Suspension Tuning Guides

[ousley99]

Here is an article I found on the Kaw forum. The guy's info is at the bottom of the article. Thought some of you might be interested:

Suspension Tuning Guide

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Suspension Tuning Guide

Street Bike or Road Racing Applications

With incorrect suspension setup, tire wear is increased and handling suffers,

resulting in rider fatigue. Lap times can be dramatically slower and overall

safety for both street and race enthusiasts is another issue. Add the

frustration factor and it just makes sense to properly setup your suspension.

The following guide will help you dial in your suspension for faster and safer

riding both on and off the track.

Basic Setup: Check the following

Forks sag 25-40 mm

Shock sag 25-35 mm

Check chain alignment. If not correct, bike will crab walk and sprocket wear

will be increased.

Proper tire balance and pressure. If out of balance, there will be vibration and

headshake.

Steering head bearings and torque specifications, if too loose, there will be

head shake at high speeds.

Front-end alignment. Check wheel alignment with triple clamps. If out of

alignment, fork geometry will be incorrect and steering will suffer.

Crash damage, check for proper frame geometry.

Adjustment Locations on Forks

Rebound adjustment (if applicable) is located near the top of the fork.

Compression adjustment (if applicable) is located near the bottom of the fork.

Spring preload adjustment (if applicable) is generally hex style and located at

the top of the fork.

FRONT FORKS:

Forks: Lack of Rebound

Symptoms:

Forks are plush, but increasing speed causes loss of control and traction

The motorcycle wallows and tends to run wide exiting the turn causing fading

traction and loss of control.

When taking a corner a speed, you experience front-end chatter, loss of traction

and control.

Aggressive input at speed lessons control and chassis attitude suffers.

Front end fails to recover after aggressive input over bumpy surfaces.

Solution:

Insufficient rebound. Increase rebound "gradually" until control and traction

are optimized and chatter is gone.

Forks: Too Much Rebound

Symptoms:

Front end feels locked up resulting in harsh ride.

Suspension packs in and fails to return, giving a harsh ride. Typically after

the first bump, the bike will skip over subsequent bumps and want to tuck the

front.

With acceleration, the front end will tank slap or shake violently due to lack

of front wheel tire contact.

Solution:

Too much rebound. Decrease rebound "gradually" until control and traction are

optimized.

Forks: Lack of Compression

Symptoms:

Front-end dives severely, sometimes bottoming out over heavy bumps or during

aggressive breaking.

Front feels soft or vague similar to lack of rebound.

When bottoming, a clunk is heard. This is due to reaching the bottom of fork

travel.

Solution:

Insufficient compression. Increase "gradually" until control and traction are

optimized.

Forks: Too Much Compression

Symptom:

Front end rides high through the corners, causing the bike to steer wide. It

should maintain the pre-determined sag, which will allow the steering geometry

to remain constant.

Solution:

Decrease compression "gradually" until bike neither bottoms or rides high.

Symptom:

Front end chatters or shakes entering turns. This is due to incorrect oil height

and/or too much low speed compression damping.

Solution:

First, verify that oil height is correct. If correct, then decrease compression

"gradually" until chattering and shaking ceases.

Symptom:

Bumps and ripples are felt directly in the triple clamps and through the

chassis. This causes the front wheel to bounce over bumps.

Solution:

Decrease compression "gradually" until control is regained.

Symptom:

Ride is generally hard, and gets even harder when braking or entering turns.

Solution:

Decrease compression "gradually" until control is regained.

REAR SHOCK:

Adjustment Locations on Shocks

Rebound adjustment (if applicable) is located at the bottom of the shock.

Compression adjustment (if applicable) is located on the reservoir. Spring

prelude is located at the top of the shock.

Shock: Lack of Rebound

Symptoms:

The ride will feel soft or vague and as speed increases, the rear end will want

to wallow and/or weave over bumpy surfaces and traction suffers.

Loss of traction will cause rear end to pogo or chatter due to shock returning

too fast on exiting a corner.

Solution:

Insufficient rebound: Increase rebound until wallowing and weaving disappears

and control and traction are optimized.

Shock: Too Much Rebound

Symptoms:

Ride is harsh, suspension control is limited and traction is lost.

Rear end will pack in, forcing the bike wide in corners, due to rear squat. It

will slow steering because front end is riding high.

When rear end packs in, tires generally will overheat and will skip over bumps.

When chopping throttle, rear end will tend to skip or hop on entries.

Solution:

Too much rebound. Decrease rebound "gradually" until harsh ride is gone and

traction is regained. Decrease rebound to keep rear end from packing.

Shock: Lack of Compression

Symptoms:

The bike will not turn in entering a turn.

With bottoming, control and traction are lost.

With excessive rear end squat, when accelerating out of corners, the bike will

tend to steer wide.

Solution:

Insufficient compression. Increase compression "gradually until traction and

control is optimized and/or excessive rear end squat is gone.

Shock: Too Much Compression

Symptoms:

Ride is harsh, but not as bad as too much rebound. As speed increases, so does

harshness.

There is very little rear end squat. This will cause loss of traction/sliding.

Tire will overheat.

Rear end will want to kick when going over medium to large bumps.

Solution:

Decrease compression until harshness is gone. Decrease compression until sliding

stops and traction is regained.

Stock Tuning Limitations

The factories plan on designing a bike that works moderately well for a large

section of riders and usages. To accomplish this as economically as possible,

manufacturers install valving with very small venturis. These are then matched

to a very basic shim stack which creates a damping curve for the given

suspension component. At slower speeds this design can work moderately well, but

at higher speeds, when the suspension must react more quickly, the suspension

will not flow enough oil, and will experience hydraulic lock. With hydraulic

lock, the fork and/or shock cannot dampen correctly and handling suffers. The

solution is to re-valve the active components to gain a proper damping curve. It

does not matter what components you have, (Ohlins, Fox, KYB, Showa), matching

them to your intended use and weight will vastly improve their action.

Furthermore, if you can achieve the damping curve that is needed, it does not

matter what brand name is on the component. Often with stock components, when

you turn the adjusters full in or out, you do not notice a difference. In part,

this is due to the fact that the manufacturer has put the damping curve in an

area outside of your ideal range. Also, because the valves have such small

venturis, the adjuster change makes very little difference. After re-valving,

the adjusters will be brought into play, and when you make an adjustment, you

will be able to notice that it affects the way the way the fork or shock

performs.

Another problem with stock suspension is the springs that are used. Often they

are progressive, increasing the spring rate with increased compression distance.

This means that the valving is correct for only one part of the spring's travel,

all other is compromise. If the factory does install a straight-rate spring, it

is rarely the correct rate for the weight of the rider with gear. The solution

is to install a straight-rate spring that matches the valving for the combined

weight of the bike, rider and gear to the type of riding intended.

Remember

Always make small adjustments, more is not always better.

Always keep notes.

Suspension tuning is an art, be patient. I hope you all find this helpful. Feel

free to email your questions to us at info@mototechnw.com. We are always happy

to help inprove your ride. Herb Varin

__________________

beansbaxter.com is my blog

[natedogg624]

good article!

the chart below works as well for those that want a quick flow chart although the above is more detailed

http://i10.photobucket.com/albums/a149/natedogg624/SuspensionTroubleshooting.jpg

[serpentracer]

I'd like to remind everyone, you cannot go using someone elses setup and think that is going to work for you. this is why so many guys have it way off.

if you don't know what you are adjusting and what it affects, let someone that does do it for you. without the right understanding you aren't going to get it right.

if you want a good visual of the suspension setup watch this video

http://www.onthethrottle.com/content/view/73/40/