Belt Deflection (Tension)
Belt deflection is very critical for proper clutch performance. If your deflection is too tight, the belt will burn on the clutch hub and you will lose top end. If the belt is too loose, it will allow the primary clutch to upshift faster then the secondary clutch causing a low end bog and poor performance.
To check your belt deflection
You will need a straight edge and a tape measure. Normally you want your belt to stick out of the secondary clutch 1/16" - 1/8" if possible.
Lay a straight edge on the belt and measure the distance between the straight edge and the belt between the two clutches. Lightly press down on the belt to remove any slack.
Most machines use a spec of 1 1/8" to 1 1/4" of belt deflection. If you measure less than 1 1/8", your belt is too tight. If you measure more than 1 1/4" your belt is too loose. This procedure should be shown in your owners or service manual.
Factory specs are: Polaris 1 1/4", Arctic Cat 1 1/8"-1 1/4", and Ski-Doo 1 1/4".
Look at your manuals to see how to adjust belt deflection. Anytime you change your belt, your deflection can change. Remember, when you put on a new belt, it will stretch after awhile and the deflection will need to be reset.
Adjusting belt fit
Most clutch systems allow adjustment for belt fit. This is usually accomplished by adjusting the secondary pulley halves spacing -- either with shims or mechanical adjustment mechanisms. Center distance adjustment can correct some fit problems but should only be done as a last resort. This can lead to misalignment between the primary and secondary pulleys, drastically reducing belt life. Additionally, center distance adjustments should only be made within the tolerances specified by the sled manufacturer.
Always adjust for the highest ride possible in the secondary pulley to get the best low gear possible, but avoid tightening so much that belt has difficulty de-clutching. This also can cause excessive wear on the bottom of the belt.
Many belt fit problems can be traced to a severely worn belt . Normaly, top-width wear in excess of 1/8 inch is too much.