I have a scrambler 400 and during accelleration there is a clunking noise and as soon as I let off it stops sounds like a skipping chain but thats not it any help?

 

i had a wee bit of a reck on saturday, snapped my thomb piece off my throttle and had the same thing going on. a clunk clunk clunk.

theres a plastic piece on the bottom of th wing arm that keeps the chain in place. the bolt on mine came loose so that this pice was able to wiggle around. I tightened it down and now the noise is gone. ghive this a try. its a simply fix and hopefully your problem.