I have a 98 polaris 400l sport. while riding last weekend. i heard and felt a loud and not normal noise. it happened when i hit the gas real hard and then i hear a loud clunk like something was not engaging then all of the sudden it does. It does not happen all of the time. but i know that it is not normal. could the belt be going bad. or what? any suggestions would be helpful.

98 400l sport
hpd clutch kit
hpd performance exhaust

 

Start simple. I would check the bushings in the drive clutch, make sure it works smoothly in and out. What ever you do do not try to lube the clutch with WD40, etc. If you need to clean the clutches buy a clutch cleaner. Usually it is a fast drying silicone. If a bushing is missing it would cause the clutch to bind and then once rpm's get high enough it would slap. If it is not in the clutching ask your local Polaris mechanic. I'm just a parts guy so I can give you some simple things to check but I don't want to go around stating how to tear down a tranny. Good luck.

 

Check your belt and Primary Clutch.

 

Also check to be sure the rear swingarm is tight, especially on the right side. If it is loose, the power sent through the chain has a tendency to 'yank' on the swingarm, making it 'clunk' at the bushing. Lift the rear end up & set the skid plate on blocks (or use a floor jack) so the rear swingarm hangs free. Grab the rear wheels & see if there is any wiggle where the front of the swingarm hinges on the frame. There should be very little or better yet, no play. It can be hard to find sometimes as you hear the 'clunk' just as the clutch grabs, and it sounds like it could be in or by the engine/tranny.