Before you even begin to tackle the tough job of dialing in suspension, you need to know what type of riding you will be doing. Whether its trail, MX, TT, desert, or woods racing, proper suspension will make you faster or allow you to ride longer with out getting tired. After you have decided which type of riding is most important to you, you can start to set up your quad's suspension to best suit you weight, ability, and the terrain.
When setting up your suspension a good place to start are at the A-arms and swing arm. There are lots of good (over priced) aftermarket brands to choose from, but the real decision is what width A-arms and length swing arm do you need. Your probably wondering what wider A-arms do, and do I need? At most racing events there is a set width limit that your quad can be(usually 50''). They measure the quad from out side of your front wheels. In MX, TT, and desert you want to be at the limit, because the wider the front is the less roll you will have, and it also creates more control and stable ride. But if you are riding XC or trails that have trees, you are going to need shorter or stock length A-arms so that your quad will be able to fit between the narrow areas that the trees create.
The swing arm is also a major part in setting up your suspension. A longer swing arm from 1 to 2 inches longer will give you better straight-line stability but will take away traction under acceleration. A shorter swing arm is good for TT racing or hard packed, slick MX track. You would use the longer swing arm if you have plenty of traction and especially if you race desert or off road, where you need straight-line stability.
The wider aftermarket A-arms and a longer swing arm also create a better controlled suspension travel and more adjust ability. When purchasing wider A-arms it will be recommended that you replace your standard shocks to help the performance of your quad. Reason being is the geometry and shock mounting points of the new a-arms will not work with a stock length shock. The A-arm and swing arm manufactures will also recommend the length and travel shocks that are right for you and your quad.
What is Next
First start wit the ride height (sag) of your quad. This measurement is taken on flat ground, with the rider in full gear sitting on the bike in normal position. It is very important that the rider always sits in the in the same spot on the bike while taking the ride height, or each time you check it will be different. Also try to have about the same amount of gas in the tank. Now measure from the ground to the bottom of the frame, either in front or behind the foot pegs. Just make sure you measure it from the same spot every time. To raise the ride height you will need to tighten the spring pre-load adjuster to put more tension on the spring. To lower the ride height you will need to loosen the spring pre-load adjuster.
Most manufactures have different ways to do this. Some have a threaded collar (or large thin nut) that you can twist to increase or decrease pre-load. Some have a whire clip that slides into groves in the shock body. Here you would raise or lower the clip into a groove to make the adjustment. No matter which is used, the job is much easier if the quad is jacked up and the shocks are free of dirt.
Setting the Ride Height
TT racing - 4-6 inches
MX - 6-8 inches
Trail riding - 7-10 inches
Desert - 8-11 inches
If the track or course that you are on is smooth with out big jumps, you want your quad low to the ground, so that the quad can turn well. But when the quad is low it will not take jumps or bumps as well. If the track is rely rough, then raise the quad up so that it can handle those conditions.
There has to be a balance between turning the quad and handling the track. 1 inch of ride height change can make a difference. This is something you need to experiment with. You should bottom lightly at least once each lap on the track or else your not using the full travel of your shock. You don't want to bottom hard though which that will wear out parts faster and you.
The rest of the article can be found here How to Set Up Your Suspension - LT-R450Central - #1 Source for the Suzuki LT-R450 - TheATVChannel