Motorcycle & Sportbike Suspension Adjustment Inofrmation

There are three possible adjustments on the front and rear suspension of a motorcycle: spring preload, compression damping, rebound damping. The 94 VFR might not have all of these adjustments on front and rear.

Spring preload sets the initial "stiffness" of the spring. Damping keeps the bike from behaving like an old Cadillac - i.e., still bouncing 10 seconds after hitting a bump. Compression damping slows the shock when it is being compressed. Rebound damping slows the shock when it is rebounding. How about that?

Set the preload on each end so that the bike settles 1/3 of its total travel -- look in your owner's manual for total suspension travel. This ("sag") is measured between (a) the wheel suspended off the ground, and (b) you on the bike with all applicable gear, luggage, passenger, etc. If the forks do not have adjustable preload, set it by using a different length spacer at the top of the fork -- longer for more preload, shorter for less. PVC pipe works well.

You can increase the spring *rate* on the forks by cutting off some of the coils and replacing them with an equivalent length of spacer.

Use less sag for smooth roads and fast riding (e.g. CLASS), say 25%.

On shock absorbers: get the sag/preload right before messing with the damping. Start at the shock manufacturer's recommendations. Only change one setting at a time, and don't change damping more than 2 clicks at a time. For compression damping, increase until expansion joints or sharp bumps are jarring, then back off one click. Don't forget that when you increase preload, you have to increase rebound damping (and vice versa for decreasing preload).

Front suspension symptoms, likely causes, & possible
Solutions:

Symptoms: Not using full travel, feels harsh, poor traction in bumpy corners Causes: Overly stiff springing or compression damping
Solutions: Lower air pressure; reduce compression damping; softer coil springs

Symptoms: Bottoms, soft throughout travel Causes: Spring rate too low throughout travel, or too little compression damping
Solutions: More air pressure; increase compression damping; stiffer coil springs

Symptoms: Bottoms, but compliant over small bumps Causes: Spring rate not progressive enough
Solutions: Raise oil level

Symptoms: Harsh over large bumps, but good over small ones Causes: Spring rate too progressive
Solutions: Lower oil level

Symptoms: Excessive sack, feels soft initially but doesn't bottom Causes: Initial spring rate or preload too low; springing too progressive
Solutions: Add air pressure *and* lower oil level; increase spring preload

Symptoms: Harsh over small bumps but uses full travel Causes: Initial spring rate or preload too high, springing not progressive enough, or too much compression damping
Solutions: Raise oil level *and* lower air pressure or install softer springs; reduce compression damping; reduce spring preload

Symptoms: Takes first bump in a series well but harsh over later bumps, poor traction in washboard corners Causes: Too much rebound damping
Solutions: Use thinner fork oil (or decrease rebound damping if adjustable)

Symptoms: Front end springs back too quickly after bumps, poor traction in bumpy corners Causes: Not enough rebound damping
Solutions: Use thicker fork oil (or increase rebound damping if adjustable)

Rear suspension symptoms & causes:

Symptom: Not using full travel, feels harsh, poor traction accelerating out of bumpy corners
Cause: Overly stiff springing or compression damping, possibly too much preload

Symptom: Bottoms, feels soft throughout travel
Cause: Spring rate or compression damping too low

Symptom: Bottoms, feels harsh, sinks far into travel with rider aboard
Cause: Too little preload, perhaps combined with too soft spring

Symptom: Wheel chatters over small bumps during braking or downhills. Doesn't hook up accelerating out of washboard turns
Cause: Too much preload (perhaps because of soft springs) causing suspension to top out; possibly too much compression damping

Symptom: Kicks over large square edge bumps, but not over large rolling bumps
Cause: Too much compression damping.

Symptom: Kicks over rolling bumps and square edge bumps
Cause: Too little rebound damping.

Symptom: Rear end takes first bump in a series but is harsh on later bumps. Poor traction out of bumpy turns or braking on washboard
Cause: Too much rebound damping.

Symptom: Back end extremely springy and shock doesn't respond to adjustments
Cause: Damping is gone because of low nitrogen pressure, tired oil, or damaged internal components.

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