Pro Circuit T-6 Stainless System (2022 Kawasaki KX250)

The muffler on the stock 2022 KX250 sounds a little too blown out for me in stock form (even when new). The tone of the muffler is not pleasant to the ear, so I crossed my fingers, called Pro Circuit and picked up a T-6 (stainless system) Muffler System to see if it enhances the current engine character of the KX250. Ti-6 and Ti-6 Pro systems are tough to get at the moment so we settled on a stainless system, which can last longer (more durable) than a titanium system. While I had a PC system, I thought it would be cool to give you guys a run down on a couple other mufflers that I have tried on the KX250 and compare those with the PC (see below). Here’s what I came away with… 

Immediately I weighed the stock and PC T-6 mufflers and took notice of how the Pro Circuit system cut just over 0.7 pounds off the green machine so we were starting off well. The next thing that made me happy was that the PC muffler goes on easy and literally took me 7 minutes to change out! Boom! So far so good! After installation I recruited my son to help me evaluate the system as he now has a new found love for the KX250 and a Team Green ride that didn’t exist last year. I made him write his notes down and I told him we would compare both of ours after we have tested this muffler at a few different tracks. We tested the T-6 at Glen Helen, Perris, secret dez tracks and State Fair MX just so we knew exactly what we were getting out of the PC system. 

 When you purchase your T-6 muffler it will come with a spark arrester screen already installed inside the muffler. DO NOT REMOVE THIS! This helps with back pressure and gives the KX250 the RPM response and bottom end that Aden (my son) and I both like. When we took it out the PC system lost some excitement down low and lost a little bottom end. You can however punch a small hole through the back of the screen and then reinstall it. Doing this actually helps give the PC system a little more bottom end/RPM response while still retaining that back pressure that is important for rear wheel connection. 

Ok so now that we got the “tricks” out of the way, how does this PC system compare to stock?. Normally I DO NOT get more bottom end with a PC system (versus stock) on any brand of bike, but I was surprised that I got a little extra bottom end pulling power out of the PC system. RPM response is a little softer than the stock system, but when opening up the throttle out of corners the KX250 (with the PC system) pulls harder than the stocker. Mid range is where you will feel the meat of this power. When accelerating out of the corner and shifting to third, the KX250 doesn't have that “empty” feeling that the stock muffler has at times when the track is tilled deep. The PC system keeps pulling once the KX250 is shifted into third gear and continues to pull harder into the top end. Over-rev is as good as stock and I didn’t notice any loss of over-rev when swapping the two mufflers back and forth. 

 The only real negative I have found from the PC system is I wish it would have a little more low end RPM response, like the stock system. The stock muffler has such great initial touch of throttle which can make the bike feel a little lighter when hopping over bumps or popping out of blown out berms. The PC system pulls better out of corners, but is just a smoother initial touch (AKA, low end RPM response). If you want more low end RPM response and could stand to lose some pulling power then take the screen out of the T-6. Doing this will give you more low end RPM response, but will hurt some mid range and it will not sound as good in my opinion.

Overall Aden and I are pleased with the PC system for the 2021 KX250 and I guess we shouldn’t be surprised as they do have that Kawasaki race team and all. My son surprisingly felt most of the pulling power, but didn’t feel much increase anywhere else, so not bad for a 14 year old squirrel. Hey, Mitch! If you’re reading this, good job! Chanceability that he reads this? ZERO. POINT. ZERO! 

Extra Credit: We tried a HGS and FMF system just to see what we had in the Pro Circuit T-6 Muffler System. 

HGS: The HGS has a bottom end feel similar to the Pro Circuit system but not as good as a mid range pull. The HGS system has more top end than the PC and FMF system, but it takes a little work to get there. If I was riding a sand track, I could see how someone could like this system. Great top end-over-rev. 

FMF: The FMF has more bottom end than the PC system and has slightly less mid range than the PC, yet more the than the HGS. Top End is short and over-rev has slightly less. than stock. 

Yoshimura RS-12 Full Stainless System (2022 Honda CRF250R)

The 2022 Honda CRF250R is a hot commodity and an aftermarket muffler is even hotter. With COVID-19 wreaking havoc on supply, new muffler systems have been a little slow to get released to the consumer. The Yoshimura RS-12 for the 22 CRF250R should be in stock by the time you read this so let’s compile some notes and talk about some points about the new RS-12 system, before you make a 1000.00 purchase on a aftermarket muffler shall we? 

Install:

Installing the new full system took me less than 20 minutes and the instructions were very detailed. All of the parts that came inside the box fit perfectly and it was easy enough that my 15 year old son installed it! In my opinion, Yoshimura is one of the highest quality exhaust manufacturers in the industry. I have been a part of a few R&D departments and I can tell you first hand that the quality, fit and finish of a Yoshimura exhaust is impressive. I wanted the stainless full system because it was less expensive ($909.00) but is a little heavier than the stock muffler system by just over a pound. I didn’t care about weight as much as performance so stainless is fine with me! 

On The Track:

Now to the part that everyone wants to know...Does the Yoshimura help the little red screamer? The simple answer is yes, but who likes simple answers? Not us! With the stock system, the 22 CRF250R pulled nicely bottom to mid-range, but lacked some top end and over-rev. When trying to grunt up obstacles, the engine still needs some help, but the 22 CRF250R is much better than the 21 in this department. This had Yoshimura rethink their RS-12 for 22 and came in with a spec that keeps most of that bottom end/low RPM responds but added mid range meat and top end pulling power. With the stock muffler the Honda still liked to be ridden a gear lower at times in corners (than other 250F machines), and if I didn’t, it took a bit of clutch feathering and more shifting to get the bike pulling hard again.

As soon as I fired the bike up with the new RS-12 exhaust it was clearly a bit louder, not obnoxious, but a nice, throaty sound that was deeper and less raspy than the stock muffler. I tested the stock system back to back with the Yoshimura system on the same days, so it was cool to see the places on each track where the bike really felt different. The most noticeable place the bike felt better was exiting out of corners while accelerating out of tight inside ruts. With the stock system I had to slightly slip the clutch and pay attention more to my RPM’s, all the way up the lip (If there was a jump out of a corner). When I bolted on the Yoshimura system I could leave it in second gear and just use the meat of the new found Yoshimura power to pull me up and over those types of jumps. Some areas of the track I had to be in second gear and then immediately shift into third with the stock system. With the Yoshimura system I could now be in second gear and let it pull that gear longer rather than having to shift. The Yoshimura RS-12 can also recover quicker if you’re in too high of a gear through corners. The RS-12 picks up quicker and makes the bike feel a little lighter through the mid-range. On soft berms the RS-12 allows the rider to stay on top of the soft stuff better than the stock system because of that quicker rev feel. From mid to top end is where you will notice the big difference between the RS-12 and the stock system. You’re able to pull each gear longer and with a harder feeling pull when making that shift. I would even venture to say that the mid rpm response is slightly crisper when in third gear not to mention that recovery feel in third gear through deep corners is notable right away. Bolting on the Yoshimura RS-12 full system will not make your Honda more responsive down low, but I appreciate that it didn’t complete kill that newfound low end that Honda needed for 22. The best part is that the Yoshimura muffler looks much cooler than the stock ones and sounds ten time better. 

 If you have a 2022 Honda CRF250R and feel like you’d like a bit more mid-top end power, I’d definitely look into the RS-12 stainless system. Yoshimura offers three options, the slip on mufflers ($719.00), the full stainless system ($949.00), and the full titanium system ($1259.00). Admittedly none of these are super inexpensive options, but it’s one of the few things in today’s four-stroke world that can provide a true bolt on benefit. 

Brake Modifications And What They Do On The Track

You can only go as fast as your brakes allow you to slow down. That doesn’t sound quite right, does it? But if you don’t have good stopping power on your dirt bike, chances are you will not be able to get around the track or clip down that trail at any reasonable rate of speed without missing your mark or crashing. Most of today’s off-road motorcycles come stock with fairly good brakes and are usually plenty capable for 90 percent of the riders out there. But what about those 10-percenters who want just that little extra or maybe are super picky about how their brake engages or feels? We wanted to “brake” down several ways that you can alter your brakes’ performance to get the most out of that lever and pedal.

Who comes with the best stock brakes, out of all the new off-road machines? KTM has used Brembo brakes, Galfer rotors, and steel-braided brake lines for quite some time. This combination has proven to be the most powerful, yet the most progressive, way to get stopped or slowed down from an off-the-showroom dirt bike. If you’re on a Nissin brake system, using some of these modifications below will get your bike to this point, or using all of these mods will get you past it.

Fixed Or Floating?

A fixed brake rotor is a simple, solid, one-piece rotor. A fixed brake can also increase lever pressure and power but is susceptible to more warpage when hot due to its solid mounting points. Fixed rotors are lighter than a floating rotor, and, remember, rotors are unsprung weight, which is key to a bike’s handling on motocross machines. A floating rotor system uses bushings that attach a mounting bracket to the brake area where the pads grab. The bushings offer a slight bit of play, allowing for a more centered or equal grab by pads, leading to more even pad wear. Also, in case of an impact, floating discs can take more abuse than a fixed disc. However, floating discs are heavier and more expensive.

On The Track: A fixed rotor has a more positive feel at the front brake lever and can be grabby at times. A floating rotor is not as positive and can require a little more lever pressure to help stop the machine, but is also more linear feeling.

Oversize Rotors:
This is the most common of all brake purchases. An oversize rotor can dissipate heat more (due to its larger circumference), increase brake pad life, and increase the stopping power to your front brake lever because of its extra leverage. Most stock competition off-road bikes come with a 260mm or 270mm front rotor and a 240mm, 245 and 250mm rear rotor. Aftermarket brake companies usually offer their “oversize” front rotors in either 270mm or 280mm. When going to a larger rotor than stock you will need to also change the caliper carrier, which usually comes with the rotor.

On The Track: A noticeable improvement in braking power. Note that when going to a larger rotor than stock, the brake can become more responsive (or grabby) to the touch of the lever.

Steel Braided Brake Lines:

Steel-braided lines reduce expansion when the brake fluid gets hot. This keeps the lever engagement consistent and in the same spot over a longer period of time. The life span of a steel-braided line is longer than a standard rubber/nylon line that comes on most machines. You get more consistent feel at the lever, and consistency is key for any rider.

On The Track: Just purchasing a steel-braided brake line alone with your stock brakes can increase stopping power, especially in longer races. With a steel-braided line and oversize rotor the braking power becomes more intimidating to less skilled riders, but faster riders usually love how easy it is to get the bike slowed coming into corners.

Brake Calipers:

Another option for Nissin brake riders is installing an aftermarket brake caliper. A couple companies offer different calipers (Ride Engineering and MotoStuff) that can dramatically increase your stopping power. An aftermarket caliper has pistons that are larger than a stock Nissin caliper, and with this comes increased power at the lever. But unlike just going to an oversize rotor, a caliper can give you a more progressive feel. Going to larger pistons changes the leverage ratio when using the stock 11mm master cylinder that most Nissin-equipped bikes come with (Honda, Kawasaki, Suzuki), so it feels more gradual and less grabby. Flex is also reduced and airflow is increased with wider fins.

On The Track: The front brake lever has a slightly softer feel to it with the Ride Engineering caliper, but braking power is increased and is more progressive. Going to an aftermarket caliper gives you a better feel at the lever for increased tire traction when pulling in the front brake or dragging through ruts/corners over a longer throw. Along with a steel-braided line and oversize rotor it becomes easier to consistently ride faster and get into corners. It is also more lever friendly to all types of skill levels.

Brake Levers:

If you’re a picky rider and want to take it even further for that personal touch, there is the ARC adjustable front brake lever. The ARC lever lets you choose from three degrees of lever ratio that will let you dial in where you want the lever to grab. Some riders like a very touchy lever right at the beginning of its pull, and some riders like the lever to grab closer in to the handlebar. With the ARC adjustable front brake lever you are able to dial in your personal setting.

On The Track: This is for the pickiest of riders. If you love to tinker and really dial in your lever engagement placement, this is a great lever. It comes in aluminum and Memlon materials

Brake Fluid:

People often ask if they should use DOT 4 or 5 brake fluid. There is nothing wrong with sticking to DOT 4 brake fluid. Its boiling point is plenty high for any modification that you have read about here. However, do not mix DOT 4 and 5 together. DOT 4 is a glycol-based oil and DOT 5 is silicone based. If mixed, your brake will start to feel mushy and less powerful. DOT 5.1 is glycol based and can be added to DOT 4 if necessary, but it is also wise to flush your brake fluid out completely before adding anything different.

On The Track: No performance difference was felt on the track with DOT 4 or 5 brake fluid, but the lever can feel less spongey when going to fresh fluid.

Brake Pads:

Many companies offer the option of brake pads made with different types of material to alter the response and power of the pads’ feel.

On The Track: After some time riding on rotor-kit-specific brake pads and using stock OEM pads, I say stock pads usually wear more consistently (longer) and have a less grabby feel than most aftermarket pads. Some sintered pads were as powerful as OEM, but nothing proved to be any better than a standard OEM brake pads. We experienced more noise (squeak) on some rotor-kit-specific pads when dragging the brakes, more so than OEM pads. Riders who are known to be brake draggers preferred sintered pads, as heat buildup wasn't quite as bad as OEM pads that were not sintered.

What Do I Think?

All of these mods above will help your stopping power, but it is how you want that stopping power delivered that should guide you on which of these mods you make to your machine. If you feel like you have enough braking power, then by no means do you “need” any of this stuff, but if you would like to stop quicker and maybe be able to dive into a corner harder, one of these mods could be advantage. I normally will not do all of these mods together, as I normally would stick to one or two of these per machine at most.

Akrapovic Evolution Muffler System (2021-2022 Honda CRF450R)

I had the initial impression of the Akrapovic Evolution muffler system as I was doing a MotoConcepts/Bullfrog Spas Honda team test. 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. 

Once out on the track is when I realized that this Akrapovic muffler system could actually help this Honda chassis calm down just like it did to the 2020 chassis. 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 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 only other muffler that I have tried that made a big difference on this bike was the FMF system, but this system really gives you a wider pulling power than the FMF. 

The Evolution muffler is the largest possible muffler for the space available. This allows increased sound silencing, which mitigates the impact on the natural environment while also facilitating improved flow for the exhaust gases to make their way from the combustion chamber with as few restrictions as possible. The added strength created by the design aids durability and provides enhanced resilience in the most demanding conditions. The Akrapovic mufflers have been one of the toughest mufflers that I have encountered over the past couple years when I have tested them! Akrapovic muffler packing usually outlasts others and to me just feels like quality stuff.

The Akrapovic system will save you 2 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 21-22 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 system. 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 along with the Vortex. The combo is an amazing feeling once out on the track! 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. 

FMF Fatty/Gnarly Pipe & Powercore 2 Silencer (2022 YZ250)

The 2022 Yamaha YZ250 is a hell of a fun bike to ride. Even though I am not a huge two stroke guy, I had a great time riding it and thought it had a better engine character than the previous model. The new intake design really helps smooth the power down low and makes it broader through the mid range. There is more rear wheel connection than I remember on the 22, which makes four stroke lovers appreciate this two stroke. I had the chance to try an FMF Factory Fatty pipe as well as a Gnarly pipe with a Powercore 2 silencer and wanted to give you some feedback to see if it could be worth your while on your new 22 Yamaha YZ250.

FMF Factory Pipe/Powercore 2 Silencer:

After installing the FMF Factory Fatty Pipe and Powercore 2 there was some noticeable changes to the YZ’s power character. Bottom end had a cleaner feeling down low as the stock YZ250 does feel slightly rich on low rpm situations. As soon as you crack the throttle you will get a cleaner response, but not any added snap down low. Where you feel the Factory Fatty pipe/Powercore 2 combo is through the mid range as the YZ250 has better pulling power when shifting from second to third out of corners. I also had the feeling that the YZ250 now had a longer pulling top end/over-rev feel and could pull 2nd, 3rd and 4h gears longer down straights than the stock system could. When the track is deeply tilled the FMF system does make the YZ250 feel a little more spunky with its clean mid range rpm response so popping out of corners in a hurry is made easier. I did notice slightly less rear wheel traction with the FMF system, but I don’t think people that are looking to purchase a two stroke pipe and silencer aren’t necessarily looking for rear wheel traction. Overall, the FMF Factory Fatty pipe and Powercore 2 silencer is a nice upgrade from the stock system. Not to mention that it looks really nice with that raw pipe against that blue plastic. 

Gnarly Pipe/Powercore 2 Silencer:

If you’re looking for more bottom end hit, lugability as well as more rear wheel traction the Gnarly pipe/Powercore 2 combo is your ticket. This combo will help with bottom end rpm response and keep that clean feel that the Fatty has, but will get you more snap as well as allow you to lug the YZ250 a little more through corners. If you find yourself a gear too high at times through corners the Gnarly has better recovery than the Fatty does. As weird as it sounds this combo gave the YZ250 more rear wheel traction/feel than the stock system or Fatty/Powercore 2. I can roll the throttle on sooner with this set up and not break the rear wheel loose as easy. Mid range meat/pull is slightly better than stock, but not as good as the fatty. The down side to the Gnarly pip/Powercore 2 silencer is that it made the top end feel rich/dirty so I had to lean the clip (raise one) as well as go down one main jet size. Once I did this it helped clean it up but still didn’t pull as good on top as the Fatty did. 

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

X-Trig ROCS Tech Triple Clamp (2022 YZ450F)

It’s hard to find aftermarket triple clamps that are better than stock these days, especially on the Yamaha YZ250/450. So much is involved in making a triple clamp that flexes enough, but also has enough rigidity to aid the machine in corners as well. With the triple clamp flex character so important to chassis handling (on all motocross bikes) sometimes it’s tough to find anyone that can make a “comfortable” set of aftermarket triple clamps. Why do you need aftermarket triple clamps? Well sometimes it’s just for looks with some riders, but there are occasions where you might want another offset to help you get more stability or a sharper turning character out of your machine. In this case I was looking for the standard offset for a 2022 KTM Yamaha YZ450F and wanted to see if installing X-Trig’s on the Yamaha hurt or helped it. I was hoping to help cornering positivity without sacrificing rigidity balance. Oh and I also purchased these myself for $850.00! 

Enter X-trig’s ROCS Tech Triple Clamps and PHDS Mounts. “ROCS” stands for “Revolutionary Opposing Clamp System”. The ROCS clamp allows for precise alignment of the fork tube with opposing clamping surface patterns, the stiffness of the steering stem is specifically tuned to the respective motorcycle model, the steering-head bearing is already mounted on the shaft tube for convenience, a special fork slot and clamping area for precise fork operation, precise clamping with special screws for low torque specs, OEM attachments can be mounted without auxiliary material, and flexibility that is adapted to the fork with anodizing in the technical factory OEM look. The difference between the ROCS “Tech” and the ROCS “Pro” is the “Tech” uses a standard offset with a pressed shaft tube. The “Pro” has two offsets you can choose from by simply adjusting the shaft tube (or steering stem). I didn't feel like the Yamaha needed an offset change as the Yamaha is predictable on straight line and corners well, so I stuck with the “Tech” clamps. 

The PHDS (Progressive Handlebar Dampening System) is a system supported by elastomers designed to absorb engine and chassis vibrations. The system also dampens the forces acting on the handlebar in a horizontal and vertical direction, maintaining steering precision. The handlebar can be adjusted in 12 different positions when the PHDS is mounted. The Yamaha doesn’t necessarily vibrate more in the handlebar area than any other 450 motocross bike, so this isn’t something I feel the Yamaha needs particularly, but if it helps, so be it.
Installation of the ROCS clamp is fairly straight forward (with the pressed shaft tube). All you need to do is grease up the steering head bearing and slide the bottom clamp up in the head tube of the frame. Super clean! Mounting up the PHDS bar mounts is a little tricky as the mounts themselves have a lot of moving parts, so make sure to read the instructions to ensure proper mounting. Technical Touch offers optional PHDS bar mount elastomers that come in soft or firm, but I chose to run the stock medium style elastomers, which seem to be just fine for motocross conditions. 

I am super picky about bar positioning, shocking I know and the Yamaha isn't the best rider triangle out there, so I went with the second mounting hole closest to me (when sitting on bike) on the triple clamp with the PHDS mounts back. This handlebar position gave me a +3mm bar position (forward from stock), which I preferred as the stock positioning is a little cramped for my 6’0 frame. The PHDS bar mount itself is +2mm higher than the stock bar mount, which I was just fine with as I am using a SX Race Pro Taper EVO handlebar on the 2022 YZ450F. Having so many positions available for the rider is definitely a huge positive for adjustability with these ROCS clamps on the Yamaha to open up the cockpit for you bigger riders (5’11 and up). If you feel like you need a higher PHDS handlebar mount, X-trig also offers spacers to go under the PHDS mounting system. You can pick from 3mm, 5mm, and 10mm spacers.

So what did the X-trig ROCS Tech Triple Clamp and PHDS handlebar mounts do on the track? My goal for this test was to dissect the anti-vibration qualities as that seems to be the easiest to feel asap. I honestly didn’t notice any less vibration/harmonics through my Pro Taper’s, but I did notice slightly less vibration on higher RPM’s which I found strange. The PHDS mounts do help flex and are a little kinder to my wrists than the stock mounts. While I was looking to get a more precise front end feel through corners, without getting added rigidity on hard pack/rough straights, that is not quite what I found. Basically I got slightly less compliance on lean angle bump absorption so the front tire didn’t exactly feel like it was digging into the dirt enough for me on faster sweepers with chop. The X-Trig ROCS Tech clamp on the Yamaha YZ450F provided enough flex if I was heading straight into bumps, but once I started leaning into braking bumps to set up for the corner, there was definitely less comfort in that area compared to stock. There was some added rigidity when leaning when bumpy and that cause the fork to feel harsher. The ROCS Tech clamp is most noticeable in a positive way when diving deep into a rut where there is a huge load put on the front end, forced by the rider. The chassis positivity through this area is much better than the stock clamps. The stock clamps has a tendency to flex too much and give the rider a wiggle once off throttle in area 1-2 of corners, (on deeply tilled tracks or soft dirt) or give the rider an unsettled (dive) when dropping into a long/deep rut (this sensation can only be felt mostly by faster or heavier riders). The X-trig ROCS Tech clamp gives the front end less wallow (firmer) and more cornering stability once inside the rut (without upsetting chassis balance). Straight line stability isn’t as good as stock as you do feel more of the track under you (front end) on hard pack west coast conditions.

I do feel like slap down landing of the PHDS mounts are more absorbing and I like that feel to my wrists. I am almost keen to try these mounts on the stock clamp to see if that works as good on my old ass wrists! The overall weight of the X-Trig clamp and PHDS mounts are heavier than stock so know that you will be gaining almost a pound of front end weight on your machine. So at the end of the day am i happy with my purchase? I would say for this bike, no I am not. I will say that I have tried X-Trig’s on a KTM with really positive results, but this confirms to me that the average rider DOES NOT need these for his Yamaha YZ450F. Does that mean all aftermarket clamps are rated under the same umbrella? Absolutely not! Not every clamp is created equal. I will try some more aftermarket clamps on this machine in the coming weeks to see if we can keep the stock bump absorption while adding to that positive front tire feel in ruts. Stay tuned! 

Akrapovic Evolution System (2021-2022 KTM 250 SX-F)

When you purchase a 2021 KTM 250 SX-F TLD version the bike comes with a slip on Akrapovic Evolution muffler. However, I know that sometimes, certain machines react better to full systems rather than slip ons, we decided to get the full Evolution system to see how it changes the KTM 250 SX-F’s engine character. 

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 TLD version 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, but the muffler pitch is so quiet that 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 or stock muffler 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 250 SX-F 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. The full system just simply gives me more “meat” in the mid range.
 Top end and over-rev is where this Akrapovic Evolution system shines. Adding top end and over-rev to the already very capable KTM 250 SX-F 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 I swapped to an aftermarket ECU. 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. 

As described the Akrapovic badging will eventually get marked off when cleaned.

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. 

A couple of durability notes: 

-The Akrapovic lettering on the headpiece resonance chamber will wear off after a few washes. 

-The Akrapovic muffler stickers will burn away around the 7 hour mark. 

-The overall quality of the system and the parts inside the muffler are second to none. The muffler packing lasts longer than other aftermarket systems and the hardware it comes with is superb. 

-Is the system worth the $1200.00 price tag? Comparing it to other systems out there, I would say you’re getting what you’re paying for. A lighter, race oriented system that gives the rider better overall power throughout the rpm range. 

Raptor Titanium Offset Footpegs (Yamaha YZ250F/450F)

If you’re a Yamaha guy, chances are you may be looking to get your cockpit a little more roomy right? The Yamaha YZ450/250F needs a better rider triangle in stock form so I scoured the internet to see if I could find a way to improve it. A lot of factory motocross teams run Raptor Footpegs and up until recently I didn’t even know they made custom offset pegs for current motocross machines. I discovered that Raptor Titanium makes two separate custom offset pegs that are 10mm back as well as 7mm down and weigh in at 300 grams per set. I ordered up both to see if it could help my cockpit woes.

Raptor Titanium is located in the UK and make these custom offset pegs to order, so there is some lead time on each order. I ordered my two sets and got them in approximately 25 days, which I was just fine with. Raptor pegs are developed in collaboration with OEM manufacturers and factory motocross/supercross teams, offer superior strength, crafted by British engineers using hand-fabricated, aerospace-grade 6Al-4V titanium and the latest manufacturing techniques to produce some of the most cleanest welds I have seen, they are CNC-machined back-end for precision fit, are ultra light-weight at only 300g per set (including springs), have razor-sharp teeth, a wider 24-tooth platform offering a greater surface area and come with a set of stainless springs. 

The Raptor pegs are works of art and are very light when holding them compared to the stock pegs. Installation was fairly painless, but you will notice that the Raptor pegs will slightly have an upward bend to them unlike the stock pegs which sit fairly flat. I thought the slightly upward bend would bother me, but it actually keeps the ends of the pegs from dragging up faces of jumps or from digging into the ruts as much as the stock pegs (even with the different offsets). I decided on the RX003 design which has a middle bar/cleat (with teeth), but Raptor does have a peg that offers an open cleat design which really deters mud from packing in if you prefer that route. The teeth are super sharp and offer a superb standing platform and make it easier to feel more confident when standing on the balls of your feet. Sometimes with stock pegs, the teeth aren’t sharp enough for you to ride on your toes and you will slip off the peg easier. The Raptor pegs invite you to ride on your toes/balls of your feet more and offer you the security to get into the right foot position. Below are the two offsets that I tried from Raptor Titanium and how I felt about each position on a 2021 YZ450F. 

10mm Back: 

I tried this position first and quite honestly was surprised that I didn’t like it more. The position of the peg put my knees in an awkward position when I was braking which upset my technique. I also felt that by putting the pegs 10mm back, it made shifting and braking a little more difficult to get to for my size 10 feet. I am 6’0 and I personally think going 5mm back would be a better fit for me and my stature. I do like the position when seated going through corners as it prevents my knees from getting too close to the handlebars or from smacking them with my knees. 

7mm Down:

This is was my favorite setting as it helped the cramped seated position of the stock pegs and allowed me to move around on the bike more freely because it allowed me to stand up easier without having to get too crouched. I also like that it didn't affect me when I scrubbed a jump or went through deep ruts. The 7mm down position still gave me enough ground clearance for both. Having the pegs 7mm down also gave me a more relaxed feel with the Pro Taper SX Race bar bend that I have on my bike and makes the dip in the stock seat not as apparent. If you’re 6’0 or over, I feel like a tall seat along with the 7mm down pegs could really change the way you feel on the Yamaha for the better. 

Overall:

Yes, these are pricey, but if you’re looking for a more comfy feeling out of your Yamaha then going with one of these Raptor Peg options are a god send! There are only a couple companies that make offset pegs for the Yamaha, but the Raptor pegs seem to have the most quality out of the bunch. If it was any other bike than the Yamaha, I wouldn’t spend $300.00 American dollars for a set of footpads, but the Yamaha really needs this mod to help my tall lanky ass feel more comfortable when I am riding. To me it’s spendy buy, but necessary if you’re needing some cockpit help. Head over to www.raptortitanium.com to see more and place an order.

Since these are pricey, if you have any questions, please feel free to email me at kris@keeferinctesting.com

Acerbis K-Future Handguards

I have gone through a few hand guards over the years and have had my favorites, but recently we got to try the Acerbis K-Future Handguards for our KTM 250 SX-F test bike. The Acerbis K-Future Handguards have dual-injection covering, a lightweight, compact yet flexible flap design that can protect your brake/clutch pumps. I like that you can directly fix the K-Future Handguards to Brembo/Magura clutch/brake systems with just a bolt that is provided by Acerbis. You simply take out your OEM clutch/brake perch bolt, install the Acerbis hardware, one zip tie and boom! DONE! These guards are not a pain in the ass to install and it’s even more awesome that I can replace the stock crappy KTM XC guards with these quickly if need be.  

Acerbis offers a wide range of guards on their site, but we were looking for some handguards that could withstand some light smacking of some bushes (west coast bushes like greasewoods, manzanita, cholla) in the desert as well as deflect some roost/rocks on the motocross tracks. I like that the K-Future guards can pivot along with your clutch/brake adjustments and follows the angle in which you put them. The angle in which the guard is placed in conjunction with the lever seem to be just the right level with a couple test riders that rode with these guards. If you like to have your hand guards offset from your levers then these guards may not be the right choice for you. I would make look into the X-Force hand guards for offsetting your levers in order to get the right amount of courage for your hands. In our case the K-Future guards protected our paws flawlessly with her issues. 

The amount of coverage the K-Future hand guards provide is something I should have looked into a while ago. Although I am not a huge handguard guy, I recently broke my pinky finger and could have used them in a race at Glen Helen. Visually hand guards bother me when riding, but with these K-Future guards, I didn’t really get bothered by the wide look of them. The way the guards are shaped gives my eyes a less wide/fat feel on the bike. Ventilation has been excellent on hot summer days. There hasn’t been one complaint of hot hands during our long summer motos here in Southern California. The vents are not so big that dirt or roost can hurt the hands and I also like that I can hit a right hand inside corner hard enough and not snag my front brake on a stake or hay bale. Yes, we still have hay bales here on occasion! When we did venture out into the desert for some trail rides, we did like that the K-Future guards were sturdy enough to smack some bushes (not trees) at speed without wincing in pain because your hand just took a 60mph impact.

For $52.95 the K-Future handguards are a good investment to help prevent rocks and roost from hurting your fingers/hands. As I am typing this now, my pinky is still pissed off at me because I didn’t have these on. Three months later and it still hurts! I must be getting old because I am wearing a chest protector and handguards! Holy crap, send help!

Dubya Edge Wheel Set

I will be straight up with you all… I am not a huge fan of $1500.00 wheel sets. Most of the time, I am a big stock wheel/hub guy, but in some cases I do need a little more security or toughness  in my wheels. I am a big believer of bringing an extra set of wheels to the track just in case you get a flat or have some sort of wheel failure. Full disclosure: The Dubya Edge Wheel set has been in my shop for more than a year and I am just now getting the information out to you guys now! Why? A couple reasons… I am normally a stock wheel set kind of rider and I am very finicky with rigidity, yet most of the time aftermarket wheel sets have given more rigidity that I wasn’t looking for. Finally, after a year or so, I got off my ass and put them on my 2021 Honda CRF450R as I have experienced some wheel problems with my Honda’s in the past. So why not test the Edge wheel set with a bike that actually could use it! 

The Dubya Edge wheel set was created for the blue collar type of rider that is looking for some added bling with durability. Each Edge wheel set centers around a forged aluminum Edge proprietary hub, which are laced to a Dubya by Excel rim, using stainless steel Dubya spokes and nickel plated steel nipples. Each wheel set is pre-assembled in Dubya USA’s Southern California facility by the same technicians who assemble all of Dubya’s top professional factory riders and teams wheel sets. Instead of using your stock wheel spacers, the Edge wheels come with their own specific spacers to each bike. I actually like when aftermarket wheels come with their own spacers as it can make your dollar stretch further! How? Well, we have a couple Yamahas in the shop that have different axle sizes (two and four stroke) so it’s nice all we need to do is swap spacers instead of getting another hub. It just makes swapping wheels more seamless. 

We have put nearly 50 hours on the wheels themselves and so far we have been pleased. The hub has been surprisingly not as rigid as I initially thought and the rim also has held up to the standard local motocross abuse. I am not over jumping landings or slamming into faces of jumps on purpose, but I feel like I am fairly hard on a bike, yet these Dubya wheels have given me zero headaches. The stainless spokes needed to be adjusted a few times after break in, but since then, they have stayed within a quarter turn of true. For $639.00 I feel like this wheel set is a great purchase for the rider who wants a fresh look on his/her bike as well as some durability that you maybe can’t find at times from your stock wheel set. I also like that the color of the hub doesn’t fade or beed out after several rides/washes. I don’t trust a lot of “inexpensive” wheel sets, but this is one that I am happy to put my hard earned money on. The weight of the complete wheel set is just north of the stock wheel set by a half a pound, but this is something that I did not feel once out on the track. 

The Dubya USA Edge wheels are available with the standard front rim size 21×1.60, while the rear wheels come in 19×1.85, 19×2.15 or 18×2.15 rim sizes. If you’re looking for some cool colors, the rims come in either black or silver, and the hub color matches the brand of machine you’re riding. The only brands that can mix and match the Dubya USA Edge hub colors are KTM (orange) and Husqvarna (blue), since they are exactly the same, but I don’t think you will be running blue on your KTM. Dubya currently doesn’t offer an Edge set up for the #RMaRMy, but hopefully you Suzuki lovers can do your battlecry loud enough, so that John and Kristen from Dubya can hear you.   

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

FMF 4.1 Muffler System (2021 KTM 250 SX-F)

My son and I have been going back and forth on mufflers for his KTM 250 SX-F and have went though about three until we settled on the FMF 4.1. We have tried the HGS (which was good), a Yoshimura, as well as a Pro Circuit system, but for his riding style and what he was looking for from the engine character, we decided on the FMF 4.1 system. Why? Here are some reasons why the FMF 4.1 system works well for Aden and the KTM 250 SX-F. 

First off, the FMF 4.1 system looks beautiful and is easy as pie to put on. Installation literally took 10 minutes and I like that FMF pipe springs last longer than the stock KTM pieces. Aden rides lower in the rpm and only revs his bike in the air (which he thinks helps him but it really doesn’t) so he needs some low end rpm response as well as some low end torque to help get the KTM back into the meat of the power (or “recovery”). You will get more low to mid RPM response as well as more mid range pulling power with the 4.1. Top end is increased slightly plus the over-rev is as good as stock. It is one of the few times that I was impressed with a muffler because it was actually better than stock in almost all areas. THIS IS VERY RARE! Coming out of corners the KTM 250 SX-F now has some more excitement in second gear and pulls harder than the stock system. Third gear roll on is also noticeably more reactive to your throttle hand (increased connection) and can allow for a lazier rider to have more pull in softer loam. We did pull the spark arrestor/insert out with good results and decided to leave it out for maximum throttle response and torque feel. Leaving it in will kill a little low to mid response, yet you still will get better torque feel over stock. 

The downside is that you must keep up on your muffler packing (every 10-12 engine hours) because the FMF will blow out and that could damage your expensive titanium can. Just in case you’re numbers guy, did I mention that you will lose almost two pounds with the titanium 4.1 system? If you slap on spring forks on your KTM, you will be gaining almost three pounds. You can get most of that weight gain with the spring fork back down with a 4.1 Titanium FMF Muffler system.

Things to look out for? I can burn a lot of pants on the headpipe of the FMF system. The magabomb portion of the headpipe can burn your pant just above the boot when sticking your leg out in deep ruts. This has happened on only a couple different brands of gear (FXR, FLY) with the FMF headpipe installed. Overall we are happy with this system for the way Aden likes to ride and will be refurbishing his mufflers every 10-12 hours in order to keep the most performance possible. Hopefully FMF will have these back in stock in the near future so be on the lookout over on their website that gets updated weekly on what is in stock. Damn you Covid!

REC Seat Nuts (Kawasaki KX 450/250)

The REC MX Seat Nuts are designed to be an OEM replacement and use the OEM bolts. Chances are if you have a Kawasaki you already have stripped out the threads on the OEM nuts as they are just too soft. The REC Seat Nuts take a little work to fit/press into the rear fender, but once inside the chances of you stripping out or losing them like the stock nuts are slim. The nuts are $29.95 a pair (kind of expensive), but have eased our mind about possibly losing a seat on the track. No one wants to ride back on the track to find their seat and take that ride of shame through the pits. Grab your balls and get some seat nuts! You can go to RECMX.com and check them out.

Slip On Or Full Muffler System (2021 Honda CRF450/250R)

Some muffler questions that get sent to my email inbox usually look like, “which muffler is best for my bike? “Is a full system worth the money or can I just get away with purchasing a slip on”? “Is my stock muffler the best muffler option for me”? Instead of trying to keep answering some of these emails, I thought I would write an article on some of the current 2021 motocross machines and which mufflers do what to the power curve as well as if they are better than stock. Now I haven’t tried every aftermarket muffler out there, but if you’re in the market for one and need to decide on if your bike works best with slip on or full system, you have come to the right place. I have also put together a sidebar on if the stock muffler is worth a crap or maybe you should just save your money because the OEM muffler is a good stock system. Just because it is “stock” doesn’t mean it hasn’t been fully developed by the manufactures. Not all stock mufflers are created equal, so read below and see if you need to keep your stock muffler on your Honda CRF250/450R, get a slip on, or maybe go all out and purchase a full aftermarket muffler system. 

Honda CRF450R: 

Full Muffler Systems Tested: Yoshimura RS-12, FMF 4.1 RCT, Pro Circuit Ti-6.

Yosh Summary: Smoother roll on/less RPM response than stock muffler which makes it slightly easier to control down low. Mid range pulls longer than stock and top end over-rev is as good as stock. 

FMF Summary: Better roll on delivery with a snappier throttle response which can help let the CRF450R roll third gear more through corners. You would think this might be contradictory to what you want out of this machine but this allows to run a higher gear which calms the chassis down. Mid range has a smooth/meaty pull but signs off earlier on top end than the stock system. 

PC Summary: Long linear power character with no real explosive snap down low like the stock system. The PC system calms the Honda’s chassis down under acceleration and adds more mid range, with slightly more top end pulling power. Over-rev is as good as stock. 

Slip Ons Tested: Yoshimura RS-12, FMF 4.1 RCT 

Yosh Summary: Retains more of that smoother roll on power, similar to the full system and keeps the longer than stock mid range power, but to me the rpm response suffered a little on low to mid range areas of the track. I wanted just a little more of that stock muffler excitement in these areas. 

FMF Summary: Throttle response isn’t as good as full FMF system and the Honda will not pull third gear as good out of corners with slip on, but 

Stock Muffler Character: Strong low end pulling power (sometimes too much when rolling corners) with touchy low end rpm response. Broad mid range power with a long top end pulling power. 

Slip On Or Full System?`: The stock muffler is just to touchy down low and that can lead to a lot of mistakes when trying to roll your corners or when you get tired. To me an aftermarket slip on, not a full system is the most bang for the buck on the CRF450R. I prefer the FMF slip on because if it has a snappier rpm response yet a smoother roll on mid range character than stock and this seemed to help the Honda’s chassis the most. The Yosh is also a great choice but maybe slightly too lethargic for my taste on low to mid range rpm response, but I do think t his is a great choice if you’re looking to lighten up your machine as well as tame it down some.  

Honda CRF250R: 

Full Muffler Systems Tested: Yoshimura RS-9, FMF 4.1 RCT, Pro Circuit Ti-6 

Yosh Summary: Less bottom end than stock but more mid range pulling power and top end. Low and mid range rpm response is same as stock with slightly crisper FI feel than stock muffler. 

FMF Summary: More bottom end than stock muffler with increased mid range pulling power, but with less top end pull than stock muffler. Low end rpm response has more snap but muffler is considerably louder than stock. 

PC Summary: Better low end rpm response than stock but with a smoother pulling power out of corners. Mid range pull is longer and allows rider to get into third gear sooner than stock without abusing clutch. 

Slip Ons Tested: Yoshimura RS-9

Yosh Summary: Better low end feeling out of corners than the full Yosh system, but still not as much bottom end than the stock system. Mid range pulling power feels as good as full system but with less top end/over-rev. 

Stock Muffler Character: Smooth roll on delivery with crisp low to mid rpm response. This machine could use more low to mid range torque feel in order to get rider out of soft low speed areas of the track better. 

Slip On Or Full System?: The CRF250R needs more bottom to mid range pull so I have found going to a full system benefits this machine the most. The FMF or PC both have unique characters that I need in order to shift sooner and pull out of corners with more authority. The FMF is a louder muffler system than the PC so if louder mufflers are not your thing you might want to go to the PC system for a deeper/less raspy sound. If you put inserts into the mufflers of the FMF, it kills some of its best benefits (less rpm response/low end feel).  

Frame Tape Review

I have never really had the best of luck with frame tape in the past. Although frame tape works really well, they typically only last one day at the track. I was determined to find something that was better than one ride, so I went searching the internet and ordered up a few different types of grip tape. Instead of writing you up some big article about which tape sucked, I decided to write an article about a gentlemen’s frame tape that I found was good enough, that I would spend my own money on it. I will say it was kind of random because I stumbled upon Corie through Instagram where he suggested I try his tape. After I got Corie’s product and rode with it is when I ended up finding out that he supplies A LOT of other top teams in Supercross frame tape for their machines as well. Corie Barbee doesn’t do this as his job, it’s basically his hobby after he gets off work at his construction job. 

Now that you know a little background about the person behind the product, what is this tape all about? Corie doesn’t use anything magical as his product is a 3M tape that anyone can order online, but it’s the template that makes the biggest difference. The cut is where the magic is and if you end up cutting your own (which I have tried) you have to make sure there are no grab spots or sharp corners that can cause the tape to lift. It’s not actually as simple as it may seem! I don’t have the patience nor the time to do this so I would rather pay someone to cut them out for me. Corie’s cuts were spot on and the two different types of frame tape that I used (on a Honda CRF450R, YZ450F, and KTM 250 SX-F) lasted three to four full days of riding yet when peeled off by hand, it was the cleanest out of all the brands of tape I have tried.

As you can see here in this photo, I needed to clean my frame better in order for the tabs to stick.

The gray frame tape is a 3M rubber base that blends/grips well with your boots. The amount of grip I had when squeezing each machine made me feel more like I had more contact which gave my arms more of a rest during motos. 

The black frame tape is a more aggressive style of tape that has a thin foil backing between the grip and the glue, which worked out well for the KTM’s steel frame. This tape bended around the frame tubing more accurately than the gray tape and gave me a more secure lock in feel than the stock frame guards that the KTM comes with. The only other frame guard that is better than this black tape is the Acerbis frame guards. 

In order to get Corie’s frame tape to stick proper you have to make sure to prep your frame properly with contact cleaner. Make sure there is no sticky residue on the frame and that you evenly press down on the complete surface area of the tape. The frame tape aren’t meant to last forever so don’t expect it to last a month of riding. For frame tape to last as long as this tape has is saying something, trust me. All of Corie’s templates are hand made/drawn and he hand cuts every piece of tape individually. If you want to hit up Corie for some of his tape, email him at coriebarbee31@aol.com or 334-312-6138 to order yours. Typically a set of frame tape will set you back $15.00-$35.00. If you’re looking for more grip in between your legs, try Corie’s tape, it’s pretty damn good!  

Akrapovic Evolution Muffler (2021 Yamaha YZ450F)

The Akrapovic Evolution muffler system is one of the most beautiful looking systems out there in the market today, is well built, and has quality welds all the way around it. Once hot, the titanium color of the headpipe is the most dynamic blue you will ever see from any muffler manufacturer, which just makes you feel that much more factory on the starting line right? The Akrapovic Evolution titanium muffler system is 1.5 pounds lighter than the stock YZ450F system and tucks under the right side panel much cleaner than other systems that are on the market. When putting on the system, make sure to leave the headpipe loose and then connect the mid pipe, so that the slip fit joint slides in easily. Once those two pieces are connected, tighten the headpipe bolts and mid pipe bolt just snug. The Akrapovic uses your existing stock heat shields or you can purchase carbon heat shields separately. The Evolution muffler uses an aluminum spacer in the rear hole to give the muffler enough clearance (from the brake caliper) once the suspension is fully collapsed. This system is one of the easiest to install and I have been putting a ton of systems on this blue bike lately. I did notice that there is a small screen deep inside the core of the muffler, however I was told that this isn't a spark arrestor, but a noise insert. Note: Leave the insert in, as the muffler performs better with insert in and is much pleasant to the ear. Once rear section (muffler) was installed, I went around and tightened up the remaining bolts. Doing it this way ensures there is absolutely no binding going on between each slip fit joint. 

Out on the track the Akrapovic Evolution muffler has a deeper sound and is much quieter than the stock system. I started the test with the “TP 3.0 and stock” maps installed inside the 2021 YZ450F (if you don’t know what the TP 3.0 map is, email me at kris@keeferinctesting.com). Roll on power delivery was smoother than stock out of corners (with either map) with the Akrapovic, compared to the stock system. I have grown to love the smoother roll on power that the Evolution system delivers as it really helps me roll my corners better without getting the chassis upset. The connectivity of the Akrapovic muffler is second to none as you will notice more rear wheel connection under heavy throttle. 

The Akrapovic system really comes to life once out of corners as the Yamaha now starts pulling harder and longer than the stock system down straights. Second and third gears can be stretched longer by the rider with the Evolution system and rolling third gear in corners is slightly easier on the rider as well (with stock gearing). Over-rev is better through each gear with the Akrapovic and the overall engine feels like it revs a little quicker/freer. The freer feel takes away some engine braking sensation on de-cel and also helps the Yamaha handle slightly better coming into corners. Yes! All from a muffler! 

In conclusion, I feel the Akrapovic Evolution muffler system is an excellent system once you can dial in your favorite desired Yamaha Power Tuner App setting. You will not be getting more bottom end than a stock system, but the gains through the mid-top end are a noticeable difference. It will be up to you if that difference is worth the $1300.00 you will spend on the Evolution titanium system. Akrapovic’s website is a very informative, clean, and one of the best aftermarket muffler websites to browse around on if you have the time. There are dyno charts, a sound tool that lets you compare the stock system to Akrapovic’s muffler pitch, documents of replaceable parts, and technical data about the system itself. You can head over to akrapovic.com and punch in what bike you want to geek out on. I did, for a while!

Extra Credit: If you’re like me and still want more power yet even more connectivity, look at getting a Vortex ECU mapped by Chad at XPR Motorsports for this 2021 YZ450F. You might think that putting a Vortex on a YZ450F is over kill but what you're getting is a faster, yet easier to ride Yamaha that will allow you to ride it harder. Less on/off feel with this muffler system and the Vortex ECU. I have created a couple maps with Chad on this Vortex and along with this system has made this machine easier to ride. I have let other R&D test riders ride my test bike with these two mods on and they were blown away.

Email me if you have any questions or concerns about this test kris@keeferinctesting.com. 

Dunlop MX12 Rear Tire (120/80-19)

Dunlop offers a wide variety of tires for us moto/off-road guys but you don’t see too many reviews of the MX12 scoop tire out there. I recently had the chance to try a 120/80-19 rear MX12 at a few different tracks that range from sand to intermediate terrain with the occasional hard pack afternoons at Glen Helen. The Dunlop Geomax MX12 rear tire is a soft-terrain tire designed specifically for sand and mud conditions. The Geomax MX12 is the replacement for the MX11 that was out a few years ago. The Geomax MX12 rear tire was made to try and improve performance in mud, sand and soft dirt while expanding the range of conditions it can be used compared to the older MX11 design. Dunlop designed the MX12 to have increased rear wheel acceleration traction, lean angle grip, improved control in ruts and enhanced bump absorption when coming into corners. 

Fresh Dunlop MX12

With Dunlop’s V-block tread pattern and over 1.5 inches between each row of knobs, the MX12 is can scoop dirt and help move the motorcycle forward in places where a standard MX33 tire would need more help. Additionally, the V-block pattern helps fling mud off of the tire and cleans it off in wet conditions. Dunlop’s block-in-a-block progressive cornering knob technology, used on the MX33 and MX53 tires, has been implemented on the MX12 as well to help cornering traction and slide control. Ribs have been added to the backside of the knobs to improve stability in braking and choppy rutted out corners. No matter how much traction you get out of a tire, it will never be good without consistency. Without these ribs, the steep knobs could bend and fold over, which you don’t want when trying to get on the throttle hard (while leaning) out of a corner. In the testing world, we call this “cornering stability”.

I have ridden with a Dunlop MX12 on 250 and 350’s before but this was the first time I have experienced it on a 450. It’s seriously like cheating when coming out of softer corners. Getting on the throttle harder is made easier as the motorcycle accelerates harder with less throttle. This also makes abusing the clutch much less and allows the rider to use less energy around the track. Another notable positive for me was being able to use alternate softer lines that were too deep for previously used soft to intermediate tires. Instead of sinking into soft soil, the MX12 tire stayed on top of the dirt much better than other soft-intermediate tires. When compared to the Dunlop MX11, the MX12 is easier to lean into a corner and maintain that lean in a choppy rut. Cornering stability has improved on the MX12 (compared to the MX11) and it’s also easier to keep that lean in a rut that is choppy and hacked up.

Dunlop MX12 With 6 Engine Hours Of Soft To Intermediate Terrain Time

The portion of the test where I was most impressed though was how the MX12 reacted to harder conditions. On intermediate to hard terrain, the MX12 dug into the dirt and hooked up surprisingly well. With the added stability from the reinforcing ribs and the staggered knob pattern, the MX12 felt better than some other intermediate to hard terrain tires I have ran lately. The downside to the MX12 was that on hard pack flat corners it doesn’t have the best lean angle grip. It will slide around more than I would like, but that is to be expected on hard pack with a scoop. However, if there was only a couple parts of the track that had hard pack corners (and the rest of the track was softer), I would gladly take this MX12 because that is how good it works on the other parts of the track. The durability of the MX12 is great if used on strictly soft terrain, but if used on intermediate terrain it can break down the carcass of the tire much quicker. The knobs will not chunk as quick as the carcass will break down. The ribs in-between the knobs will break down over time faster on hard pack. A starting point that I liked for air pressure was anywhere between 12-12.5 PSI.

Dunlop MX12 With 8.6 Engine Hours Of Soft To Intermediate Terrain Time

If you are looking to get great starts on softer conditions and hook up out of corners like you never have before, look at the MX12 scoop tire. This tire has changed my way of thinking when it comes to what I am going to be running on race day. I wouldn’t even mind running it on late afternoon motos at Glen Helen. Just because of the scoop design, don’t disregard this tire when the conditions go from soft to intermediate. This MX12 rear tire still hooks up well! You can find the MX12 over on rockymountainatvmc.com for $93.00.

Ride Engineering 23.5mm Offset Split Triple Clamps (2021 Honda CRF450R)

I have been looking for some added stability and comfort from my 2021 Honda CRF450R test machine since I got it and although my suspension setting has evolved/improved over time, I still need some compliancy from this machine. I have been working with Adrian over at Ride Engineering on some split triple clamps for over a year now and we finally have come up with a feel that I think is better than stock. I have yet to test any other competitors clamps back to back as Ride Engineering is one of only a couple aftermarket companies that are making different offset clamps. I have tried a 24mm offset on the 2020 Honda CRF450R and really liked how it made the Honda have a “slower” feeling chassis. Slower in this sense was a good thing for the Honda as it calmed the chassis down on rough tracks for me. So in order to get some added chassis compliance, I tested Ride Engineering’s 23.5 offset clamp for the new generation Honda CRF450R and here is what I took away from the test. 

Stats:

The Ride Eng. 2021 CRF450R/RX Split Triple clamps are available in Red or Black, come in two offsets and cost $649.90. Custom colors available for $100 additional if you want a custom set. The Ride clamps save you 10oz. in weight and come in 22mm offset or the new 23.5mm option. A Showa steering damper option is available without drilling your frame so no need to stress on that. The bar position on 22mm offset is 8mm forward of stem hole allowing a 5mm or 11mm bar position, with Ride Engineering’s one piece bar mount ($104.95), also available in 7/8” version. The bar position on 23.5mm is 9.5mm forward of stem hole allowing a 6.5mm or 12.5mm bar position with Ride Eng.’s one piece bar mount (I preferred mine set at 12.5mm). Note: Stock OEM bar mounts will fit and affect the numbers above by 2mm (3mm or 13mm on 22s & 4.5mm & 14.5mm on 23.5s).   

How Do The Ride Engineering 23.5’s Affect The 2021 Honda CRF450R?: 

I will be quite honest with you… We went through a couple of versions before I felt that it was good enough to sell to the public. The first couple versions didn’t have the compliancy I needed nor did we have a different offset yet that I preferred. The first thing that I noticed with the Ride Engineering 23.5mm offset clamps is that it took away some of the dreaded vibration that the 2021 CRF450R has through the bars. Once I pulled out onto the track and started to accelerate I could feel less harmonics/vibration coming through the Pro Taper bars. What I wanted from the 2021 Honda CRF450R (as well as from the Ride clamps) was a calmer entrance in/through corners, less oversteer, better straight line stability, and increase in front tire tracking. 

I got all of this with the new 23.5 Ride Engineering setting! With my fork set at 2-3mm in the clamps as well as a rear shock sag measurement of 105mm I had a CRF450R that was less harsh feeling through my hands. Now the Honda didn’t quite give that sting through my arms on flat landings and gave the front end an increased flex feeling. Diving into ruts that start to get hooked, didn’t give me the front end knifing (oversteer) that I experienced at times with a 22mm offset. We call this cornering stability in the testing world and the new 23.5mm setting gave me increased cornering stability. Let’s face it, we all love the way the Honda corners, but sometimes it can corner too good and cause some in consistencies in your cornering technique. This 23.5mm offset Ride clamp still gives you that easy to lean front steering feel of the Honda, but improves area 2-3 (mid-exit) in corners.
Straight line comfort has also been improved thanks to losing some rigidity up near the head tube area. When testing the Honda CRF450R I never could have suspected that the OEM clamp was some of the problem when it came to getting a harsh feeling. Hitting square edge and braking bumps with the 23.5 Ride clamps gave me less harshness and improved my fork feel. The fork now seemed to move more in the stroke and had a slightly softer feel to it, which was nice, but also forced me to adjust my fork setting somewhat. With the Ride 23.5 clamps, I had to stiffen up my fork setting one click and slow the fork don one click also. Doing this gave me a better front tire feel when leaning on throttle. I ended up getting better front tire tracking (when stiffening/slowing the fork) when cutting across rough sections of the track. Once I figured that I could go stiffer with my setting it actually brought up the performance/comfort feel of the Honda CRF450R. The stock torque specs of 15 ft. lbs. on the top clamp and 12 ft. lbs. on the bottom clamp is recommended, but if you end up purchasing a raw/silver clamp, you can go to a 14/11 setting. 

So what’s the negatives? Honestly for a vet rider like myself, there aren’t too many… I do know that this isn’t a cure all for the rigidity issues of the CRF450R, but it does help a noticeable amount. When I let another Honda rider/owner try my test bike with the clamp, he immediately thought his OEM clamp was too stiff feeling. The negative for me is that you may have to adjust your suspension (to compensate for the softer feeling clamp) a little after installation, but to me having to do some minor clicker adjustments isn’t too much to ask for added comfort. Plus, y’all are Honda owners. You’re used to tinkering on your bikes right? I know I am when I ride this machine. This Ride Engineering 23.5mm offset split clamp will eliminate some of the tinkering you’re doing at the tracks most days by 40%, so you can ride more and be a test rider less. 

If you do end up getting the red colorway, please try to cover your clamps up with a towel or something when your bike is siting in the pits. The sun will fade the anodizing over time, so bring an EZ-UP or a towel to cover up your investment. These clamps are sexy looking so take care of them! If you’re a C rider worried about if you will lose that cornering ability of your Honda, have no fear, adding these clamps to your machine will not negatively affect how easy the Honda will lay over in corners. In fact, it might help you improve your corners as the CRF450R will setting into the corners better with this 23.5 offset. 

There is a discount code available if you decide that this may be something you're interested in. KT20 will save you 20% off your order over at ride-engineering.com. If you have any questions or concerns  about this test please feel free to email me at kris@keeferinctesting.com.   

Yoshimura RS-12 Stainless Muffler System (2021 Kawasaki KX450)

The stock 2021 Kawasaki KX450 is pretty damn good machine, but that muffler looks atrocious right? We called up on Yoshimura to see if we can get a more attractive aftermarket muffler system that is actually better than the stock system. I will say that the stock KX450 muffler system works pretty damn well, but as always we are constantly looking to try aftermarket pieces because as we all know, you are only as good as what you try! 

The Yoshimura RS-12 Stainless System is made in the USA, is rubber mounted to the subframe, its asymmetrical shaped muffler allows maximum capacity and incorporates a resonance chamber for managing sound and increasing usable power, the unique shape also provides more clearance for tire and brake caliper, has a new patent pending Precision Taper Fit (PTF) insert ring that can make it easy for the consumer to install and remove sound inserts as well as spark arresters, comes with a carbon fiber end cap and can be fully rebuilt with repacking kits that Yoshimura sells. If you’re looking to lose a little weight with the muffler, you will have to look towards the titanium system. The stainless system weighs in at 9.12 pounds, which is slightly heavier than the stock muffler, that comes in at 9.1 pounds. We aren’t necessarily looking to lose weight in this instance, as power, sound and reliability are more important to us with this unit. 

The stock muffler system is pretty damn good, as the power character of the KX450 is long and linear, but the stock KX450’s engine character could use a little more pulling power and more mid rpm response. Installing the Yosh RS-12 was painless enough and we really appreciated the rubber sub-frame mount that the Yosh muffler comes with. Having a rubber mounted rear muffler mount helps avoid the sub frame tab breaking off due to solid mounting. Once on the RS-12 is visually still big looking, but the RS-12’s exhaust note is so much better to the ears that we lost focus on how big the RS-12 looks. Out on the track we noticed how much easier the KX was to corners because there was less on/off feel from the engine on low RPM because the Yosh builds power a little more smoothly between 5000-7000 RPM. The RS-12 is less touchy to the riders throttle hand and to me that helped calm the chassis down in area 2-3 of corners. You will not get as much throttle response from the RS-12 as you do a FMF or a stock system, but to me this is a good thing. The mid range pulling power is what you will come to love from the Yosh system. Pulling power out of corners is noticeably better than stock and the rider can shift into third earlier without having to use the clutch in order to get the engine to recover (back into the meat of the power). Rear wheel traction was also an improvement on hard pack tracks as the KX450 had a better second gear flat corner sensation to the rear wheel than the stock system. Top end feels as good as stock with maybe a little more over-rev, so if you’re a little lazy the RS-12 can help you slightly in that area as well. 

If you’re looking for a more explosive rpm response from your KX450, the RS-12 may not be the muffler you want to go with, but if you want added pulling power out of corners as well as more rear wheel traction with a better exhaust note, then this Yoshimura RS-12 stainless system for your KX450 is a great buy. The benefit about stainless steel is that the overall construction of the muffler will last longer than titanium. Most of my practice bikes over time had stainless systems on it for the sake of durability. Slip fit titanium joints just don’t last as long as stainless. For $850.00, the RS-12 system is a good buy with quality construction that you expect from Yoshimura.  

ARC RC-8 Clutch Assembly With Aluminum Black Smooth Lever

I will admit that I am usually a stock perch/lever or a Works Connection Elite Perch/Lever kind of rider and although I have tried many different perch/lever set ups those are the two that I normally gravitate towards or back to. I have tested a lot of combos and have come to the conclusion that it’s tougher to make a better than OEM lever feel, perch and engagement feel. Now enter the ARC RC-8 Clutch Assembly With Aluminum Black Smooth Lever and I have found another perch/lever combo that I am genuinely happy with. Other perch/lever set ups that I have tried have either screwed up clutch engagement points with their odd ratios (and messed my corners up) or the lever is simply doesn’t have the right shape for my size large hands (lever shape is a key component to feeling comfortable with your rider triangle). Designing/making a perch/clutch lever is harder than most people think obviously. If you don’t get the lever ratio correct, you will have a clutch feel that is on/off or an engagement that is too grabby or slow feeling. Not easy. 

This ARC Billet Aluminum CNC-Machined lever assembly is the one that a lot of top teams run. If you haven’t met ARC Bob then you are really missing out. You might have heard me talk about him on some Racer X videos because the guy is a mad scientist of levers/perches. He will not rest until he’s created massive headaches for consumers due to the fact that he gives us so many damn options!  The features of this perch/lever combo start with the ARC aluminum smooth lever with a 27mm ratio, which I am a fan of. I am not a foldable lever kind of guy because I like a solid feel to my finger when I am pulling in the clutch. It just gives me a more positive feel and this lever seems to give me just that. Not to mention that the lever shape is one of only two shapes in the aftermarket lever business that I can get along with. There is a nylon sleeve that contacts the handlebar that allows for rotation in a crash, which is nice when you have a tendency to tip over in corners from time to time.

The cable 1/8 turn quick adjust has a large diameter rubber wheel that is easy to reach for/adjust on the line or in the air. yes, even if you’re a novice rider, you will be able to adjust it in the air! One of the other highlights is the "external pivot". The pivot bolt screws into the lever and the bolt rotates in the perch on replaceable bushings. Whaaaat! This eliminates almost all up and down play in the lever and gives me the positive engagement feel that I look for. In the world of tighter tolerances, this is what you want from a big four stroke. When you have horsepower, you could possibly get more vibration and that can radiate towards the ends of your levers. When you have a tighter tolerance in your levers, you get less vibration feel and more positivity on each end of your bike. It may not seem like much, but it’s the little things that make a difference when it comes to “feeling factory”.  It’s also nice that the clutch pull gets a little easier on the bike that I installed the ARC perch/lever on (2021 YZ450F).

At a cost of $205.00 for the complete perch/lever it’s a sizable investment, but with the quality of Bob’s work at ARC, I am happy to pay for something that I know I am going to love as well as last! ARC gives you a lot of ratio and lever options, so go visit the mad scientist of levers website at www.arclevers.com. 

Fasst Company Rear Brake Return Spring

Something that I have been using and quite frankly have forgotten to tell you guys about is the Fasst Co Rear brake Return Spring. Are you breaking rear brake pedal springs on a KTM or Yamaha? I seem to do this every few hours, so I decided to try out Fasst Company’s Rear brake Return Spring on the blue and orange machines. Fasst Co’s Rear Brake Return Spring offers tunable pedal resistance and a more controllable feel by placing the spring in compression instead of tension, which can minimize the "on-off" feel of some rear brake systems.

The pedal resistance can be adjusted by how much preload is placed on the spring. The Return Spring Kit also minimizes debris from jamming the master cylinder as well as eliminating the stock tension return spring that attaches to the pedal. The Rear Brake Pedal Return Spring Kit consists of spring, spring bucket and nut. The spring bucket contains the spring as well as seals the master cylinder with the stock rubber dust boot. 

Installation takes 10 minutes and the return spring kit gives you more of a positive feel, without a lot of slop, not to mention it’s way more durable than the OEM Yamaha or KTM rear brake pedal springs. Honda’s OEM return spring seem to last much longer, but nonetheless Fasst Co makes one of theirs for all Japanese and Austrian models. For 20 bucks it’s an easy one time investment on something you may purchase every few months. You can purchase or check out what they offer over at www.fasstco.com.