Here is some stuff I have found
Compression Damping:
The Theory:
http://www.sportrider.com/tech/146_9608_tech/index.html (This is for road bikes however I still found it helpful)
It makes sense that the more compression damping, the more resistance to bottoming (refer to the curve). It may seem obvious, but you need enough, yet not too much. The compression damping force is added to the spring forces to resist bottoming. At the same time the bottoming resistance increases, the feeling of plushness decreases. (The decrease in plushness with minimal damping occurs when the suspension has bottomed out)
If there is too little compression damping, the wheel will not meet enough resistance as it compresses the fork or shock spring. Not enough energy has been dissipated at the crest of the bump. Because the wheel itself has mass and the mass is moving upward, it wants to remain in motion and continues to move upward, compressing more than the amount required to handle the bump. This means the tire will unweight and possibly even lose contact with the ground as it crests the bump. This unweighting produces a loss of traction.
As compression damping is increased, this phenomenon decreases and traction improves. If there is excessive compression damping, there will be too much resistance to movement and the wheel will not move the entire height of the bump. This means the center of gravity of the motorcycle (the sprung mass) will be displaced upward. Not only can this be the cause of an uncomfortable or harsh ride, but this upward velocity of the chassis will tend to unweight the wheel, losing traction.
Maximum dynamic dive is the amount the suspension compresses when hitting bumps or under braking. For example, under braking the front end will dive. More compression damping allows the chassis to dive less. The maximum amount of travel used is determined by a combination of the spring forces and the compression damping force.
More damping means the forks will compress more slowly and not as much.
Less damping means the forks will compress more quickly and more.
The Diagnosis:
http://www.bikesetup.com/compression%20damping.htm
How do you know if you have too much compression damping? If you are riding along and when you hit a bump and it feels like somebody just hit your bars or seat with a hammer, if you find your tires cup faster than your buddies, your bike seems to skip along with bumps ,or you find your bike chattering, you have too much compression damping.
How do you know if you have too little Compression Damping? There are a bunch of ways: if you are using too much travel, you have tons of chassis pitch, your tire comes off the ground on the upstroke. One symptom is that when your bike isn't "neutral" as in: you have to keep pushing on the bar after the initial input (as though it is pushing back). A few things could make this feeling (low pressure in the tire being one, but when you think about it, low tire pressure is kinda like having too little compression damping) but my first guess would be to stiffen the compression damping a click or two.
The Solution:
http://dirtbike.off-road.com/dirtbike/a ... ?id=264361
Rear shock: Increasing your compression damping (the screw on the shock reservoir), will slow down the compression stroke and decrease rear end bottoming. Turn you compression adjuster "in" (clockwise) to reduce bottoming. If you never bottom, try turning your adjuster "out" (counter clockwise) to soften the compression damping and use more travel. Slight occasional bottoming is OK, but don't allow the bike to crash down when bottoming.
Front Forks: Increase the compression damping (the screw at the bottom of the forks) to slow the compression stroke and decrease front end bottoming. Turn your compression adjuster "in" (clockwise) to reduce bottoming. If you never bottom, try turning the adjuster "out" to soften the compression damping and use more travel.
Rebound Damping:
The Theory:
http://www.sportrider.com/tech/146_9604_tech/index.html
The major trade-offs involve traction, a feeling of control and plushness. If you look at the graph you'll see they're all plotted on the same graph. There are no numbers on the y axis because these are largely subjective quantities. In other words, we are discussing "feelings."
You will notice that traction starts out at a low amount at very light (quick) rebound damping settings, increases to a maximum, then decreases again. Why? At very light rebound settings, the chassis is uncontrolled. When the wheel hits a bump the shock is compressed. Then the wheel extends without any control; in fact, it extends too far. Because the sprung weight of the chassis has mass and is moving upward, it wants to pull the wheel off the ground, thereby losing traction.
If you direct your attention to the right side of the traction versus rebound damping curve, you will note that at high rebound damping, traction has suffered. This is due to the wheel not being able to follow the ground simply because it can't respond quickly enough. The suspension compresses as it hits a bump. Then, it can't follow the ground (return to its original position in the travel) fast enough after the crest of the bump to maintain traction. When this is excessive it is called "packing." Somewhere between these two rebound damping extremes, traction is at maximum.
You may have noted from your own riding experience that when rebound damping is very light, the feeling of control is minimized. The bike "feels loose." As you increase rebound damping, the feeling of control increases. The chassis isn't moving around nearly as much and the bike feels more "planted" and stable. When rebound damping is very slow, meaning there's a lot of damping, traction is so poor that the feeling of control suffers as well. Once again, somewhere between the two extremes the feeling of control is maximized.
The third quantity is plushness. At very light rebound damping, the wheel moves very quickly and the feeling is plush and mushy. As rebound damping is increased, there is more and more resistance to movement, and at maximum damping the wheel is "packing" so much, the chassis is sucked down in its travel and has not recovered for the next bump. This means the following bump has to overcome the added spring force due to this compression and the result is a jolt to the chassis upon impact.
The key thing to note here is that there is a trade-off. As you can see, maximum traction does not necessarily occur at the same damping setting as maximum feeling of control. Herein lies a problem.
Quite often riders have mistaken ideas about how much damping should be used. They think the faster they are (or the faster they want to be), the more damping they need. Nothing could be further from the truth. In fact, after a certain point, traction, control and ride quality (plushness) are all sacrificed
The job of suspension engineer and suspension tuner is to make these two peaks-traction and the feeling of control-as close to the same point as possible.
The Diagnosis:
http://www.bikesetup.com/rebound%20damping.htm
Tankslappers can happen because of too much rebound damping in the fork. This is the chain of events: the tire hits a bump and goes up but is not returned fast enough to the ground for the second bump, without any weight on the tire for the second bump, the tire gets bounced, maybe to one side, and that starts an oscillation, and boopty boopty boo and your into a full on tankslapper.
Wheelspin. Another drawback to having too much rebound damping is that you get more wheelspin because as the tire is slowly lowered to the ground, the grip is too gradual and it starts to spin, and once spinning it is easy to keep on spinning.
The Solution:
http://dirtbike.off-road.com/dirtbike/a ... ?id=264361
If either front or rear tends to kick up, (rebound), more than the other after landing from a large jump, then more rebound damping is needed at that end.
http://www.bikesetup.com/rebound%20damping.htm
My rule of thumb when it comes to any form of damping: use as little as possible, let the springs do the work!
If you find that your rear end "comes around" or gets "squirrelly" under hard braking, you probably have too much rebound damping in the shock.The problem is that the tire is not returning to the ground so it is just skipping along the high spots in the road.
Spring Rate
The Theory:
http://www.strappe.com/suspension.html#rate
Spring rate is the actual amount the spring compresses when a set load is put on it.
Another thing to keep in mind with springs, the stiffer the spring, the more force gets directed upwards because of the increased resistance, so if the spring is stiffer than required the force will not get entirely soaked up by the springs
The Solution:
An increase in spring rate of 10% is substantial.
An increase in spring rate causes springs to compress less
A decrease in spring rate causes springs to compress more
Preload
The theory:
http://www.bikesetup.com/
Preload is just how much pressure you load on to the spring before the actual load of the bike and rider is applied
Springs like to work best when they are under a little pressure.And straight rate (constant rate) springs will sag under the load of the machine and rider, taking up travel. And if you hit a bump you will take up further travel. To fix all this we use preload.
When we preload the spring, we already pressurize the spring so we take up less travel to hold the bike and rider up,plus the spring works better because it is already under pressure.The common misconception is that by bumping up the preload you make your spring stiffer
The Solution:
Increasing the preload on your rear spring will decrease the Race sag. This will raise the rear of your bike putting more weight on the front wheel and reduce the front-end rake. This will always make the bike turn sharper. However, if you tighten the spring too far it will make the bike twitchy and promote headshake.
Decreasing the preload on the rear spring will increase the Race sag. This will lower the rear of your bike, putting less weight on the front wheel and causing it to ride like a "chopper". This will reduce head shake, making the bike go straighter and be more secure in high speed sections. However, if you loosen the spring too far the bike will be harder to turn.
Info needed - Fork Spring preload
Some more road bike info - http://www.ntnoa.org/suspension_preload.htm
Oil Level
The Theory:
http://www.strappe.com/suspension.html#level
The fork oil's primary function is to be pushed through small holes to damp the rebound of the spring.
In a bike fork there is the spring, the oil, and the trapped air above the oil.
This air is important - air, when compressed, acts like a spring, but with a rising rate. That is, the more it's compressed the more force it takes to compress it a bit more. Most fork springs, on the other hand, are linear (straight rate).
The idea is to set the oil level so that the right amount of air is trapped to keep the forks from solid metal contact at full compression. (Obviously, bottoming the fork internals leads to a harsh ride and component damage.) The right amount of oil will allow nearly all of the fork travel to be used in riding and stopping.
The Solution:
If the working travel is too little, remove a bit of oil.
If it's near or equal to the max, add some.
Well thats it for now. By the way I didn't type any of that, I just took the best bits out of the websites I found. If you have any other tips please post them and If a mod opens this thread I will add them to the main post. Also a lot of the websites I quoted were for road bikes, I presumed the information would be fairly similar. If anything is incorrect please correct me.
