2015-16 CRF450R and Earlier Model Review

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2015 CRF450R Bikes in the garage and being tested at the track.
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2015 - 2016 Shock Adjuster
They foolishly tried to put the Rebound Adjuster at the reservoir with the Lo and High Speed Compression adjusters. It didn't work well. We have 2014 shock shafts in stock to return the rebound adjuster to the lower clevis where it belongs!


A review of 2015 - 2016 Rear Shock suspension changes:

 This is the first dirt bike shock that moves the Rebound Adjuster from the shock shaft to the Shock Reservoir. Technically this change is hugely different and even risky. Historically rebound adjustment is done by adjusting screw on the lower shaft clevis which advances a cam which moves an aluminum rod that opens and closes an orifice in the main shock piston. As the orifice is closed, the 'free' oil flow path through the hole is closed which forces the oil to flow through the piston. The increased flow resistance creates a larger pressure differential across the piston. The result of the pressure differential is a force. This force opposes the shaft motion which slows the motion. We call this a rebound 'damping' force.  NOTE: one of the little know features of this design is the aluminum rod inside the steel shock shaft. As the shock heats up, the aluminum rod expands faster than the steel shaft. This causes the rebound orifice to close as the shock heats up. This reduction in oil free flow helps to offset the effect of the hot oil becoming thinner. The end result is as the oil thins from heat, it is offset by a smaller bleed orifice and overall shock damping remains relatively constant.

The new Honda design does not adjust an orifice at the main shock piston for rebound changes. Instead the new adjuster assembly in the reservoir restricts the flow of oil back into the shock during the rebound stroke. By restricting the return flow of oil to the shock body, the oil pressure above the shock piston can be either increased or decreased. Thus the pressure differential across the piston can be increased or decreased which creates either more or less force resistance during the rebound stroke. This is clearly a novel approach to rebound damping adjustment. But I'm not sure that it offers an automatic orifice change as the oil heats up and thins out. Additionally the adjustment range may be less than what we had in the conventional shock piston orifice design. I will report back when I figure it out.

WITH ADDED TIME TESTING, I FIRMLY BELIEVE A NEW SHOCK SHAFT WITH INTEGRAL REBOUND ADJUSTER FROM A 2014 MODEL WILL DELIVER BETTER ADJUSTMENT and LESS REBOUND FADE. WE STOCK THIS SHAFT......

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A review of the 2015 - 2016 PS2 Fork suspension changes:

The fork is now a 'single chamber' air fork with a balance spring (No Twin Chamber). The compression and rebound changes have been moved to the top of the forks. The internal damping is the same inside each fork, but internal flow circuit changes cause one fork to adjust rebound while the other fork adjusts compression damping.  

 - The beauty of these forks is there is only one air pressure adjustment. Additionally this design builds up less pressure during a moto and doesn't affect late moto internal pressure rise as much as the 2013-2014.

 - The shortcoming is the single air chamber pressurizes the entire fork. If air pressure is lost the fork looses its ability to hold up the bike. As a secondary issue, the high pressure pushes the oil seal lips into the chrome tube creating stiction in the fork action. Additionally the array of adjustments gets confusing....

Testing: Our initial testing in October at Piru mx track illustrated performance issues and a severe shortcomings in the new shock.

    The shock has excess compression damping which is common in many of the modern MX suspensions. The symptoms of excess compression damping are great bottoming resistance, but the faster you ride the harsher the suspension feels. And the sharper the bumps, the less likely the rear wheel is to move fast enough to absorb the bump. This harshness is most likely to be noticed in high speed sharp edged stutter bumps that develop as the track develops and deteriorates. Too Tech has proprietary valving strategies that allow the suspension to 'blow off' on sharp edges while still having enough low speed damping for jump landings. We also ensure that the compression adjusters have enough range to adjust to soak up the Glen Helen downhill's or hit the large jumps at Milestone or Competitive Edge.

    On the rebound side of the shock performance, the testers/engineers 'simply failed to install enough rebound damping' in the shock. This omission was compounded by the new rebound adjusting concept which lacks the adjustment range of the conventional rebound adjuster concept. The lack of rebound damping is noticed in most rebound conditions. On jump landings the bike actually kicks sideways after almost any jump landing. The solution is actually quite simple and is accomplished by adding rebound damping. Our internal valving changes cause the adjuster to be positioned in the middle of the adjustment range. We do recommend using a 2014 shaft with integral rebound adjuster if budget allows.

As of November 10 we have had an opportunity to work on several 2015 CRF450R's with great success. While testing with the first customer who runs in the local Pro class, we offered to fine tune his revalve at our test track. His response was, "Don't touch it, it's perfect. I'll let you know if I need anything". (we haven't hard from him since.....)

2008 was the first year of the OEM steering damper (stock it did almost nothing BUT responds well to revalving.
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Update on the 2008 and 2009/2010 CRF450R
(Note: Large Reduction in Head Shake AFTER Steering Damper changes)
    FORKS - much stiffer than past years! Honda changed the front end geometry by adding 2mm of trail for 2008 and then added 3mm more trail for 2009. Apparently they felt they needed more fork compression damping with this geometry; but they went overboard by preloading the mid speed stack closed. This defeats the progressive characteristic of a mid speed valve stack by turning it into a low speed stack. For anyone but the most aggressive national Pro, the resulting lack of compliance needs correcting through revalving.
Unfortunately even with the best valving, the 08 - 10 CRF 450’s are prone too high-speed headshake (refer to my article on Fork Geometry and the hidden effect of “excess trail” for an explanation). Apparently Honda knew this and added a steering damper. I like the damper concept because the linkage design ensures progressive damping as the steering approaches extreme angles. The only flaw is that the damper does not possess enough damping to ‘kill’ the headshake after 1 cycle. The changes we make significantly increase damping and result in a HUGE reduction in headshake. The damper is so effective that it even minimizes headshake on a stock CRF 450R. I must admit that I was totally surprised by how much the revalved damper improves the CRF450R.

    SHOCK - 2008 similar to analysis below – harsh in the chop and kicks side to side.
                      2009 and 2010  KYB shock feels stiffer in the high speed chop than the 2008. In stock form the bike lacks high speed stability on rough tracks. We have found that lowering the rear end settles the chassis without affecting steering. Lowering through internal shaft shortening is included with each revalve to a 2009 and 2010 model for no extra charge. After lowering & re-valving, we find the 2009 rear end to offer the most straight line stability of the CRF line. Apparently the changes to the rear chassis was a good one.
CRF250R & CRF450R GENERAL OBSERVATIONS
CR suspension performance has come a long way since the first twin chamber fork and aluminum frame bike in 1997.  (Too Tech was really scrambling in 97 to tune the new Twin Chamber forks and develop a suspension that would work with the overly stiff frame.) We were the first company to understand and change the Internal Chamber (IC) springs in 1997. The tuning techniques developed for the stiff 1997 CR chassis are still applicable today (since the design of the twin chamber fork remains largely unchanged). 
Ideal rider weight for the 450F is 160 to 180 pounds while ideal weight for the 250F is 150 to 170 pounds. Heavier riders will usually feel their bikes are too soft! This is because the front & rear springs do not adequately support their body weight. The bike will dive too low in the front under braking and squat to low in the rear under acceleration. When the suspension compresses too far under braking and acceleration, there is not enough travel left to absorb the next bump. So even though the bike feels soft in most situations, it will become very stiff when it runs out of travel in rough terrain. CR suspension has used the same valving concepts since 2004, so all the bikes feel very similar.
The first step to proper bike set up is to install the correct springs.  Please visit my "Rear Spring Static Sag" page to check your rear spring rate or give me a call to discuss the optimum front and rear springs for your weight, riding terrain, and rider preferences. 
Once the proper springs are installed into your bike, it will then fit the 'ideal rider weight' evaluations discussed below.
General CRF 250 Riding impressions for the ideal rider weight of 150 to 170 pounds.
  • Front end rides high in the stroke, won’t dive into a corner, and feels harsh in square edges. Symptoms include jolts to your hands, arms, and shoulders along with difficulty initiating tight turns.
  • Rear end deflects when accelerating hard through acceleration bumps.  Tends to get knocked off course at high speeds or when slowing in braking bumps. Symptoms include being deflected off course when aiming for a rut or accelerating for a double jump. Trail riders will notice harshness and deflection when hitting rocks or tree roots.
  • Because the bike is small and light, many riders are happy with the handling and do not realize how much better the suspension could perform.
  • In the rolling bumps, big jumps, and well groomed tracks the bike should feel OK. Problems are accentuated by rough terrain.

Situation & Solution

The front fork valving is almost identical to the CRF450 except that it uses a 1.9 pressure spring instead of a 2.1.  The excess fork valving causes the front end to resist quick transitions, resist diving into turns, and provides too much feedback from the terrain - feels harsh.  Revalving the forks for more compliant action and reducing the pressure spring rate restores the plushness and promotes front-end turning and more dive.  For less aggressive riders and trail riders, we utilize multiple stages of compression valving to further increase plushness.
The rear shock valving has remained similar year to last year.  The stiff high-speed compression damping causes the rear to deflect of sharp bumps.  This is most noticeable when accelerating hard through the chop.  The rebound remains too fast near the top of the stroke and too slow at the bottom. The bike is either too lively on top or packs at the bottom depending on where the adjuster clicker is set.  Too Tech internal revalving includes a new rebound tuning strategy along with extensive adjuster modifications that relieve the high-speed compression kick.
For less aggressive riders in this weight group we recommend a lighter 5.0 rear and .44 front springs.  This is because less aggressive riders do not brake or accelerate as hard, so the chassis does not dive or squat enough to promote good handling. Lighter springs restore the correct balance of diving and squatting for this group of riders. 

General CRF450 Riding Impressions for riders weighing between 160 to 180 pounds

Very similar to the 250F except that the problems are amplified due to the increased weight and power. On smooth well groomed tracks the bike is a pleasure, but as the track roughens during the day the bike becomes harder to stay on line and the harshness tires out the rider
  • Front end rides high in the stroke and feels harsh in square edges. Tends to get knocked off course when trying to hit a precise line. Rider will tire out quickly. Symptoms include jolts to your hands, arms, and shoulders along with difficulty initiating tight turns. 
  • Rear end deflects when accelerating hard through acceleration bumps. (This becomes more noticeable after fixing the front end)  Symptoms include being deflected off course when aiming for a rut or accelerating for a double jump. Trail riders will notice harshness and deflection when hitting rocks or tree roots. Many riders think their shock is real good, but they do not realize how much the rear is affecting the performance of the bikes front ends.
  • In the rolling bumps, big jumps, and well groomed tracks the bike should feel OK. Problems are accentuated by rough terrain.
Situation & Solution
The front fork valving continues to get stiffened each year although the components have been the same since 2003.  This excess valving causes the front end to resist quick transitions and resist diving. Revalving the forks for more compliant action and reducing the pressure spring rate restores the plushness and promotes front-end turning and better dive.
 The rear shock valving remains similar year to year.  The stiff high-speed compression damping causes the rear to deflect off sharp acceleration or high-speed bumps yet may even feel like it wallows and rides low in rolling bumps (it is overly progressive).  The rebound remains too fast near the top of the stroke and if you turn the adjuster in to slow it down, the shock packs at full compression.  Too Tech revalving includes a new rebound valving along with extensive adjuster modifications and valve stack changes to produce a more linear compression valving rate.
 The forks have .46 or.47 kg/mm springs and the shock has a 5.4.  For hard charging riders the front spring rates are good for this 160 to 180 pound group.  Less aggressive riders may prefer .45 in the front.  Many lighter riders get static sag numbers over 1 ½” which indicates they can move down to a 5.2 rear spring for added comfort if desired.
Overall, the single most important change I make to the CRF suspension is to reduce the energy required to ride the bike. For a trail rider it means he is less exhausted at the end of the day. To a racer it means he can be as strong the last five minutes of the race as he was the first 15 minutes.
Please call me to discuss your specific complaints and needs to satisfy your expectations!

2003 CRF450R

The 2003 CR 450 suspension is improved over the 2002 model.  The shock action is very similar to the 02 except the initial ride height of the rear is taller.  This taller ride height keeps the rear up higher in the stroke and makes it turn better and feel like it has a stiffer shock spring in the rear.  By the way the shock spring rate is not stiffer this year like the magazines say.  It is the same as the 02 and equals about 5.3 kg/mm.  (Note: For 2002 models we have been lengthening the shock shaft all along.)

The 2003 CR 450 forks have dramatically different compression valving than the 2002.  For faster riders it is too soft and tends to blow through the travel on jump take offs and landings (low shaft speed valving).  At the same time the forks will feel stiff on sharp edges (high speed valving).  

The shock characteristics are similar to the front but not as pronounced.  The compression valving will make the bike wallow and feel soft (low shaft speed valving) in the rollers and feel stiff for many riders in the high speed chop exiting turns.  Shock rebound is too fast at the top of the stroke and/or too slow at the bottom.  If the rebound is adjusted properly to control rebound from full compression, the rear will pack and feel harsh in many parts of the track.  If the rear is sped up to follow the terrain and not pack, it will kick out sideways when you least expect it, especially on down hills.  

The interesting thing about the 03 is that many riders are confused because it bottoms in some sections but will feel harsh in others.  This classic complaint comes from a suspension which is too progressive.  (Not enough damping at slow shaft speeds and too much damping at high speeds.)

21 years of experience and twice weekly riding sessions provide the experience to successfully revalve this excellent bike.

Call me to discuss your particular complaints!

2002 CRF450R 
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