i am new to this, sorry if something does get screwed up! i have owned the machine for awhile now and have done quite abit of work to it; front diff, carb, bearings etc. so i know the machine fairly well, so i think... all the problems i have had i have fixed myself expect this damn knock in the top end!! the knock comes and goes. i have reset the valves twice but the knock is still there... i am now thinking it could be the cam chain?? i need someone that knows these machines inside and out that can help!