Testing Terms: Engine/Suspension *Updated*

If you learning more about your motocross bikes and also getting the lingo down, there is some help for you below. Here are some common terms that we use within the R&D industry that can help you explain what your bike is doing to tuners. Even if you just want to sound cool when you’re talking to your buddies, these terms will make you look like a regular factory test guy.

Suspension:

Pitching: This word is used when the rider lets off the throttle and the weight of the motorcycle forces the front end down. This usually happens when there is a lot of engine braking or the fork is too soft. The 2021 YZ450F was notorious for having a lot of this pitching when coming into a corner. Pitching can upset the chassis balance and can cause some oversteer through area 1 and 2 of corners. Pitching can also mean that a certain bike can squat (shock) too much under throttle out of corners causing the bike to have too much movement fore and aft. Pitching can make the machine seem unstable and cause the rider to not set up properly for corners. 

Hold Up: Hold up is mostly used when the fork or shock is riding too low in the stroke. When a rider is asking for more hold up he is usually wanting a stiffer compression setting so the fork or shock isn't “blowing through”. 

Harsh: This term has got to be the worst feeling to a rider. A harsh feeling is when the suspension is either too soft or too stiff. Yes, it can actually be both! If the suspension is too stiff the rider will complain about a harsh or firm feel through the handlebars. This stiff/harsh feel is caused by the suspension not being able to use all of its stroke. If the harsh feel is coming from the stiff side, opening the compression or the rebound can help alleviate some of this feeling. If the harsh feeling is coming from a soft sensation it’s because the suspension is riding too low in the stroke. Riding too low in the stroke can cause a harsh feeling because you are now in the mid stroke where the valving starts to ramp up to get stiffer. By stiffening the suspension a little you are now stiffening the initial part of the stroke which can actually make your bike feel plusher because your machine is riding higher up in the stroke around the track. “Harsh” is a tricky term because the cause of the harsh feeling can be from a too soft or too stiff of a setting.

Plush: I have never been a huge fan of this term, but the word plush means soft or supple feeling. If I hit something at speed most riders want their bike to feel plush and not harsh. However be careful when using this term to suspension techs as they may want to set your suspension up too soft. Plush can also mean the same with frame feel. For example, the KX450 has a plusher feeling to its frame than the of the Honda CRF450R. I like to use the term “bump absorption” more than the word plush. When the Kawasaki KX450 hits a certain square edge at speed, it has a better bump absorption feel than the Honda CRF450R. Off-road riders look for that plush feeling because they have less jumps to deal with and can hit roots/bumps at higher speeds. A softer compression setting or a faster rebound setting usually leads to a plusher feel.

Crust: We can thank air forks for this term. I came up with this term when I was at home during thanksgiving and I was watching my wife make a french apple pie. I always liked the middle of the pie more than the crust, so it immediately made me think of air forks. In order to get to the gooey goodness of the pie, I have to break through the crust right? Well air forks are the same thing! The top of the stroke of almost any air fork is called the crust because it’s usually has a hard/harsh feel initially and then you have some comfort. The crust usually gives you some deflection and a harsh feeling through the handlebars on small chop. We use the word crust because air forks usually feel like you have to break through the stiff portion of the travel in order to get to the softer/more forgiving portion of the stroke. WP has improved the air fork feel over the years so let's hope they continue down the path of a less crusty initial stroke on their air forks.

Empty: This term can be used when talking about engine character or suspension feel. When talking suspension empty usually means there is not a lot of damping feel. If you say “I feel like my end stroke is empty”, it means that it blows through or simply doesn't have any damping feel.  

Rigidity Balance: Rigidity balance is an important term when testing any chassis. If the bike has a firm feel and its rigidity balance is too firm it could mean that it corners excellent, but feels very harsh and has deflection on rough/fast straights. If the rigidity balance is too soft the bike can have a wallow feeling when under throttle as well as give the rider less confidence on braking bumps because of its unpredictable feel. Rigidity balance is something that every manufacturer works a lot on when developing their machine. A bike has to corner with precision, but also have enough comfort in order to have good bump absorption. A machine that has great rigidity balance is a Kawasaki KX450 because it turns well and can hit bumps at speed with a consistent feel.   

Performance: Performance is a word we used in the testing world when a rider is looking to ride at a higher level as well as be able to push the motorcycle without having it be too soft. Getting a chassis or suspension package to have better performance is basically asking the tuner that you understand that you’ll sacrifice some comfort, in order to get a machine that you can slam into obstacles harder without getting blow through. Usually riders that are faster or heavier want a performance based setting so they can hit jumps as well as bumps at a faster rate. 

 Comfort: A comfort setting is something most vet riders want so they don’t feel every little bump on the track. A comfort setting usually involves a softer setting that moves more in the stroke, but also can bottom out when hitting bigger jumps or larger bumps at speed. The 2021 YZ450F’s suspension package is a great example of blending both performance and comfort together. 

 Blow Through: This usually happens when hitting bumps/jumps hard and the suspension just dives without much damping force feel. If your suspension feels like it’s blowing through then you need to try and get a stiffer setting through clickers or internally with valving.  

Vague: Vague is usually a term used by describing front wheel traction. Front wheel lean angle traction can feel vague when the fork setting is too stiff, have the wrong offset triple clamps, or if you have the wrong compound front tire. A vague feel means that you will be washing your front tire out under lean angle and the bike may have less of a contact patch. Running too much air in your tire can also give you a vague feel.

 Damping Feel: Damping feel or force is the feeling of the suspension when moving down. Damping feel is used when explaining to tuners that you either have a soft feeling and need more of a stiffer setting. Damping feel can also be helpful/used when asked if the action of the suspension is too fast or too slow. 

 Deflection: Deflection happens when either a suspension setting is too stiff or a chassis setting is too rigid. Deflection happens when your front or rear end hits a bump/square edge and your bike simply doesn't absorb it. It’s like a pinball bouncing around from some side to side and can cause you to roll the throttle off in a hurry. Deflection also causes you to have less contact patch and makes the bike feel less planted. Going to a softer setting with the suspension or chassis usually alleviates some of this feeling. 

Contact Patch: Contact patch is a feeling of how much tire is felt underneath you. Contact patch can be increased by running less air pressure in your tires, running a softer suspension setting, chassis setting and/or increasing/decreasing offset. I like using this term a lot with my evaluations because without the feeling of a wide contact patch it will feel like you are running bicycle tires on your dirt bike. Having a wide contact patch feel gives you more confidence to roll the throttle on sooner when exiting corners. 

Engine:

Empty: This term is shared with the suspension side of things as well, but when a rider says that at a certain point that his power feels empty, he could mean that it’s a little lean or it just feels flat. Empty refers to a feeling where there is no more pulling power, or the power just simply feels flat (not exciting). 

Dirty Feeling: When a machine has a dirty feel to it that usually means the ECU/jetting is rich. A dirty feel means that the bike sputters, coughs, misses, etc., and most of the time it is due to a rich setting. Getting a dirty feeling delivery can also mean that your air filter element is clogged. You should clean it.

Recovery: Recovery describes how quickly a rider can get back into the meat of the power when missing a shift or when the machine is being lugged. Recovery is important because it gives the rider the confidence to know that if they make a mistake, the machine can get back up in the RPM’s and move down the track in a quick manner.

Excitement: Excitement is usually the initial feeling of the crack of the throttle anywhere in the RPM range. The Honda CRF450R is known to have a lot of excitement down low, but that excitement can also be a handful when rolling  corners. If a machine doesn't have enough excitement it also can suffer from poor recovery. See what I did there?

Lethargic/Lazy: This term is used for a machine that revs heavy or is slow to rev/spool up. A rich feeling can cause bottom end to feel lethargic/lazy feeling. Lethatgic can also mean that you will have to use the clutch a lot to get the engine into the meat of the power. 

Pulling Power: Pulling power is similar to torque feel. Pulling power is usually felt when the machine is exiting the corner or when driving up hills. The initial pop out of the corner usually reveals how much pulling power a certain bike has.

RPM Response: RPM response is the initial crack of the throttle anywhere in the RPM range. Excitement and RPM response can share the same meaning at times except when talking about having a lazy feeling engine character. Having good RPM response in an engine is important because it can help the machine feel lighter and more flickable.

Bottom End: Bottom end delivery usually refers to the power feel once immediately out of corners or when getting off the gate.

Mid-Range: Mid-Range delivery usually refers to the power feeling once exited from the corner and the rider is starting to make his shift into third gear. Mid-range feeling can be experienced in any gear but is only categorized by throttle position in the production testing world.

Top End: Top end is felt when a rider is full throttle and is accelerating down a straight. Top end can be felt in any gear but is most recognized in third and fourth gears on a moto track. How far the bike can pull each gear is usually categorized as top end.

Over-Rev: Over-rev is a term used by most testers as a sign of when the engine falls off its peak horsepower/top end. Having an engine with good over-rev means that the engine can pull each gear farther down the track without having to shift up a gear. Having an engine with a short over-rev means that the engine likes to be short shifted (up to the next gear early in the RPM range) and can't pull its gears very long.

Connectivity: This term is used when a test rider is trying to explain the feeling he has from this throttle hand to the rear wheel. Does his throttle and rear wheel feel connected to the ground or does the bike break loose or slide out? Good connectivity to the rear wheel allows for an easier-to-ride machine and can help the chassis settle down on rough tracks.

2022 Kawasaki KX450 Baseline Settings

Engine Feel: Just in case you were trying to decide on if the 2022 KX450 is better than the 2021, don’t stress because it’s the same bike! The 2022 engine character has great connection to the rear wheel, a smooth linear power that is smooth with snappy low end response, yet never seems like it has too much mid to top end, but does have more engine braking than a couple other 450 in its class. The mid range has a nice amount of meat and the smoother pulling power of the top end/over-rev is noticeable on longer straights or up hills. If you’re thinking about which coupler to use, (without changing the mapping) try the black coupler as it will help smooth out the low end rpm response (just know that if your KX450 is too touchy down low for you then this attached map below is the ticket). The KX didn’t lose mid to top end pulling power with the black coupler (compared to the stock green one) and I could ride the KX450 more aggressively through corners with the smoother power. However, if you have access to a KX Calibration Tool then see below for a map that helps low end as well as helps lengthen mid-top end.  

Weight Feeling (Chassis): I am able to lay the KX450 down with ease (initial lean) and cut down under a blown out rut fairly easy but once in the rut the KX still feels long. I also get a little twitch on de-cel (which can be fixed with a fork spring change), but it wasn't a horrible or un-easy feeling. Straight line stability is still the same straight and arrow Kawasaki feel that you expect, but with added traction. The frame absorption is the best attribute of this machine and other manufacturers should take notice of how well this KX450 feels when the track goes to crap. The whole bike feels friendlier than any other 2021 machine on square edge and the only other one that comes close in comfort is the Yamaha YZ450F. 

Suspension Comfort: The 2022 Kawasaki is so much more balanced than previous generation KX450’s and I was able to set the front end down where I wanted to without feeling like the front end was going to snap my wrists. The fork has tons of comfort, but is also too soft/low on de-cel for my liking. At tracks with hills or sizable jumps, the fork was too low in the stroke and bottomed too many times. Going stiffer on the compression only hurt de-cel bump comfort, so I settled on going slower on the rebound, which helped some. The shock is soft as well on slap down landings, but going eight clicks (two full turns) in helped keep the rear end up and thus helps wallow feeling. This setting will get you by on most tracks, but do yourself a favor and read the recommended suspension settings below for optimal balance of the KX450. The recommended settings below will help with hold up and ride comfort.

Cornering/Chassis: The 2022 KX450 is a “neutral” cornering machine. I am able to get more rear wheel bite than a Yamaha YZ450F, but I am still able to turn on the front end fairly well. I had a rear end steering tester with me when we did the intro and he mentioned how well it backed into corners still. I thought front end bite from area 2-3 of corners was still acceptable, but got even better with a heavier fork spring. I say “area 2-3” because the KX450 still does have a slight vague feel on entrance of corners, so increasing spring rate prevents the front end from diving, which in turn prevents your front tire from pushing on entrance. 

Rider Triangle: The footpeg to seat to handlebar ratio is great! The seat is flat, which puts me more on top of the machine and the Renthal 839 Fatbar makes the bike feel very friendly for a wide range of riders. 

 Brakes: Do yourself a favor and get a 2021 KX250 rear disc and hanger. The 250mm disc is too grabby and really screws up my corners/braking points. The rear end will slide when I don't expect it and this causes my corners to be herky/jerky. Go back to the 240mm disc on the 21 KX250 and live life happier. 

2021 KX450 Suspension Settings:

After almost 25 hours on the 22 KX450 these are the best settings for a wide range of riders. This setting is based around comfort and will give the rider the most confidence. Use this set up until you get a re-valve. Once you re-valve, use recommended suspension tuners spec. 

Fork: 

 Spring Rate .51 N/m Spring (.50 N/m is stock) *If B level rider and over 200 pounds .52 N/m springs are also a great option*

 Oil Level: Standard

 Compression:10-11 clicks out

 Rebound Range: 9-10 clicks out

 Fork Height: 3 mm

 Shock:

 Spring Rate: .54 N/m (190 pounds or over, try .56 N/m)

 Low Speed Compression: 13 clicks out

 High Speed Compression: 1 1/8 turns out

 Rebound: 10 out

Coupler/ECU Setting:

The engine on the 2022 KX450 in stock is smooth off the bottom and easy to ride, but does have a little dip from mid to top, so I created this map to help fill that dip in and make it pull slightly longer. You will notice even more of a linear (more control at low RPM) pull down low without any jerky feeling through corners. With this map installed it helped settle the chassis down through long ruts and improved overall traction feel. In the testing world we call this "cornering stability". With this map installed it helped the 2022 KX450's cornering stability, especially on intermediate terrain. You can use any coupler with the Kawasaki FI Calibration Tool to create this map. 

Aftermarket Mufflers: I have tried a lot of mufflers with the KX450 and to me the FMF and PC have the most noticeable change to the engine character of the KX450. As ugly as the stock muffler is, it’s a very good muffler for a broad range of power delivery. However, when you go to a FMF muffler, do yourself a favor and look at this article on how to make it rubber mounted. https://www.keeferinctesting.com/offroad-testing/2020/10/8/how-to-save-your-subframe-on-your-2019-2021-kawasaki-kx450. 

 We have broken a subframe tab because the FMF is a solid mount system, not rubber mounted. This doesn’t necessarily mean that the subframe tab will not break if it’s rubber mounted as we have broken the tab on the subframe with the stock muffler as well (which is rubber mounted).

Pro Circuit Fork/Shock Re-Valve (2021 Husqvarna FC450)

Written By: Joe Oehlhof

The KTM, Gas Gas, and Husqvarna umbrella was divided up by brand to target different types of consumers.  KTM being the high end, ready to race model, Gas Gas being the affordable yet sufficient to go racing on model, and the Husqvarna being the mellower vet friendly all-around type of bike. 

So, when Kris gave me the Husqvarna 2021FC450, my goal was to see if I could improve on it.  My initial step was to ride the bike and shake it down in stock form, which I wrote about in a previous article. Next up was to improve upon the stocker based on what I found on the initial rides.  As far as power, this is still a 450 and has plenty of motor, it’s just a question of where do you want the power and how do you go about moving it to suit you.  So, I didn’t want to make this my focus, I wanted to work on the chassis and suspension. 

For 2021 Husqvarna decided to set up the chassis and suspension of the FC450 to fit the smaller/vet rider/off-road and trail rider. They did this by installing 10mm shorter forks, configuring the linkage to drop the rear of the bike 10mm and as a result of lowering the rear, they also had to limit the depth of the shock stroke to prevent the tire from hitting the back of the air box. With the bike set up this way, the on-track feel was for me, a bit harsh on the choppy bumps. The rear end felt as if it were on a different/lower level than the front of the bike and the overall chassis feel was really stiff. One area that was a positive for me was the lower front end gave me the ability to turn down earlier in corners and hug the inside lines. Once I had this info, I went to Luke and the guys in the suspension department at Pro Circuit to see what we could come up with. I wanted to keep the 10mm lower forks, but I did want to raise the rear end to get more of a balanced feel. When Luke called and said everything was ready, I picked up the stock suspension, sprung and re-valved for my weight/riding ability, and a different linkage consisting of a different rod length and knuckle to try and accomplish what I wanted. I bolted it up to the bike and went and tested it at three different tracks – Fox Raceway, State Fair MX, and Glen Helen. 

When riding the bike, I immediately noticed the balanced feel due to the new linkage.  I no longer had the two separate level feeling (or unbalanced feel) that I did with the stock linkage. Along with the re-valved and a spring change to the shock, I instantly had a better feel for where my rear tire was placed, significantly better bump absorption, and a more planted, stable feel on corner entry. I didn’t have any issues with the bike in stock form with jump takeoff or landings, but these areas were slightly improved with the correct spring and valving tailored to me.   

Like I mentioned before in stock form, the forks had a harsh, unstable feeling. I wasn’t sure if this could be improved with different triple clamps or just a re-valved AER fork. So, I decided to try the Pro Circuit re-valved fork and keep the stock clamps. The fork performed slightly better than stock on jump take offs and landings, but the areas where I noticed the biggest improvements were front end traction/feel and I got that initial plushness back on small chop that the stock forks didn’t have. This gave the bike an overall more compliant confidence inspiring feel when the track got rough late in the day. Another area that I didn’t anticipate improving on was the ability to turn down even tighter and stick to the inside line with the same speed as a wider line. I believe this was better because the forks had better holdup and it allowed me to push the bike into and around corners at a higher speed without dive. 

So at the end of the day, this Pro Circuit suspension mod helped me achieve the areas the FC450 needed to be better in, as well as help me have a better level of comfort while trying to push this older moto body back into shape. I still would like to try a different triple clamp set up and possibly different engine hangers to see if I could improve even further on the harsh chassis feeling that I get at some tracks.  All in all, big improvements with some pretty basic changes that make a good bike even better.  If you are looking to getting these same improvements, call PC at 951-738-8050.  Mention this article and they will get you set up and maybe possibly a discount. 

2021 KTM 250 SX-F Baseline Suspension, Rider Triangle, And Gearing Settings

My son and I have been riding the 2021 KTM 250 SX-F heavily the past few months and have come up with some settings for each of us that may help you out with your orange 250 four stroke machine. If you’re looking for a good place to start, these settings below worked well for a wide variety of tracks that we tested at. Getting a setting that ranges from 130-175 pounds is tough to do but after a few months of playing around we thing we found a setting that can make you comfortable. Below are some suspension, gearing and rider triangle settings that you can apply to your orange brigade at home. 

Suspension: (160-190 Pounds)

Fork: 

C: 15

R: 11

Height: 4mm

Air: 10.7 Bar

Shock: (Spec #AK2S)

LSC: 13

HSC: 1.5

R:11

Sag: 105mm

Suspension: (130-155 Pounds)

Fork: 

C: 11

R: 10

Height: 4mm

Air: 10.4 Bar

Shock: (Spec #AK2S)

LSC: 15

HSC: 1..75

R: 11

Sag: 105mm

Gearing: 

In stock form the 2021 KTM 250 SX-F comes with a 14/51 but for heavier riders above 170 pounds a 14/52 or even a 14/53 works better in most conditions. Why? It allows the rider to get into third gear more and let the KTM 250 SX-F pull their heavy asses around the track better. For lighter riders under 150 pounds the stock 13/51 gearing is just fine as the lighter riders can use 3rd gear a little early without the detrimental affect of not having enough recovery when shifting too early. 

Rider Triangle: 

The stock Neken handlebar is rigid/harsh to the hands so go with a Pro Taper bar. If you’re a Renthal guy please contact me for specs at kris@keeferinctesting.com. See specs below: 

Height: 5’5-5’9 = Husqvarna Stock Pro Taper Bend

Height: 5’9-6’2 = SX Race Pro Taper Bend or YZ High Pro Taper Bend

Throttle Feel:

If you find yourself having a sticky or hard twist to your throttle, you can replace your throttle cables as the stock cables will only last around 20 hours before they start to feel like crap. No matter what you do, the cables will never feel the same even if you lube them. You might get a free feel after lubing the cables for a bit, but soon thereafter your throttle will feel harder to twist once again. If you’re looking to spend a little money for an aluminum throttle tube and want to  help the feel of your throttle, I recommend the ZRT throttle. This throttle tube makes the pull have almost zero drag and is a tough SOB. There is some set up/prep time to this throttle (cutting the right side of the handlebars a 1/2 inch), but it can help the pull over the long haul.

TOP 5 MAINTENANCE ITEMS:

1. Fuel Filters: If you’re a KTM owner, do yourself a favor and put a couple of these in your toolbox just in case. Fuel filters can get clogged on all KTM’s and this can cause damage to your fuel pump or possibly not allow your bike to start properly.

2. Throttle Cables: If there is one thing that DOES NOT last on KTM’s it is the throttle cables. Every 15-20 hours I will have to replace the throttle cables to ensure that my throttle doesn’t feel hard or sticky when twisting. Originally I thought my throttle tube was dirty or maybe the right side of the handlebar had dirt on it, but I found out through a couple KTM mechanics, that the throttle cables simply wear out. You can’t lube them or clean them out as it will only make the throttle feel better for a short amount of time. Get some 

3. Check All Spokes/Sprocket Bolts: KTM spokes always come loose near the rim lock so make sure you pay attention to all the spokes after every ride. If you don’t check them constantly you will lose or break a couple. 

4. Check Engine Mounts/Swingarm Pivot Bolt: Always check the torx bolts that hold the top engine hangers on the bike. After break in, these will loosen up a bunch, so you might need some blue Loctite on the threads. After you do this, please continue to check these as they still back out from time to time. The torque spec on these bolts are important to the ride attitude of these KTM’s. Also the KTM’s come with frame guards and that means you will not know (until it’s too late) when your swingarm pivot bolt  backs out. Take off your frame guard and check pivot bolt regularly. While you’re at it, get the Acerbis frame guards as they last longer and have better grip than the stock ones. 

5: FI Indicator Light: The little FI indicator light bulb will fall out of the rubber casing as soon as you get past 10 hours. The best thing to do is put a little silicone inside the rubber casing, so the light bulb as well as the wire doesn’t flop around.

2021 250 MX Baseline Stock Suspension Settings Bible

Here is your one stop shop for some baseline suspension settings for all (except the Suzuki) the 250 motocross machines. These settings are a great start for anyone between 150-180 pounds. If heavier springs are needed the below specs will specify this. If you’re asking yourself ,why not gives some specs for riders under 150 pounds, don’t fret, email me at kris@keeferinctesting.com and I can try to walk you through some options. -KK

2021 Honda CRF250R:

In stock form the Showa suspension on the 2021 Honda CRF250R has decent comfort on de-cel bumps, but lacks a little hold up for riders ranging from 160-190 pounds. If you’re over 190 pounds going up a spring rate on each end is your ticket to a better handling CRF250R. After riding with this setting below at more than three different tracks, more than one time around, I figured out that this baseline suspension setting gave the 2021 Honda CRF250R the most “track toughness”. If you happen to feel like the fork is harsher (through the mid stroke) with this setting, simply open up the rebound (faster) back to stock setting. This will help free up the fork slightly under front end load (off-gas). The shock needs just a little more hold up under acceleration so simply going stiffer/slower on low speed compression/rebound gives the rider more comfort and added traction out of corners. I tried experimenting with high speed compression, but the Honda is finicky with high speed. Going stiffer on high speed compression (shock) put too much weight on the front end (fork) creating a harsher feeling front fork.

Fork:

Spring Rate: 4.8N/mm

Height: 3mm 

Compression: 6-7 clicks out 

Rebound: 10 clicks out 

Shock:

Spring Rate: 52N/mm

Sag: 102-103mm

High Speed Compression: 2-5/6

Low Speed Compression: 9 clicks out 

Rebound: 5 clicks out

2021 Kawasaki KX250:

The 2021 KX250 to me has a better suspension feel than the KX450 as well a better hold up. The KYB suspension has a wide range of comfort for different size riders so stock springs should suffice unless you’re over 180 pounds. If you’re over 180 pounds then going to a 5.0N/mm fork spring (like last year’s fork) and 56N/mm rear spring and softening up the compression a couple clicks on each end and that should increase the comfort for you heavier dudes.

Fork: 

Spring Rate: 4.9 N/mm

Height: 4mm

Compression: 9 clicks out 

Rebound: 10 clicks out 

Shock:

Spring Rate: 54 N/mm

Sag: 102-103mm

High Speed Compression: 1.25 turns out

Low Speed Compression: 9 clicks out

Rebound: 11 clicks out 

2021 Yamaha YZ250: 

Much like the chassis, the 2021 suspension feels firmer (compared the 2020), holds up more in the stroke slightly, yet still has that KYB free feeling movement (unlike a Showa feel where it moves less with a dead feel) that is very active on the track. That active feel translates into a a front/rear end that follows the ground well under small chatter and bigger/softer braking bumps. I did have to go a little firmer on both ends for my style of riding, but it didn’t take long at all to feel comfortable. Track Toughness of the 2021 Yamaha YZ250F is better than the 2020, but if you’re north of 180 pounds you might want to drop in a set of 4.8N/mm fork springs and live happy! 

Fork: 

Spring Rate: 4.7 N/mm

Height: 4mm

Compression: 8 clicks out 

Rebound: 9 clicks out 

Shock:

Spring Rate: 56 N/mm

Sag: 104mm

High Speed Compression: 7/8-1 turn out

Low Speed Compression: 8 clicks out

Rebound: 9 clicks out 

2021 KTM 250SX-F: 

Always remember that a WP AER fork needs more time to break in than any other fork on the market. Your AER fork will need at least 5-6 engine hours to fully break in. If you feel like your fork is stiff/harsh before that, don’t fret yet, as this is a common feel among these forks. These KTM/Husqvarna/Gas Gas settings are for riders anywhere from 150-180 pounds. Lighter riders under 150 pounds will need a slightly softer air setting (around TKTK bar), but can use the same clicker adjustment readings. 

Fork: 

Spring Rate: 10.6-10.7 bar

Height: 5mm

Compression: 11 clicks out (with 10.6 bar) 15 clicks out (with 10.7 bar)

Rebound: 11 clicks out 

Shock:

Spring Rate: 42 N/mm

Sag: 102-103mm

High Speed Compression: 1.75-2 turns out

Low Speed Compression: 11 clicks out

Rebound: 12 clicks out 

2021 Gas Gas MC250:

Fork: 

Spring Rate: 10.6-10.7 bar

Height: 5mm

Compression: 11 clicks out (with 10.6 bar) 15 clicks out (with 10.7 bar)

Rebound: 10 clicks out 

Shock:

Spring Rate: 42 N/mm

Sag: 102-103mm

High Speed Compression: 1.75-2 turns out

Low Speed Compression: 11 clicks out

Rebound: 11 clicks out

2021 Husqvarna FC250: 

Due to the lower nature of the Husqvarna setting, we preferred to go a little stiffer with this set up to get more comfort on the Husqvarna suspension.

Fork: 

Spring Rate: 10.7-10.8 bar

Height: 5mm

Compression: 14 clicks out 

Rebound: 9-10 clicks out

Shock:

Spring Rate: 42 N/mm

Sag: 100-101mm

High Speed Compression: 1.5 

Low Speed Compression: 10 clicks out

Rebound: 11 clicks out 

2021 Kawasaki KX450 Baseline Settings

Engine Feel: Just in case you were trying to decide on if the 2021 KX450 is better than the 2020, even though not much has changed, there is actually a little difference because of the new clutch. The 2020 comes on quicker with a lighter, more free-revving feel and has less engine braking, but the 2021 has more connection to the rear wheel, more control under throttle and has a little more engine braking, which for me is a good thing. I am usually not a guy who likes to de-tune a stock 450cc motocross bike, but the 2020 Kawasaki simply is too crisp from 0-5% throttle opening on slicker/hard pack tracks. The 2021 KX450 comes on a little smoother down low and feels like the new clutch helps with rear wheel traction.  

The mid range has a nice amount of meat and the smoother pulling power of the top end/over-rev is noticeable on longer straights or up hills. I didn’t lose mid to top end pulling power with the black coupler (compared to the stock green one) and I could ride the KX450 more aggressively through corners with the updated clutch. This is an impressive power plant!

Weight Feeing (Chassis): I am able to lay the KX450 down with ease and cut down under a blown out rut almost as easy as a KTM/Husqvarna. I do get a little twitch on de-cel (which can be fixed with a fork spring change), but it wasn't a horrible or un-easy feeling. Straight line stability is still the same straight and arrow Kawasaki feel that you expect, but with added traction. The frame absorption is the best attribute of this machine and other manufacturers should take notice of how well this KX450 feels when the track goes to crap. The whole bike feels friendlier than any other 2021 machine on square edge and the only other one that comes close in comfort is the Yamaha YZ450F.   

Suspension Comfort: The 2021 Kawasaki is so much more balanced than previous generation KX450’s and I was able to set the front end down where I wanted to without feeling like the front end was going to snap my wrists. The fork has tons of comfort, but is also too soft/low on de-cel for my liking. At tracks with hills or sizable jumps, the fork was too low in the stroke and bottomed too many times. Going stiffer on the compression only hurt de-cel bump comfort, so I settled on going slower on the rebound, which helped some. The shock is soft as well on slap down landings, but going eight clicks (two full turns) in helped keep the rear end up and thus helps wallow feeling. This setting will get you by on most tracks, but do yourself a favor and read the recommended suspension settings below for optimal balance of the KX450. The recommended settings below will help with hold up and ride comfort.

Cornering/Chassis: The 2021 KX450 is a more “neutral” cornering machine than in previous years. I am able to get more rear wheel bite than last year, but I am still able to turn on the front end fairly well. I had a rear end steering tester with me when we did the intro and he mentioned how well it backed into corners still. I thought front end bite from area 2-3 of corners was still acceptable, but got even better with a heavier fork spring. I say “area 2-3” because the KX450 still does have a slight vague feel on entrance of corners, so increasing spring rate prevents the front end from diving, which in turn prevents your front tire from pushing on entrance. 

Rider Triangle: The footpeg to seat to handlebar ratio is great! The seat is flat, which puts me more on top of the machine and the Renthal 839 Fatbar makes the bike feel very friendly for a wide range of riders. 

Brakes: Do yourself a favor and get a 2021 KX250 rear disc and hanger. The 250mm disc is too grabby and really screws up my corners/braking points. The rear end will slide when I don't expect it and this causes my corners to be herky/jerky. Go back to the 240mm disc on the 21 KX250 and live life happier. 

2021 KX450 Suspension Settings:

After almost 20 hours on the 21 KX450 these are the best settings for a wide range of riders. This setting is based around comfort and will give the rider the most confidence. Use this set up until you get a re-valve. Once you re-valve, use recommended suspension tuners spec.

Fork: 

Spring Rate .51 N/m Spring (.50 N/m is stock) *If B level rider and over 200 pounds .52 N/m springs are also a great option*

Oil Level: Standard

Compression:11-12 clicks out

Rebound Range: 10-11 clicks out

Fork Height: 2-3 mm

 Shock:

Spring Rate: .54 N/m (190 pounds or over, try .56 N/m)

Low Speed Compression: 16 clicks out

High Speed Compression: 1 1/8 turns out

Rebound: 10-11 out

Coupler/ECU Setting:

The engine on the 2021 KX450 in stock is smooth off the bottom and easy to ride, but does have a little dip from mid to top, so I created this map to help fill that dip in and make it pull slightly longer. You will notice even more of a linear (more control at low RPM) pull down low without any jerky feeling through corners. With this map installed it helped settle the chassis down through long ruts and improved overall traction feel. In the testing world we call this "cornering stability". With this map installed it helped the 2021 KX450's cornering stability, especially on intermediate terrain. You will need to use the white coupler and use the Kawasaki FI Calibration Tool to create this map. 

Aftermarket Mufflers: I have tried a lot of mufflers with the KX450 and to me the FMF and PC have the most noticeable change to the engine character of the KX450. As ugly as the stock muffler is, it’s a very good muffler for a broad range of power delivery. However, when you go to a FMF muffler, do yourself a favor and look at this article on how to make it rubber mounted. https://www.keeferinctesting.com/offroad-testing/2020/10/8/how-to-save-your-subframe-on-your-2019-2021-kawasaki-kx450. 

We have broken a subframe tab because the FMF is a solid mount system, not rubber mounted. This doesn’t necessarily mean that the subframe tab will not break if it’s rubber mounted as we have broken the tab on the subframe with the stock muffler as well (which is rubber mounted).

This guy knows a thing or two about muffler brackets.

2020 Suzuki RM-Z250 Blue Collar Project Part Two

Kris recently assigned me the 2020 RM-Z 250 to test and do a little project with. I have to say I’ve been having a blast riding it and trying to make it better. It’s a super fun bike to ride, despite the sometimes bad reputation it gets. If you haven’t read Part 1 of our build, check it out here: https://www.keeferinctesting.com/motocross-testing/2020/6/3/2020-suzuki-rm-z250-tipstricks-part-1

For a little recap of Part 1, the RM-Z is known to be a bit down on power in comparison to its competitors. Our goal was to find more power, without breaking the bank. Often times moto media outlets tend to throw the book at bike builds and I get why, but it’s fun to build a badass bike with all the exotic parts, but it’s not very practical for your real world rider, that is working 9-5. With that being said, we were able to find more power and make the RM-Z a little more exciting to ride, just by opening up the airbox and installing a pipe. 

Continuing with the trend of giving the RM-Z more air, I tested the Super Flow Air Filter Kit from No Toil. The kit comes with a new air filter cage that eliminates the stock backfire screen and also comes with a high flow air filter. On the track I noticed more throttle response and an overall quicker revving/more free feeling engine character. In stock trim, the RM-Z feels choked up, like it’s starving for air. With my no cost mod of opening up the airbox, the No Toil kit completes the mission of getting more air through the intake. I was surprised at how big of a difference it makes in mid corner (area 2) recovery and overall excitement across the RPM range. Expect to find yourself upshifting sooner exiting corners as the engine revs up much quicker allowing you to pull taller gears sooner. 

My next mod was installing Rekluse’s Torq-Drive Clutch Pack.  It’s a low cost alternative to their complete Torq-Drive kit. I’ve raced with Torq-Drive clutches for years in SX. They are an absolute must have for Supercross whoops, as it’s almost impossible to make them slip, but I’ve never tested a Torq-Drive back to back on an outdoor track and on a 250F for that matter. The clutch pack is easy to install as it fits directly into your stock clutch basket/hub and it’s almost a third of the price of their complete kit. 

The very first thing I noticed was how easy the clutch pull was. I’ve never been picky about an easy clutch pull, but I have to say, it’s nice having a buttery smooth feeling at the lever. On the track you’ll feel improved bottom end exiting corners and an increase in pulling power throughout the whole RPM range. It’s an interesting feeling, because I wouldn’t say that the bike makes any more power with the Rekluse, but it just does a better job of putting the power you already have to the ground. As Keefer would say “more linear”.

I tested this clutch kit at Glen Helen and where I noticed the biggest difference was down the deep tilled start straight and up the hills. I felt like I could rev the bike less yet still get more forward drive. Rather than revving high and getting a slight amount of slip with the stock clutch. I’d imagine as I continue to make mods and find more power that the clutch will make an even bigger difference. Where the stock clutch would slip under a heavy load, the Rekluse hooks up and drives forward. With a couple pretty simple mods we’ve  been able to find some more power and make the RM-Z motor more competitive, and for a relatively low dollar investment.

My next goal was to improve the chassis. If you’ve ridden the stock 2019-2020 RM-Z250 you’ve probably noticed the forks are STIFF. I’m a 180 lbs Pro and they are too stiff for me, so I can’t imagine a normal weekend warrior type of rider. Unless you’re 200+ lbs or just want an extra stiff setup, expect to have your suspension re-valved or at the least re-sprung. 

Of course we sent the suspension to Race Tech where they re-valved it with their Gold Valves and installed lighter springs front and rear. I’m usually very picky on my suspension setup, and I have to say Race Tech nailed this one first try. The chassis on the RM-Z is still slightly on the stiff side, but it’s very predictable and corners like a dream. Race Tech’s mods gave me more comfort in the front end end and overall calmed down the chassis. I truly have no complaints about the suspension (which is super odd to me), I found the comfort I was looking for, but still retained good bottoming resistance and hold up on big hits. Having a softer setting helped the bike settle more and turn even better than stock, and also gave me a little more stability through high speed chop. 

I’ve truly been having a blast riding the #RMaRMy. Being a 450 guy for the last few years, it’s been super fun to ride and the few mods we’ve made, have made a huge improvement in making the bike more fun, as well as more competitive. I have a few more things in mind that I think will make to 2020 RM-Z250 even better, so stay tuned for a Part three coming soon. 

Kreft Suspension For Husqvarna TE300i (XPlor fork)

Written By: Michael Allen

Let’s be honest, as riders we have all probably uttered these words to a suspension tuner, “I want it plush, but stiff”. I would imagine that every suspension guy has heard that phrase and grits his teeth every time he hears it. That is where Kreft comes in with their revolutionary design of being able to “revalve” the fork with just the turn of a dial instead of taking the fork apart and actually putting different shims in the fork itself. Admittedly when it comes to the internals of how a fork works I am no specialist, but when Matt from Kreft broke it down and explained it to me in dumb dirt bike rider terms, it was very interesting and made a lot of sense. 

I have worked with many suspension companies over the years and for the most part they work the same in terms of pick up and drop off. This is the first thing that stood out to me when I started working with Kreft: The first step of the process is an initial phone consultation where you actually build somewhat of a relationship with the representative. You go over the basics, like what bike you’re riding and your measurements, but you also get into what you want to feel out on the trail. Along with that you get a crash course on what makes Kreft different and how their system works. From there they send you an empty box with prefect (I really mean perfect) cutouts for your specific fork and shock. They are so detail oriented they even send you bleeder screws, so just in case you have button bleeders they can be replaced so that your forks don’t leak and ruin the box in transit. The professionalism is second to none while still being personable as well as very helpful and explanatory. 

Aside from the obvious spring rate change and re-valve, the fork gets Kreft’s “Re-valve Control”. The way it was explained to me was that on a standard fork the shim stack nut is tightened down on the top of the shims and in that case, the valving is whatever the tuner’s spec is. The valving itself cannot be changed without fully dissembling the fork and changing the actual shims. The only adjustability on a standard fork is compression and rebound clickers. What Kreft does is use a spring that can have more or less pressure put on it with the adjustment of the re-valve Control knob on top of the left fork. What that spring pressure does is put more or less pressure on the shim stack itself. This gives the rider the ability to make “valving changes” on the fly to adapt to a wide range of terrain and disciplines of off-road riding. With the Kreft fork you now have the standard compression and rebound clickers as well as the re-valve control. In doing all these changes Kreft has also changed the damping forces in the left and right fork tubes. The XPlor fork has unbalanced forces in stock form, making the left tube do the majority of the work. What this does is give the left fork more of a chance of having oil cavitation, resulting in poor damping performance. The final thing that was done to the forks was the Microfinish which is said to work better than DLC coating (and is far cheaper) to reduce friction creating less drag and seal stiction than the stock finish.

To compliment the fork changes, Kreft internally changes the shock components to get the greatest potential and best balance of the low and high speed tuning circuits. If the circuits aren’t balanced and one is doing far more than the other there is a greater chance for cavitation which results in poor performance. Once the circuits are balanced and cavitation is no longer occurring, the changes that are made to the clickers have a much larger adjustment range and are far more effective. Along with the spring change on the shock, Kreft also installed the X-Trig preload adjuster which I had never used, but holy shit that thing is awesome!

Now that I have explained all the technical info (to the best of my dumb dirt bike test rider ability) let’s get down to how it all works out in the real world. As I said in my initial test of the TE 300i, any type of riding other than very tech slow trails meant that the TE was going to feel out of place. The fork was extremely divvy when on the brakes or even just when transitioning off throttle. This unbalanced pitching feeling caused the bike to be unpredictable when cornering. In addition to that, anything that resembled a g-out made the bike bottom and rebound too quickly, which doesn’t necessarily give the rider very much confidence, especially in a racing situation. The one race that I did in stock form made it clear that I was having to check up for obstacles that normally wouldn’t phase me, so I knew something had to be done. 

After getting the stuff back from Kreft I bolted it on and read through their extensive welcome packet, which was super informative. I set my sag (which they had very close already) and headed out to my favorite trails, which have a plethora of different types of terrain. The first thing I noticed was that the unbalanced feel was no longer an issue. Now when I enter coroners the bike stays further up in the stroke and is much more predictable. My biggest concern was that after telling Kreft that I mostly ride faster paced desert terrain, I was worried that they would make it too stiff and I would no longer have the compliance in the tight technical terrain. Like I said in the beginning of this story, I basically told them that I want it firm, but soft and to my surprise, Kreft gave me my cake and let me eat it too. After becoming more confident and being able to pick up the pace, I found myself going into g-outs as well as slamming into bigger whoops with more speed. Initially the fork had a slight quick feel that would cause the front tire to lose traction, but after slowing down the rebound three clicks, the bike stayed planted much better following hard landings.

The only other issue I had with the front end was that I felt I still needed more bottoming resistance. I tried going in on the re-valve control, but that wasn’t necessarily the feeling I was looking for. While going in on the re-valve control helped my issue, it took away a little of the initial plushness that I liked. After talking with Kreft, they recommended I simply get a syringe and add 15ml of oil to both forks. After doing this I was able to keep the initial settings on the re-valve control while still getting the bottom resistance I was looking for. When it came to the shock, Kreft was really close on the setting I loved out of the box. I had a slight kick in the rear on de-cel bumps, but it was only off-throttle. To combat this Kreft recommended that I open up the high speed compression all the out. After doing this the kick was eliminated, but I felt the bike was bottoming too frequently, so I followed their recommendation and worked the high speed adjuster in by ¼ turn at a time until I found the balance that I desired. One misconception that I think a lot riders have (I used to as well) is that if your bike is bottoming it’s too soft. It’s perfectly ok for your bike to bottom if the bump or landing warrants it. Bottoming out from time to time means you are using all of your suspension travel. This is what you want! Use all the travel, but still have a comfort/performance blend for your type of riding.  

Kreft prides themselves on having great customer service, provide a high end product and also a product that has a very wide range of adjustability. When they told me that I could ride technical single track with the same bike that I rode at the moto track, I was skeptical. My last test before writing this article was doing just that, I went to the moto track. Before riding I looked at their recommended setting for moto, adjusted it and started moto’ing. Now was it just as good as a moto setting would be if the suspension was built for moto? Not entirely, but the adjustments for moto made the bike comfortable enough on the track that I was jumping every obstacle without blowing through the travel as well as cornering with confidence. I didn’t feel like the suspension was holding me back by any means and I wasn’t out of my element on this bike. The mere fact that one bike can be capable of such different disciplines with small adjustments is super impressive. I think that Kreft is really on to something and will only be getting more recognition as time goes on. 

The price breakdown is as follows: Xplor Re-valve Control and Re-valved shock is $1,200 (including seals and fluid), the addition of springs (if needed), Microfinish and X-Trig spring adjuster brings the total to $1,800. Like I said before, Kreft prides themselves on being very high end and in my opinion you get what you pay for. Every part of dealing with Kreft was top notch, from their box, customer service, quality of parts, and performance of the suspension was very impressive. If you are in the market to fix your 4CS, AER, or Xplor suspension, I would highly recommend giving Kreft a call. If you have any questions about the performance of the Kreft setup on the TE 300i feel free to reach out to me at Michael@keeferinctesting.com. That being said, if you have any technical questions about the parts itself reach out to them because I’m just a test dummy and won’t be able to answer your questions. Kreft’s contact is 541-797-0700 or email them at Info@Kreftmoto.com. 

2020 Kawasaki KX450 Engine/Suspension Updates (Living With Series)

Written By: Joe Oehlhof

If your like me after having a bike for a few months you begin to get a little more particular with your bike and start wanting to try different things. If you read my article on the building of this bike (for the Vet National at Glen Helen) you know I threw a lot of things at it in a short amount of time and got the opportunity to try some high dollar modifications. You would also know that once I raced the event I wasn't necessarily pleased with my result and felt I lost a bit of that comfy feeling I once had with this bike. Initially I thought it was due to not racing at those speeds and pushing my limits, but in the weeks after I couldn't get that feeling back. I was somewhat puzzled and decided to go back to the stock base and start over. The reason for this wasn't because I didn't believe the modifications I had done weren't the right ones, but I knew there was a couple areas that needed a tweak here and there to find that feel. This is one of the things that’s hard about testing as well as fine tuning a bike, you can get lost and off track, but still be really close to that ultimate setting. I felt this was where I was exactly at, so going back to my opening statement, I started to try different things. 

 The first area I focused on was the suspension, but mainly the shock. In stock form the shock has some decent comfort, has a softer initial feel, which can give you comfort in those smaller acceleration bumps yet can provide predictable traction when the track begins to dry out and conditions worsen. For a guy who is 190 pounds like myself or an intermediate to pro level rider, the stock shock wallows a little on rolling whoops or g-outs and can bottom on big landings. It also tends to squat a smidge too much when exiting turns, which can result in a harsh feeling. I took the info I had and talked to my guy Luke at Pro Circuit and he said he had a couple different settings he'd been working on that addressed the issues I had. Now as you may also know I did have the A-kit cartridge set up for the Showa forks when I raced the Vet Nats. I unfortunately I couldn't keep those, so I had PC set up my stock forks for a comparison and additionally I wanted to do some lower budget items for those frugal consumers like myself.

Let's start with the forks… Obviously the Pro Circuit A -kit cartridges are better with bump absorption, small chop/big bumps, is excellent on hard landings, as well as slap down landings. The best feature of the A-kit is the traction, lean angles on sweepers,  lean angle on hard braking, traction under hard braking in braking bumps is excellent and allows you to charge most situations. However my question was how will the stock forks stack up? The stockers were actually closer than I originally thought. They soak up hard landings/slap downs, big bump absorption is great as is small bump absorption and I still feel confident charging into braking bumps. The only areas where the A-kit performs better is when I am looking for traction while in sweepers and hard braking. So the question is what is the best bang for your buck? That depends on your situation, but the A- kit is better due to simply better internal technology/tolerances and if you're a serious racer, it’s definitely worth the money. If not, the PC stock re-valve  is still a very good option that will allow you to push the green bike’s limits and still be comfortable.

The previous shock that PC did was just a tad on the stiff side on that initial part of the stroke, which if I was able to ride faster would have probably been fine, but at my age and unwillingness to hit the ground, I have my limits. With that being said I look for comfort and predictability, probably just like you. The revised setting kept the character that I liked with the stock shock and improved it in the areas that it lacked. Initial hold up was improved, but kept that small initial area of plushness allowing the shock to absorb the small bumps and not squat too much ending up too far into the stroke and become harsh. This also eliminated the wallow feel in g-outs and rollers, improved big bump absorption and harsh landings were handled with ease. I purposely flat landed off a couple jumps and was really impressed on how well it absorbed the impact. Overall, I'm really happy with this suspension package because I am now in that comfort zone that keeps me from going crazy when I am trying to push it.

If you’re looking to get your KX450 suspension done, are near my weight (190 lbs.) and want this setting, you can reference this article to the Pro Circuit guys. They can get you dialed in with what we came up with.

When I rode this bike with the stock exhaust I remember having a controlled, connected feel with the power. The throttle had that connected feel to the rear wheel, the power felt seamless and my corner speed was really good through all areas (1,2,3) of each corner. After exiting is where I felt the stock power needed a little more pulling power. Initially I went with the full Ti-6 system from PC and it produced the results I was looking for. It helped the KX450’s power from initial crack of the throttle and up through the mid to top end. If not for a conversation I had with a friend on how I was liking the bike, I would have never tried the slip on version that PC offers for this bike. I was happy with the power output, but just wished I could move it around where I needed it most. He suggested the slip on muffler with the stock header, so I said why not.

The slip on brought back the feel I was missing, but still produced a little better mid to top pull than the stock version. The stock header is longer, which produces a smoother yet responsive power that is easier to control for me. The Ti-6 header is shorter which produces a snappier feel, but also can be harder to control on harder surfaces. The two slightly different power bands and power deliveries can work at different tracks, so just make sure you know what you’re looking for before purchasing. If you're like me and grew up on two-strokes you may still have that style of hitting the throttle hard and clutching the bike more than you should. I've adapted to the four-stroke style of riding for the most part, but there is still a part of me that gets a little “two-stroke” when I am pushing hard. That being said, I found the stock header with the PC slip-on allowed me to still ride that way (even though Keefer tells me not to) and allowed me to stay in control yet carry more corner speed. I can tell you that "feel" I was missing was found again and I believe it's a combination of the power delivery of the stock head pipe and PC slip on coupled with the revised shock settings. On entering turns the bump absorption and calmness of the shock matched with slightly more engine brake feel from the longer head pipe that allowed me to carry more roll speed on the initial part of the corner. Once through area 1 of the corner, the transitioning into rolling the gas on through area 2 and 3 provided me with the controlled power delivery that makes the KX450 stick better through shallow ruts. 

Additionally the delivery allowed the chassis to feel more calm through acceleration chop and produce increased comfort and traction I was missing. It boils down to preference, what suits your riding style and what is your end goal. When I was younger and racing more, I would have preferred the shorter head pipe with the snappier power. These days when I'm  looking for more comfort and predictability I like the characteristic of the slip on and longer head pipe. So remember when you get a little off track with your settings and struggle, try to reset, make small tweaks and I think you'll find you were closer than you thought. I wanted to write this article to give you a few more options to try just in case you were searching for something more after your 2020 KX450 honeymoon phase. We will be trying a couple more modifications to this Kawasaki KX450 in the coming weeks so stay tuned to keeferinctesting.com to see what I have in store. 

Testing Terms Explained (Suspension/Chassis)

Since we are in some weird times right now with this quarantine stuff, I thought it could be cool to learn a little about what each testing term means. What better way to get more in tune with your motorcycle than learning what the definition is to each term. If you listen to the Keefer Tested Podcast or read anything here on keeferinctesting.com you will hear/see these testing terms being used. Some of you have emailed me and asked what the hell some of these terms mean, so below is your template on what each means. Hopefully you can use these to your advantage next time you are talking about your machine or need to get a certain point across to your suspension/chassis tuner.  

Pitching: This word is used when the rider lets off the throttle and the weight of the motorcycle forces the front end down. This usually happens when there is a lot of engine braking or the fork is too soft. The 2018 YZ450F was notorious for having a lot of this pitching when coming into a corner. Pitching can upset the chassis balance and can cause some oversteer through area 1 and 2 of corners. Pitching can also mean that a certain bike can squat (shock) too much under throttle out of corners causing the bike to have too much movement fore and aft. Pitching can make the machine seem unstable and cause the rider to not set up properly for corners. 

Hold Up: Hold up is mostly used when the fork or shock is riding too low in the stroke. When a rider is asking for more hold up he is usually wanting a stiffer compression setting so the fork or shock isn't “blowing through”. 

Harsh: This term has got to be the worst feeling to a rider. A harsh feeling is when the suspension is either too soft or too stiff. Yes, it can actually be both! If the suspension is too stiff the rider will complain about a harsh or firm feel through the handlebars. This stiff/harsh feel is caused by the suspension not being able to use all of its stroke. If the harsh feel is coming from the stiff side, opening the compression or the rebound can help alleviate some of this feeling. If the harsh feeling is coming from a soft sensation it’s because the suspension is riding too low in the stroke. Riding too low in the stroke can cause a harsh feeling because you are now in the mid stroke where the valving starts to ramp up to get stiffer. By stiffening the suspension a little you are now stiffening the initial part of the stroke which can actually make your bike feel plusher because your machine is riding higher up in the stroke around the track. “Harsh” is a tricky term because the cause of the harsh feeling can be from a too soft or too stiff of a setting.

Plush: I have never been a huge fan of this term, but the word plush means soft or supple feeling. If I hit something at speed most riders want their bike to feel plush and not harsh. However be careful when using this term to suspension techs as they may want to set your suspension up too soft. Plush can also mean the same with frame feel. For example, the KX450 has a plusher feeling to its frame than the of the Honda CRF450R. I like to use the term “bump absorption” more than the word plush. When the Kawasaki KX450 hits a certain square edge at speed, it has a better bump absorption feel than the Honda CRF450R. Off-road riders look for that plush feeling because they have less jumps to deal with and can hit roots/bumps at higher speeds. A softer compression setting or a faster rebound setting usually leads to a plusher feel.

Crust: We can thank air forks for this term. I came up with this term when I was at home during thanksgiving and I was watching my wife make a french apple pie. I always liked the middle of the pie more than the crust, so it immediately made me think of air forks. In order to get to the gooey goodness of the pie, I have to break through the crust right? Well air forks are the same thing! The top of the stroke of almost any air fork is called the crust because it’s usually has a hard/harsh feel initially and then you have some comfort. The crust usually gives you some deflection and a harsh feeling through the handlebars on small chop. We use the word crust because air forks usually feel like you have to break through the stiff portion of the travel in order to get to the softer/more forgiving portion of the stroke. WP has improved the air fork feel over the years so let's hope they continue down the path of a less crusty initial stroke on their air forks.  

Empty: This term can be used when talking about engine character or suspension feel. When talking suspension empty usually means there is not a lot of damping feel. If you say “I feel like my end stroke is empty”, it means that it blows through or simply doesn't have any damping feel. 

Rigidity Balance: Rigidity balance is an important term when testing any chassis. If the bike has a firm feel and its rigidity balance is too firm it could mean that it corners excellent, but feels very harsh and has deflection on rough/fast straights. If the rigidity balance is too soft the bike can have a wallow feeling when under throttle as well as give the rider less confidence on braking bumps because of its unpredictable feel. Rigidity balance is something that every manufacturer works a lot on when developing their machine. A bike has to corner with precision, but also have enough comfort in order to have good bump absorption. A machine that has great rigidity balance is a Kawasaki KX450 because it turns well and can hit bumps at speed with a consistent feel.   

Performance: Performance is a word we used in the testing world when a rider is looking to ride at a higher level as well as be able to push the motorcycle without having it be too soft. Getting a chassis or suspension package to have better performance is basically asking the tuner that you understand that you’ll sacrifice some comfort, in order to get a machine that you can slam into obstacles harder without getting blow through. Usually riders that are faster or heavier want a performance based setting so they can hit jumps as well as bumps at a faster rate. 

Comfort: A comfort setting is something most vet riders want so they don’t feel every little bump on the track. A comfort setting usually involves a softer setting that moves more in the stroke, but also can bottom out when hitting bigger jumps or larger bumps at speed. The 2020 YZ450F’s suspension package is a great example of blending both performance and comfort together. 

Blow Through: This usually happens when hitting bumps/jumps hard and the suspension just dives without much damping force feel. If your suspension feels like it’s blowing through then you need to try and get a stiffer setting through clickers or internally with valving.  

Vague: Vague is usually a term used by describing front wheel traction. Front wheel lean angle traction can feel vague when the fork setting is too stiff, have the wrong offset triple clamps, or if you have the wrong compound front tire. A vague feel means that you will be washing your front tire out under lean angle and the bike may have less of a contact patch. Running too much air in your tire can also give you a vague feel.

Damping Feel: Damping feel or force is the feeling of the suspension when moving down. Damping feel is used when explaining to tuners that you either have a soft feeling and need more of a stiffer setting. Damping feel can also be helpful/used when asked if the action of the suspension is too fast or too slow. 

Deflection: Deflection happens when either a suspension setting is too stiff or a chassis setting is too rigid. Deflection happens when your front or rear end hits a bump/square edge and your bike simply doesn't absorb it. It’s like a pinball bouncing around from some side to side and can cause you to roll the throttle off in a hurry. Deflection also causes you to have less contact patch and makes the bike feel less planted. Going to a softer setting with the suspension or chassis usually alleviates some of this feeling. 

Contact Patch: Contact patch is a feeling of how much tire is felt underneath you. Contact patch can be increased by running less air pressure in your tires, running a softer suspension setting, chassis setting and/or increasing/decreasing offset. I like using this term a lot with my evaluations because without the feeling of a wide contact patch it will feel like you are running bicycle tires on your dirt bike. Having a wide contact patch feel gives you more confidence to roll the throttle on sooner when exiting corners.