gearing on the YZ450F and haven't had an issue with the Sunstar Triplestar sprockets breaking teeth yet. I am very impressed on the quality and durability of the brand. 

 Now I know most of you are asking yourself “why doesn't he use steel sprockets or at least a Twinring”? I like to keep aluminum on my test bikes because every time I’ve had a chain failure, it has been with a steel rear sprocket. Rear steels are hard on chains, especially if you’re a moto guy, so for my peace of mind, I stick with aluminum. I have ran steel sprockets in the past and although they last a long time, I have snapped more chains running steel sprockets than aluminum, so I choose to stick with the lighter rear sprocket. Mix matching a steel countershaft sprocket with an aluminum rear is not uncommon for me and when doing that steel/aluminum combo, I have experienced zero chain failures. If I was running an o-ring chain on my test bikes, I can run steel rear sprockets with better results. If you’re a off-road guy that rides a ton of mud, this sprocket test may have nothing to do with you. Steel sprockets, o-ring chains, and GNCC type racing is the norm, but for moto what I described above is what I felt.

If you’re looking for an aluminum rear sprocket that has a great lifespan look no further than this Sunstar Triplestar.  

Ride Engineering Performance Link (KTM 125SX)

My son loves riding his 2020 KTM 125SX, but comments all the time on how he feels like the KTM sits taller than his Yamaha YZ125. When I watch him ride I notice that the rear end of his 125SX kicks him in his ass when hitting braking bumps and when that happens, it makes the front end dive too much on corner entry. He only weighs in at around 115 pounds, so going down a spring rate on the shock was a must, but to me, the bike still looked unbalanced on de-cel.

I called up Adrian at Ride Engineering and asked what he had for the KTM 125SX and we both agreed to try a rear link to see if that would help balance out the bike. This Ride Engineering link lowers the back of the KTM 125SX chassis by 7mm to try and improve the ride balance. I set the sag at 103mm with the Ride Engineering link versus the usual 105mm of sag that we were running on Aden’s KTM. Just know that you might have to adjust your air pressure setting on your AER fork to get the right front end feel, since you’re dropping the rear of the bike with the new link (more on that below).

For this test I had two KTM 125SX machines. One was set up for my son, with his softer shock spring and one was just a bone stock KTM 125SX with the sag set for me at 105mm. We started later in the day at a couple tracks on separate days to make sure the track was nice and broke in before we started to make our changes. Doing this ensures that the track doesn't change too much from each change we made to the orange machines. With the Ride Engineering link I noticed better tracking/acceleration coming out of choppy corners and slightly more stability off-throttle. I really liked that the link helped the ride attitude of the KTM when leaning, under throttle, on choppy terrain. I had more trust in the KTM when loading the chassis hard on throttle. I didn't get near as much kicking coming down rough hills and the overall cornering character didn’t suffer. I was worried that this Ride Engineering link would hurt turn in, but to my surprise it didn't affect the KTM’s easy natured turn in character. 

Aden’s comments didn't exactly mimic mine, but one comment that actually made sense was he did like that he felt lower to the ground, when sitting, and that helped him with his starts. When watching him ride the bike was visibly less busy in the rear and didn't give him as much kicking on de-cel. The length of the Ride Engineering pull rods are 1.3mm’s longer than stock and come in at a 149.5mm overall length. Aden doesn't know enough about chassis testing to give me some great feedback, but some of his comments overlapped mine. I more or less watch the bike when he rides and then decide if it’s a good direction or not. We decided to leave the Ride Engineering link on his bike after we both came to an agreement that he looked/felt better on a rough track with it on.

If you do decide to get the Ride Engineering Performance Link just know that you may have to adjust your AER fork pressure, if you’re still on air forks. Now with the Ride Engineering pull rods installed the rear end will ride a little lower, so the front end might seem a little high. Dropping the air pressure anywhere between .2-.5 bar might be needed to get some added front end traction. We dropped Aden’s air pressure from 8.3 bar to 8.1 bar at some tracks and even down to 8 bar at others. Try running your normal AER pressure when you first put on the Ride pull rods and see how your front end feels though corners. If you feel like your front end is tall, your front end is pushing, or have a vague front end feel, just try to drop your air pressure slightly. This will help let the fork use more of its stroke and get that front tire to bite into the ground more. 

The Ride Engineering Performance Link comes complete with bearings and seals and is not that difficult to install. I literally changed the link out at the track on several days. If you’re looking to get a little more stability and rear wheel traction without sacrificing cornering, then you might want to try this link. MSRP is $219.95, but you can use the code Keefer-20 to save 20% if you want to order through ride-engineering.com. 

Yamaha YZ125 Pipe/Silencer Comparison (Pro Circuit Vs. FMF)

For over 10 years the YZ125 engine has remained the same. At one time it was the best 125cc engine around, but in recent years that award has gone to KTM/Husqvarna. KTM and Husqvarna’s latest 125cc engines have a wider powerband and is simply more exciting everywhere on the track. Compared to the KTM and Husqvarna the YZ125 lacks bottom to midrange. The rider has to fan the clutch more to remain in the meat of the power curve, which can make a rider more tired in race conditions. I know it’s a 125, but compared to the other two models, it’s just more work. However, once I put my 14 year old son on the YZ125 he mysteriously had faster lap times compared to his KTM 125 SX. How can this be? The reason is “I think” he can corner better because of the KYB suspension and the fact that the YZ125 isn't that “barky” off the bottom end helps him carry more speed. At least this is my theory. This is his first year on 125’s and he doesn't need a rocket ship quite yet because his arms look like spaghetti strings and his legs remind me of a long bird. There’s just not a lot there yet! He’s all D&R! 

To allow him to compete with the other kids his age on the other two colors, he does need a little bit more down low, in order to get out of the gate better. One of the best performance upgrades you can buy for a YZ125 is a good-performing aftermarket pipe/silencer. Exhaust pipes are relatively inexpensive and they do not directly affect the durability of the machine. I tested the FMF Factory Fatty Pipe/Shorty silencer as well as the Pro Circuit Works Pipe/R-304 Silencer combos to see how they compared to one another. I then let Aden chime in on what he feels was better for him. Editors Note: (Aden’s opinion was given to me before this article was written)

FMF Factory Fatty/Shorty Silencer (Kris’s Breakdown): The FMF pipe/silencer combo adds a little more pulling power out of corners over stock, while the mid range on the FMF pulls slightly longer than stock and climbs farther through the top end. The FMF set up doesn't provide more over-rev over stock, but you will notice a healthier second and third gear pull down the straights. The YZ125 runs much cleaner with the FMF pipe/silencer (compared to stock) and looks stealthy as the silencer is hidden behind the number plate. I like that the FMF pipe comes with o-rings already installed and is ready to put on. The faster the track, the more this combination shined.  

Pro Circuit Works Pipe/R-304 Silencer (Kris’s Breakdown): The Pro Circuit Works Pipe and R-304 silencer has a deeper sound than the FMF/stock system and gives the YZ125 more bottom end than the FMF. The PC pipe/silencer has increased pulling power out of corners (mid-range) and just feels like it’s more torquey. When rolling the throttle on you’re able just to feel more meat as you’re able to shift the YZ125 a little sooner. The top end signs off a little earlier than the FMF, but the Pro Circuit allows the rider to have more freedom with his/her riding without having to cover the clutch as much. 

Aden’s Opinion: “In my opinion I think that the the Pro Circuit pipe works better for me because it’s more aggressive coming out of corners than the FMF pipe. Do not get me wrong, the FMF pipe is a really good pipe & silencer, but I like the Pro circuit pipe, because it fits my riding style better. For example, my dad tells me I’m more of a 4 stroke kinda guy, I guess because I lug the bike a lot and the Pro circuit pipe has more bottom end, when I fan the clutch coming out of corners. In my dad’s world he calls that “recovery time”, I know this because I hear him say it all the time on the phone. The FMF pipe & silencer takes a little longer for the aggressiveness to hit when I am coming out of corners. Both pipes are better than the ugly looking stock stuff, but to me I prefer the Pro Circuit by a nose”. -Aden Keefer 

Conclusion: Both companies provide a better product than stock. I did raise the needle clip up to the second position (from third) before we started testing and that proved to be the best overall jetting from sea level to 3500ft. We think both companies have a purpose and have areas where their the strongest. If you are riding GP’s or faster type of tracks the FMF system works well because it allows the YZ125 to pull longer on top end. If you are riding tighter tracks or have a child coming off of an 85, the Pro Circuit system could help give him/her more recovery time when they make mistakes (and they will make mistakes).

If you have any questions about this test, feel free to email me at kris@keeferinctesting.com.

FMF 4.1 RCT Stainless Muffler System For 2020 YZ250F

Written/Tested By: Michael Allen

It’s no secret that the YZ250F is one of, if not the best 250F in the class for 2020. One of the things that makes the YZ stand out is the raw amount of torque it produces compared to the other bikes in the class. Some of the other bikes may put out comparable peak horsepower numbers, but when it comes to useable bottom end torque no one comes close. After the 20-hour mark we started to really notice the stock exhaust getting a raspy, hollow sound that was getting on our nerves, so we called FMF and ordered up their Factory 4.1 RCT Stainless full system with carbon end-cap. The 4.1 stainless system has a great look with the carbon cap and has a weight savings of just north of one pound over the stock system. We went with a stainless system for the durability of stainless over titanium. Stainless slip fit joints last longer than titanium and therefore will not get as loose over time.

Installing the system was very straight forward and easy, as well as fit and finish being top notch. Something I really like about the FMF system is that you are still able to use the stock muffler heat shield on the left side of the bike. I can’t tell you how many Yamaha’s I have melted pants on when the left side of the bike doesn’t have a heat shield. Unlike the stock systems raspy sound, the FMF has a deeper tone that is throatier and far less annoying. Another plus of the 4.1 system is that it comes with a spark arrestor, which not only makes the bike legal to ride in places (that require spark arrestors), but it also helps quiet the bike down even more and even helps shape power delivery (more on that later).

The first time I took the bike to the track with the new exhaust I left out the spark arrestor and I noticed a slightly freer feeling from the engine (note: I was using the “Keefer free feeling” map found here https://www.keeferinctesting.com/motocross-testing/2019/7/22/2020-yamaha-yz250f-on-track-facts-and-figures). This is due to the FMF muffler core being larger in diameter and having less back pressure than stock. This slightly took away from the torquey bottom end as well as a little of the mid range RPM response, but pulled a little further into the top end. After riding the bike for a while with the exhaust wide open, I decided to give the spark arrestor a try after talking to Kris. He explained that some bikes need more back pressure to make the engine preform at its best. Just like he said, after putting the spark arrestor/insert inside, it gave the Yamaha some more back pressure, which really helped the bottom end power out of corners. The bottom end pull was slightly better than stock and the mid range pull was slightly longer, but I felt that the over-rev went back to being as good as the stock exhaust. In my opinion the OEM’s have been very good at perfecting the stock exhaust systems as of late and it has made it harder for companies to make giant gains over the entire RPM range of the stock equipment. That being said FMF has done a great job squeezing every bit of power out of the 4.1 system. Having the removable spark arrestor makes it nice to not only be trail legal, but it gives you the option of creating slightly more torque (insert in) or slightly more over-rev power (insert out). FMF also works with Kris on settings as they will send some pieces for him to try to see what his feedback is. If you know Keefer, then you know he doesn't give a shit about a dyno chart, he wants real world “on track” testing and FMF has been doing this.   

I have been running the 4.1 system for over 10 hours and it isn’t showing any signs of getting louder or raspy. For my personal preference I have been keeping the spark arrestor in because I prefer slightly more torque on my 250F’s. The insert is easy to take in and out using a pick or small screw driver and removing or installing the spiral snap ring. The only physical signs of wear the system has shown is the sticker on the end cap has started to melt and bubble. From my experience this is normal after multiple hours of being ridden hard, but you can purchase new stickers from FMF. It’s also to be noted that keeping your muffler packed with quality muffler packing is key to its performance on the track. We go as long as 20 hours on FMF muffler packing, but will not go much more than that because of performance loss. FMF doesn't have a re-furbing center, so doing it yourself is your only option. 

We will be putting this system up against the competitors soon in a small exhaust shootout so be on the lookout for that. If you have any questions about the FMF 4.1 on the Yamaha YZ250F, please email me at Michael@keeferinctesting.com and I can try to help out as much as I can. 

Twin Air Power Flow Filter Kit (Yamaha YZ450F)

 If you want to get rid of the somewhat janky stock air filter cage system of the 2018-2020 YZ450F, go with the Twin Air Power Flow Filter Kit. To me the Twin Air YZ450F PowerFlow kit is the best all-around filter system for the YZ450F airbox. Why? With this kit, Twin Air replaces the stock sealing ring with an anodized aluminum mounting plate, gets rid of the backfire screen for uninterrupted airflow, adds an internal filter cage (that supports a bigger air filter), and finishes it off with a CNC-machined aluminum knob to hold the filter in place. This design brings in more air volume, increased air velocity, better sealing around the edges and better throttle response/bottom end pulling power. Yes, that is right, you will notice more rpm response out of corners as well as better pulling power out of soft loamy berms. 

The downside is that some dirt particles are more prone to fall into your air boot if you're not careful with removing a dirty filter. The reason why it’s more sucbseptble to dirt particles is because Twin Air doesn't incorporate the backfire screen and unless you have a super steady hand, a few pieces of dirt can get down inside your air boot. If you do find yourself in that situation simply get a shop vac (with a skinny end/attachment) and suck out any particles that have found its way inside the air boot. If you DO NOT open/twist your throttle after the particles have found its way inside the air boot, you will get nothing past the throttle body and you’re engine will not get any dirt inside of it. The Twin Air Power Flow Kit takes a little more patience when changing filters, but can add power to your YZ450F as well as create a better sealing surface.

The cost of $259.95 is on the steep side, but if adding up dollars to the horsepower increase we witnessed on the dyno (as well as felt on the track), the price tag is worth the almost one horsepower you will be gaining. One horsepower may not seem like much, but just think that some muffler systems (with a price tag of $1000.00) can’t get you one full horsepower. You can check out the Power Flow Kit over at twinair.com. 

If you have any questions about this test please feel free to email me at kris@keeferinctesting.com. 

WP XACT Pro Components Real World Review

When deciding to spend a few thousand extra dollars on suspension for your ten thousand dollar KTM/Husqvarna, you want to know if it’s going to make a difference immediately. Is it going to make me a better rider? Will I be able to ride faster with it? Do the WP’s XACT Pro Components that much better than stock? These are a few of the questions I get when the consumer is trying to make a decision on getting a set of WP XACT Pro Components. I have pounded hundreds of laps and a ton of hours on the stock WP AER fork/shock as well as the XACT Pro Components (on the 2020 KTM 450 SX-F and Husqvarna FC450) to see if it’s worth the risk of your wife losing her mind when she sees the charge on the bank statement. 

What Are WP XACT Pro Components and what are the differences between older WP Cone Valve/Trax components? 

WP's Pro Components line is aftermarket suspension designed for riders who want the highest quality components and are willing to pay a reasonable amount of money for them. Pro Components are manufactured to tight tolerances using high quality materials, fine surface finishes, and low-friction coatings. This reduces friction compared to WP’s OEM suspension components, and is perhaps their most significant advantage. In fact, to achieve a similar feeling of stiffness to the OEM suspension, all Pro Components required much stiffer damping. The additional stiction in the OEM components is all due to friction. Friction is perhaps the one thing in suspension where no compromise is involved: less friction is always better. When setup appropriately for the rider, Pro Components can deliver high confidence at high speeds.

The Xact Pro fork is the next evolution in "Cone Valve" technology. It retains the same Cone Valve technology and is available in three basic variants: closed cartridge with coil springs, closed cartridge with air spring, and open cartridge with coil springs. The Cone Valve itself is nothing too extraordinary as it's simply a shimless mid-valve. The cup-in-cone valve actuates via a coil spring, providing the variable orifice function that shims normally handle. The Cone Valve spring rate is linear, unlike shims which are more progressive. Also unlike shims, it does not have a maximum safe deflection distance. It can be setup stiffer and with less float than a shimmed valve without getting too much of a rigid handling ride.

The Xact Pro shock features an updated version of the Trax mechanism used in previous Trax shocks. WP’s Trax system is created to reduce rebound damping when the rear wheel is off the ground, helping get the tire back to traction as quickly as possible. The Trax system is now externally adjustable with a screwdriver, which makes the Trax function much easier to use and understand. The shock uses the same high-end construction as the Xact Pro fork and as a result, it sees a similar reduction in friction compared to OEM shock. It uses a nitrogen bladder instead of a piston separator, which has lower friction, but can require more frequent services compared to WP’s traditional piston separator setup. As with past Trax shocks, it separates high-speed compression and low-speed compression into two separate adjusters instead of one dual compression control (DCC) adjuster. The Trax shock shaft includes a rebound separator valve, which isolates compression and rebound adjustments, and increases low speed compression damping at the mid-valve (which can aid in pressure balance)

 WP’s XACT Pro Components are usually found on all of my KTM’s and Husqvarna’s I race with. Why? I get more consistency and performance out of the XACT Pro Components than that of the stock AER fork/stock WP shock. I tested the stock suspension settings on the 2020 KTM 450 SX-F back to back with the WP Pro Components and came away with this opinion: 

On The Track:

The first thing I noticed when I go out onto any type of track with the XACT fork is that the KTM turns slightly slower than the AER fork on initial lean (into corners), which is exactly what out of the KTM. The KTM does have a slightly rigid feel to it and can be a handful when riding fast, choppy tracks. You can actually feel the extra weight right away (in the front end) compared to the stock AER fork, but it wasn't a bad feeling. I was just surprised I could feel it as much when entering corners. Usually I run the fork flush on previous Cone Valve forks, but with the slower turn in feel and a the longer length of the new style XACT fork I went with a 5mm height. Along with the extra weight feeling however I gained more front end traction through every corner (especially flat corners). The XACT fork leaves you with a more front tire contact patch sensation on lean angle and you can start your lean earlier in ruts without getting the high front end, vague feeling like you do with the AER fork. With the AER fork I get some pushing in the front end through the middle to end of corners, which made makes me roll off the throttle to try and compensate. With the XACT fork I can lean in the corner and the fork stays planted, which lets my front end settle and bite. The WP XACT fork also feels less active on braking bumps. I am able to jump in and out of bigger bumps that each track I tested at offered, without having the fork rebound too quick and be too active. If I wanted to pound through the bumps, the fork had better damping control feeling through the middle to end part of the stroke. 

The most notable change was to my wrists when over jumping/flat landing with the XACT fork. I could get more aggressive with obstacles and have the bike settle into corners better in areas of the track I wasn't able to with the stock suspension. The downside to the XACT fork is that it can make the KTM feel like it has less flex up near the head tube area. This feeling is not as rigid as a Honda CRF450R, but it does give you a firmer feel through your hands on small bumps, compared to the AER fork. The key to the WP XACT fork is getting it set up for you. WP does a great job of getting you the XACT fork with a “ballpark” setting, but going through an authorized dealer that can set it up for your personal needs is the best way to ensure your investment works the best. I tested the XACT fork with their customer setting and although it was better than stock, I could have used a little more hold up on hard braking or when their was deeper braking bumps.

The XACT shock holds up better than the stock shock for me on high speed compression and you are able to get more aggressive around the track. I can hit the faces of jumps harder and the KTM did not give me an empty/low feeling sensation that the stock shock sometimes gave me. In order to combat that feeling with the stock shock I would have to crank in the high speed compression so much that I would lose the comfort coming out of corners (and rear wheel traction). The XACT Pro shock provides you with more high-speed damping and you still get a decent amount of acceleration comfort on choppy corner exits. I also noticed a little more connectivity to the the rear wheel (when hard on the gas) on flat corners with the XACT Pro shock compared to the stock shock. The XACT Pro shock is firmer so there is less wallow in the rear end when accelerating, so the rear of the KTM 450 SX-F tracks straighter and doesn't upset the KTM’s chassis as much at speed. “Balanced” is a great word to describe both ends of the KTM, but I did notice the harder I pushed the more it rewarded me. If I tried to ride smoother/slower, the action of the shock wasn't quite as comfortable as the stock shock. This XACT Pro likes to be pushed and will reward the rider that is aggressive because of its much more consistent nature (compared to the stock shock). Again, going to a WP authorized dealer and having it set up for you is key. Thinking that you’re just going to go purchase A-Kit level suspension, slap it on, and then magically be in heaven on the track is completely foolish! Get it set up for your weight, riding ability, and the type of rider you are will ensure that your money is spent correctly. 

Conclusion:

Do you “need” these WP Pro Components on your machine? If you’re a casual rider, of course not. However if you’re a KTM/Husqvarna rider and race consistently, I think the WP Pro Components are worth the price. For around $3499.00 for the fork and $2199.00 for the shock it’s an investment that you should take seriously. If it was me, had one bike, was on either a KTM or Husqvarna, I would invest in a set of WP Pro Components because when I ride/race, I want the most consistent feel I can get. I also know that if you are the type of rider that gets a new KTM/Husqvarna every couple years, you’re able to roll these WP Pro Components over to your new bike. This is an investment that you can continue to roll over with each passing model year. I think it’s safe to say that KTM or Husqvarna will not change their motocross models until the year 2022, so your WP Pro Components will fit at least until then. Even if KTM/Husqvarna change their machines drastically, chances are these newer WP Pro Components will bolt on. 

FAQ: 

“Keefer, have you tried a set of standard re-valved WP AER forks and shock”? The answer is yes and although the comfort was improved (over the standard/stock set of suspension), the consistency just wasn't as good as the WP Pro Components. I would say that a set of stock re-valved stuff will definitely be good for your local racer that simply can’t afford new Pro Components. Companies like Race Tech, Kreft, and Enzo all have very good re-valved stock suspension settings. 

“Keefer, is there something I can do about the rigidity I am gaining with the WP XACT Pro Component fork”? Yes, going to a WP/KTM Factory Triple Clamp will help with some of the rigidity that the stock clamps come with. Also, you can go to a bottom triple clamp torque spec of 9N/m. Both will help with comfort on braking bumps, slap downs, as well as get you less rigidity feel through your handlebars. 

If you have any questions about this test, feel free to email me at kris@keeferinctesting.com 

FMF Vs. Pro Circuit (2020 Yamaha YZ450F Muffler Comparison)

Yamaha did a great job with the stock muffler and I bet if you ask any aftermarket muffler manufacturer they would tell you the same thing. If you’ve seen my social media pictures while riding the Yamaha YZ450F, you will see that I run the stock system quite a bit. Why? Because it’s really good! However, I know some of you out there will not keep the stock system on your bike because you may want something lighter, more attractive, and hopefully get something with more power than the stock system right? That is why I went to work and really picked apart the FMF and Pro Circuit systems for the bLU cRU machine. I do know that FMF and Pro Circuit have been working really hard on continuing to improve/evolve their systems for the YZ450F and after riding a ton on each, here are some of my findings.    

Pro Circuit Ti-6 Pro Versus Stock: 

Why The Ti-6 Pro? I chose the “pro” because of the smaller insert that it comes with to pass AMA/FIM sound because I have come to find out that the YZ450F loves back pressure and that smaller insert helps with throttle connection. The exhaust note on the Pro Circuit Ti-6 Pro is not near as loud or raspy sounding as the Ti-6 or T6 so that is another reason why I chose the “pro”. The exhaust note on the “pro” is deeper and slightly quieter, which I personally like more. The power delivery is slightly smoother than stock on very low RPM (4000-6000 RPM), but is only noticeable to very sensitive riders. At 10-15% throttle position there is a slightly softer RPM response, which I didn't mind on nasty, dry, choppy tracks in Southern California. If I needed more bottom on softer tracks, I simply ran a more aggressive map and that helped the “pop” I was looking for out of corners. I usually ran the TP 3.0 map with the Pro Circuit system and it made me happy with the amount of smooth roll on power I had. If you’re looking for more excitement down low and out of corners, try the “Exciting Power Character” map. (https://www.keeferinctesting.com/motocross-testing/2019/9/18/2020-yamaha-yz450f-start-upbaseline-settingstipstricks)

The rear wheel definitely feels more connected to my throttle hand and in comparison the PC system has a more seamless power delivery when transitioning to its mid range pull. The mid-range is where I could stand to get a little more power and this is exactly where the PC system delivers. The meat of the Ti-6 Pro’s power while accelerating down the next straight is noticeably better than stock. I am able to use third gear with the PC system (compared to using second gear with the stock muffler) and even though the low RPM response is slightly softer than the stock system, the mid-range RPM response is much more instant. Mid-range rpm response is crisp and makes the Yamaha feel “lighter” when trying to hop over square edge choppy areas of the track when accelerating. 

I talk a lot about using third gear on a 450 and if the bike is able to pull that gear through corners. The stock YZ450F does this very good and I was worried that putting an aftermarket muffler on would hurt this feeling. The PC system only improves this as I noticed that have been able to use lower RPM’s around the track with lower lap times. I like that I feel that I can work the clutch/shifter less with the PC system. 

Top end pulling power is as good as stock, but the PC Ti-6 Pro doesn’t have the over-rev the stock system has. If you learn to short shift the PC more and let that newfound mid range meat pull you around the track you will appreciate the phrase “work smarter, not harder” a lot more. I was impressed how the Pro Circuit Ti-6 Pro delivered as well as spread out its power and to me, made the Yamaha even more fun to ride. If that’s possible? For you weight watchers out there, you will lose around 1.2 pounds from the stock system and the PC Ti-6 Pro Titanium System runs $1,118.21. You can go to procircuit.com to get yours. 

FMF 4.1 Versus Stock:

The FMF 4.1 muffler system has a deeper more throaty sound to it (over stock) and has a louder pitch than the stock muffler system. On the track, the FMF 4.1 (on the YZ450F) makes almost as much bottom end power delivery as the stock system and keeps that peppy/exciting RPM response. The stock system has more pulling power immediately out of corners, but the FMF 4.1 allows for better traction while rolling the throttle on when the track gets slippery. Where the FMF 4.1 system really impressed me was mid range pulling power when exiting corners. The stock system is excellent in this area, but has a heavy mid range rev feel. The FMF makes the YZ450F’s engine feel free-er and gives the rider a snappier yet more powerful mid range pull with less engine braking.  

I stuck with the “TP 3.0” and “Exciting Power Character” maps on the FMF 4.1 system and that let me choose what kind of power delivery I needed at any given time of the day. With those maps and the 4.1 system you can control the power a little more down low and allow the Yamaha to have a more linear feel in second and third gear. The FMF 4.1 system has a larger muffler opening when you un-box it so make sure not to throw away your insert/spark arrestor screen that FMF includes in the box. If you think you want a little more excitement (bottom end) back into your YZ450F, simply install the insert (with the screen) and the Yamaha will get more back pressure and some more connection/bottom end pull/low rpm response, but you will lose a little of that mid range free feel that you gained.  

Up on top end the FMF pulls harder than the stock system, but falls a little short when it comes to the over-rev department. The 4.1 accepts short shifting, so if you’re like me and love to get into third gear as soon as you can, the FMF does accept that third gear shift a little earlier than stock as well. I like that FMF keeps evolving their systems with each passing model year and to me the 2020 system has some added mid range pulling power that the 2019 didn’t. The FMF 4.1 Ti muffler system will save you 1.5 pounds over stock and the cost of the FMF 4.1 titanium system runs $1099.99. You can go to fmfracing.com to get yours.


Pro Circuit Vs. FMF: 

Let me start off by saying that these are two muffler systems (for this model) that will rival or surpass (in spots) the stock system’s performance. That’s not easy to do! Some muffler manufacturers have better performance or have come up with a better setting for certain models and Pro Circuit as well as FMF have done a great job with their 2020 YZ450F system. The Pro Circuit has a little more throttle to rear wheel connection down on low end, but the FMF pulls stronger through the mid range. Up on top end both seem on par with each other and of course both have less over-rev than the stock muffler. I can lug the YZ450F in third gear more with the Pro Circuit muffler, but the FMF has more of a free feeling to it when higher up in the rpm range. These muffler systems are close in comparison to one another and offer the rider a different power curve than stock that is actually beneficial to the Yamaha YZ450F rider. 

Results:

Bottom End Pull: Pro Circuit

Mid-Range Pull:  FMF

Top End Pull:      FMF/Pro Circuit

Over-Rev:   Stock

Bottom End RPM Response: Stock

Mid RPM Response: Pro Circuit

Top End RPM Response: FMF 

Best Looking: FMF

Stock Heat Shield Mounting: FMF, Yes/Pro Circuit, No

Fire Power Parts Review

Fire Power Featherweight Lithium Ion Polymer Battery

Fire Power lithium batteries are for use in Powersports vehicles only (motorcycle, scooter, ATV/UTV). Fire Power batteries are direct replacement batteries for your vehicles original battery. Fire Power batteries have Lithium Ion Polymer technology and all components are designed, manufactured, assembled and packed in one location assuring high quality and consistency. The Fire Power battery that has been in our Yamaha YZ250F is extremely lightweight at 1.06 pounds (stock is 1.5 pounds), has a built-in LED test gauge so you know when your battery is at full charge, half full, or has a low charge. I also noticed that the Fire Power battery has increased cranking amps over a lead acid battery that I tried in my dad’s older Honda. I have yet to recharge a Fire Power, but from what I was told (from my test rider Michael Allen) that the recharge time literally took him 7.5 minutes in order to get the battery up to 90% charge. Fire Power was claiming six minutes, but nonetheless that is a damn quick charge and not to mention that you can charge it with any 12 volt battery charger as long as it has automatic turn off capabilities. 

The lifespan of the Fire Power has been much better than that of our stock 2019 Yamaha YZ250F battery, as we are still on the same FP from last winter. Just for the sake of testing I ordered a new Fire Power battery and have let it sit for almost one year and it still is holding a full charge. I will say that we haven't had too many cold nights here in Southern California, but after having two dead stock batteries in my Yamaha as well as my KTM/Husqvarna in that same span, the Fire Power is doing great in my book. Another aspect that I didn't know too much about, but is a cool feature is that the Fire Power can be mounted in any position, just in case you’re trying to modify or get more room out of your airbox like my good buddy Gary Sutherlin did with his Yamaha YZ450FX back in the day. The Fire Power has no hazardous acid or heavy metals, it’s non-explosive and non-combustible. It comes with a two year warranty and will only cost you around a $100.00.

Fire Power Heavy Duty Chain

I go through chains a lot because most of the time I am a non o-ring type of moto rider. I also know that cheap chains are very unsafe and I have broken more than a couple in my time. NOT COOL!! There is nothing more scary than snapping a chain while you're taking off from a jump. I have been a huge DID ERT2 fan for as long as I can remember because I have had the best luck with those specific chains. Switching to a Fire Power chain was something that quite frankly I wasn’t too sure of… Until now… 

The Fire Power Heavy Duty chain is designed and manufactured in Japan, has an 8,000 pound tensile strength, comes in a 428/520 pitch, has hardened/shot peened components with solid rollers, comes pre-stretched, and all Fire Power chains are supplied with clip style master links. I usually just get a 120 link chain and cut to my desired length so that I can place my rear wheel where I like it. Once installed the Fire Power chain will initially stretch the first couple times out and then I literally didn't touch it for a solid 4-5 engine hours. I keep it lubed before every ride and it has treated me well. I have ridden with the Fire Power chain on my YZ450F, KX450, as well as the KTM 450 SX-F with the same results. Conditions have been from sand, mud, dry silt, and the occasional trail ride from the house.

Under those conditions I have gone anywhere between 10-18 hours on chains in the past and the Fire Power chain is on it’s 16th hour. Around the 16th hour I felt like it was loose enough to where I decided to retire it (per my judgement) and install a fresh one. To get a chain that I can trust in that amount of time for under $50.00 is almost unheard of. I would recommend the 520 Fire Power Heavy Duty Gold Chain to any weekend warrior looking to save some money and get a quality product.  

If you have any questions about the Fire Power products in this test, please feel free to email me at kris@keeferinctesting.com 

Akrapovic Evolution Muffler System (2020 Honda CRF450R)

This is embarrassing, but I am going to be completely honest here… I think about the Honda CRF450R a lot. More than other machines. I mean I will literally wake up in the middle of the night and think of things to test in order to try and make the Honda chassis calm down a little because I see so much potential in this bike, but I need it to be calmer. It turns incredible, has an insane amount of power, and has the best ergonomics of any bike, but it lacks some comfort and predictability to me at speed. This drives me crazy because I really like this damn bike a lot! 

I stumbled across the Akrapovic Evolution muffler system as I was doing some ECU mapping with Chad at XPR Motorsports on the CRF450R. Chad does the engines for the MotoConcepts/Bullfrog Spas Honda team and I noticed that they have been running Akrapovic systems on their bikes, so I asked if I could borrow one to see how it worked. Akrapovic's Evolution line is their full titanium muffler system and includes more in the complete package than other system that I have unwrapped. The welds are beautiful and to me the quality of the complete system is second to none. Installing the Akrapovic takes a little bit of finagling, but with some patience it does line up and fit well, as long as you leave most of the bolts loose when installing. Also included in the system are some extra parts, such as a carbon fiber guard, which protects the headpipe and resonance chamber from side impact. There’s also the hardware needed for the guard, along with some extra pipe springs and rubber grommets/spacers for the exhaust cans, as well as a set of quiet/spark arrestor inserts. Keep those in (more on that later). 

Once out on the track is when I realized that this Akrapovic muffler system could actually help this Honda chassis calm down. The Evolution system lets the Honda’s engine roll on smoother at low RPM’s and that smoother feel helps the rear wheel connection as well as provides less pitching (off throttle) than the stock system. AKA MORE COMFORT!!! The Honda CRF450R now builds a smoother roll delivery and a pulling power that is longer through the mid range than the stock system. This type of character can allow you to use second gear in corners more because the second gear hit is not as abrupt or quick and that doesn't upset your technique or the chassis. The Akrapovic also allows the rider to shift later out of the corner with its increased over-rev capabilities. Pulling power up top is increased slightly as your shifting points can be altered now because of the longer pull in each gear. The mid range recovery of the Akrapovic is not as good as the stock system, but honestly that is not a bad thing. The Honda has so much power to work with that a little less “hit” as well as “recovery” actually helps me roll my corners better and allows me to be more aggressive on the Honda. I want to be able to ride this red bike and not let it ride me after 15 minutes into a moto. The Akrapovic system relaxes the engine as well off throttle. There is not nearly as much engine braking with the Evolution system and that also helps your fork from feeling harsh on small de-cel bumps.  

The pitch of the Akrapovic is ridiculously quiet when on the track and will almost give you that MXGP sound and feel. It still has that racey, crisp sound, but just not that raspy high pitch tone of the stock muffler. I preferred the quiet inserts left in because it created more back pressure and gave me more traction at the rear wheel (out of corners) in all three engine modes. I was normally a map two guy with the stock muffler, but with the Akrapovic installed I am now a map one guy all day long because of the added rear wheel/friendlier connection. 

At just over 8 pounds the system will save you almost 1.5 pounds over stock and will set you back a whopping $1547.00! Is the cost worth it? I wouldn't go that far, but it is one of the better muffler systems that I have tried on the Honda CRF450R. If I was a Honda owner I would rather invest in a Vortex ECU, have it mapped, and save a few hundred bucks, because the Vortex ECU can do more to help the power character/chassis feel than that of the Akrapovic sytem. However, if you do have a deep pocket book and are going to get a muffler system anyway, this Akrapovic would be a great choice. It’s a beautiful system and works very well on a wide variety of terrain/tracks. 

Go to akrapovic.com to locate your nearest dealer. 

Wrench Rabbit Yamaha YZ125 Engine Rebuild Kit

By Michael Allen:

Although one of the main perks or being a part of Keefer Inc. Testing is getting to ride the latest and greatest bikes, there are times when you need to have your own bike. I needed my own bike because I was going to race the Los Ancianos Tecate Enduro that is run in Mexico and I needed to be able to show proof of registration. After a lot of looking around I found the perfect bike, a somewhat abused 2006 YZ 125. I raced it for two years in Mexico and would randomly ride it here and there when I wanted to feel like I was going fast. Here is where the embarrassing part comes in, this last winter we had an abnormal amount of rain in California, which was great, but I was admittedly a little lazy in the maintenance department.  I figured “it’s wet, how dirty could my air filter be getting”? Well after not checking my air filter for about three rides, my $1,800 Yamaha YZ125 decided to come to a quick stop in the middle of a snowy trail ride. As I was on the pipe climbing a sandy canyon the wheel locked up and I came to a skidding stop. I luckily was within pushing/coasting distance back to the truck, but when I got there and pulled the seat off, I immediately knew what happened and felt really stupid. You see when I got the bike I did the current plastic re-style kit from Polisport and when I re-installed the air box, apparently I didn’t do a good job with the hose clamp (that holds the air filter cage onto the air box). To my surprise my air filter and cage was just sitting in the bottom of the air box and I had been sucking dirt into the engine for who knows how long. Fail!  

Needless to say when I tore the engine down there was grit everywhere from top to bottom. I knew if I wanted to do it right the whole engine would need to be rebuilt, but I also knew that replacing bearings, seals, gaskets, a top end, and crank with OEM parts would cost more than I purchased the bike for. After talking to Kris he mentioned that Wrench Rabbit sells complete engine rebuild kits and from what he remembered they weren’t all that expensive. After that conversation with Kris, I reached out to them and got the ball rolling on rebuilding my little 125. 

The Wrench Rabbit kit (Part Number WR101-081) really does come with EVERY bearing, seal, and gasket you need to do a complete rebuild on your bike. To be completely honest I had done a bunch of top ends on previous two-strokes, but this was my first time splitting cases and doing my own rebuild. I took it slow and really tried to do good job of keeping everything organized when I took it apart. Upon disassembly it was then that I realized that it wasn’t as scary as I imagined it would be. When the engine was torn down I found that my issues were a scored piston (luckily the cylinder wasn’t bad enough that it needed to be re-plated or replaced), a blown out rod bearing, and main bearings that were ready to come apart at any time. The Wrench Rabbit kit comes with a brand new crank/rod from Hot Rods already assembled as well as new main bearings to go with it. In the past I had been scared to use aftermarket engine parts, but the quality of the Wrench Rabbit parts were very impressive and every part fit just as good as the factory parts that came out of the bike. 

As I buttoned up the cases and slid the cylinder onto the new Vertex piston I was pretty excited to get my 125 running after looking at it sit in the garage for the past five months. I slapped the engine back into the frame at about 11pm and was so excited to get it running I ran to the gas station that night to mix some gas and wake up my neighbors. The child like smile on my 32 year old face said it all when it came to life on the third kick and I was able to take it down the street for an initial heat cycle a midnight. After a few more heat cycles I was able to moto down and I’m happy to report that my 125 runs better than ever. In fact, the rebuild is done just in time for me to head back down to Mexico in about a month for more trails, tacos, and beer. 

I learned three main things from this whole process… The first lesson is to never be lazy about maintenance, no matter how well you think you know your bike. The second is to not be scared to do your own bike work, even if you have never done it before. With an OEM Owner’s Manual and a proper set off tools, you are more capable than you may think. I did go out and buy a Motion Pro case splitter (Part # 08-0605), a Motion Pro flywheel puller (Part # 08-0026), Motion Pro bearing driver set (Part # 08-0551), and some Yamabond Liquid Gasket (Part # ACC-BOND4-MC-00) to make the rebuild a little easier  The third and most important is to not shy away from quality aftermarket parts. After adding it up, I saved over $350.00 by using Wrench Rabbit parts. OEM parts are great, if you can afford it, but finding quality aftermarket parts are like riding a unicorn and by the looks and sound of my YZ125, I have found Pegasus. With all the parts supplied, the Wrench Rabbit kit only set me back $514.95. Reason #158 why I love two-strokes! So if you have either a worn out engine (no matter two or four stroke), or in my case are an idiot and blew your bike up because of negligence, give Wrench Rabbit a try, you won’t be disappointed. Also keep in mind that Wrench rabbit doesn’t just have kits for engines, in fact they offer replacement parts for all facets of rebuilding a motorcycle.  You can email me if you’re interested in ordering some parts and getting the Keefer Inc. discount. michael@keeferinctesting.com.

OR YOU CAN CLICK ON www.wrenchrabbit.com TO SEE WHAT PARTS YOU MAY NEED.

Yamaha YZ125 Wrenh Rabbit Kit Part Number WR101-081 ($514.95) includes-

• Vertex piston kit (standard compression piston, rings, pin and clips).

  • Premium quality Vertex piston.

  • Complete set of nitride coated or chrome-plated piston rings.

  • Fully case-hardened wrist pin.

  • Circlips.

• Hot Rods heavy-duty crank (stock stroke - includes wrist pin bearing for two strokes).

  • Factory assembled and trued to O.E.M. specifications, Hot Rods cranks will meet or surpass the O.E.M. in performance and durability.

• Hot Rods main bearing / seal kit.

  • Like other Hot Rods products, these main bearing and seal kits are built to the highest quality standards that meet or exceed those of the O.E.M.

• Hot Rods transmission bearing kit (includes transmission bearings, output shaft collar and sprocket lock washer).

  • A must-have for any new transmission or engine case installation or repair.

  • Includes trusted Hot Rods bearings for the primary and secondary shafts of the transmission.

  • Also includes the special needle bearing for the shift drum and the output shaft collar and washer (where applicable).

• Hot Rods counter balancer bearing kit.

  • A must-have for any new counter balancer or engine case installation or repair.

  • Includes trusted Hot Rods bearings for the counter balancer shaft of most modern 4-stroke engines (where applicable).

• Hot Rods water pump bearing and seal kit.

  • Hot Rods water pump repair kit includes water pump cover gasket or O-ring, water pump shaft bearing(s), and seal(s) to repair a leaking water pump seal and/or a failed bearing.

  • Precision micro-bearings provide O.E. quality and durability.

  • High pressure / temperature mechanical and rubber seals.

• Hot Cams cam chain.

  • Replacement cam chain.

  • Meets or exceeds O.E.M. specifications.

• Vertex complete gasket kit, including seals and O-ring kit (covers top and bottom).
  

Tools For The Job: 

• Motion Pro Case splitter Part # 08-0605

• Motion Pro Flywheel puller Part # 08-0026

• Motion Pro Bearing driver kit Part # 08-0551

• Yamabond gasket maker Part # ACC-BOND4-MC-00

FMF Factory Fatty Pipe/Shorty Silencer (2020 KTM 125SX)

Since the delivery of our KTM 125 SX, my son Aden has been riding it non stop. He also has been barking in my ear about getting a pipe and silencer so it “sounds cool”. While I am usually reluctant to add parts to my kid’s bike for the sake of just doing it, I thought this could be a good way to test a pipe and silencer to see if it actually helps the Austrian two stroke power plant. After I discussed “the conditions” to my kid, I called upon Lil D and the boys at FMF to send me a Factory Fatty pipe and Shorty silencer to try. 

What were Aden’s “conditions”? The conditions were that he had to install the FMF products and help me write this test. I took it upon myself to ride the 2020 KTM 125 SX in stock form as well as with the FMF Factory Fatty/Shorty combo at couple tracks. The installation was fairly painless for my 13 year old. He learned how to use a spring puller for the first time as well as how to push the rubber grommets through the silencer mounting points without stabbing himself with a flat blade screwdriver. Once he got the FMF pipe/silencer installed he of course had to start his bike and see how it sounded and I will have to admit, it sounds pretty bad ass. The pitch of the KTM 125 SX with the FMF pipe/silencer is more of a crisp/barking sound rather than a richer/raspy sound that the stock pipe/silencer comes with. Ok, now that we smoked out the garage and pissed mom off, we loaded up the bike and went riding! 

I went back and forth with the stock set up as well as the FMF a couple times at a few different tracks and I will say that the FMF Factory Fatty pipe/Shorty silencer combo did help throttle response as well as low end grunt. Coming out of corners (with the FMF Fatty/Shorty) the KTM 125 SX has a little more acceleration pull on corner exits and could be shifted a little earlier without falling off. The mid range pull was also longer and overall crispness of the mid range seemed improved. The FMF Fatty/Shorty seemed to lean out the bottom to mid range (in a good way) and made the KTM feel more playful around the track. RPM response was improved throughout the power and the throttle felt more connected to the rear wheel. 

The top end pulling power/over-rev was slightly shorter than the stock set up so I wanted to play with jetting to see if I could get some of that back. I went back and forth on a few different main jets as well as needle jets, but came back to this set up below: 

Jetting Specs:

Needle position: 3rd position from top

Jet needle: 6BFY43‑71 

Main Jet: 520 (500 Stock)

Idling Jet: 35 

Choke nozzle: 80

Needle Jet: S‑7

Idle Air Adjusting Screw: 1.5 turns out/open

With this jetting the KTM 125 SX pulled longer up top and gave Aden/I more over-rev in 2nd-3rd gears. To me these two gears are the most important for Aden as he learns how to improve his corner speed as well as technique. Sometimes Aden will leave it in second or third gear too long (instead of shifting) and having this jetting allows the KTM 125 SX to pull a little longer. This jetting was good for sea level up to 3500ft. Anything higher than 3500 feet elevation and I would go back up to the 2nd needle position. 

Overall, there is some performance gains to be had with the FMF Factory Fatty/Shorty Silencer. Aden has put over 14 hours on the system and the silencer still sounds good and not blown out. He did manage to put a small ding in the bottom of his pipe and that made him mad, but he’s ok with it after he took some WD-40 and Scotch Brite to the thing! Proud dad moment! The Fatty is $249.99 and the Shorty costs $134.99. A lot les expensive than a four-stroke system! 

Below is Aden’s opinion of the FMF and stock pipe/silencer. I wanted to let him have free range on what to talk about, so he can try to get better at communicating his thoughts into a testing format. During the course of this test I never shared my thoughts about the FMF Fatty/Shorty for confidential purposes. His opinion is unedited, but I did clean up a few grammatical errors for the sake of reading. After reading his opinion, I couldn't help but write down my thoughts about his opinion. It seemed too good not to share with you all. Enjoy! 

Aden Keefer Opinion: 

The differences between the stock pipe vs the FMF Fatty/Shorty pipe is that the FMF pipe hits stronger coming out of corners, but on the other hand the stock pipe is a little bit more linear coming out of corners. The stock pipe takes a while for the power to kick in which was ok on hard pack desert tracks that I rode. I did like the FMF pipe more because it was aggressive and you can put the bike anywhere knowing that it’s gonna have the little extra power. The one reason I do like the stock pipe is that since it’s more of a longer silencer I can control it better when I get tired because it’s not so aggressive. Don't get me wrong though! I think the FMF pipe and silencer is one of the best pipes out there. Not does it only make your KTM 125 SX faster, it makes it look super cool and it sounds way better than the stock pipe. I also noticed when we put VP C12 in the stock pipe/silencer it made it run aggressive, but when we also tried out VP C12 with the FMF pipe/silencer it ran like a race bike. It made it so fast that I was pulling all the 450’s going up Mt.St.Helens at Glen Helen. I also think cleaning the FMF pipe/silencer is rewarding. My dad loves to vacuum because he said he can see his progress with his work. I like cleaning my FMF pipe and silencer because I can see my progress as I scrub it with an SOS pad. So to wrap this up, I think that the FMF pipe and silencer is the best pipe out there for any 125's out there.

Dad’s Thoughts About Aden’s Opinion: 

-I appreciate some of these testing comments and at least it shows that he is listening to me a little. So you’re saying there’s a chance! Hallelujah!  

-I like that he could feel that the FMF Fatty/Shorty had more bottom end. That shows me that any kid could install this product and feel the difference. 

-It’s funny that he recognizes how the KTM works on different terrain and can appreciate a smoother power at times. I am glad he’s not a balls out rider! Safety first!

-Pulling 450’s up MT. Saint Helens? Eaaaaaaasy there tiger!

-Of course when I was his age I also thought something that was aftermarket was way cooler! Why? Because it wasn't stock! Duh! After reading his opinion it seems that he’s into the styling of the “Raw Fatty look”. Me too, Aden, me too! 

-Here we go with the C12 talk again! That is all this kid was talking about for a few weeks! “Dad, let’s get some C-12”! “Dad, let’s get some C-12”! I broke down and got some. The C12 did make the KTM’s pulling power stronger, but also leaned it out enough to warrant the jetting change. However, the jetting change that worked with the VP C-12 also worked with pump gas too. Don’t be scared to run that jetting with either fuel. Aden wanted it because of the smell! Mom’s still mad because her kitchen smells of C12 and Maxima Formula K2. Sorry, babe! Not really, because our house smells like a race shop now! :)

-Aden coming in hot with the vacuum reference! Wow! My secret is out now. Great!

-Good job Aden. We have some work to do, but good job son! Love, Dad!