Hi all! About 50 hours on my 426 and after about 10 laps in the mud this weekend I began hearing a chain slapping noise from down below under hard acceleration and hard decelleration. Though it was maybe a rock wedged between the chain & guard/case, cleaned all the mud out & same sound. Left the ride (bumming too - 1st time on Broome/Tioga!) cleaned the bike up real good, started again - can hear a little slap in the engine at idle. Took cam chain tensioner off & it's working fine. Put back on & still noise. Noise seems to be coming from the cylinder area right infront of the front sproket. Before I tear into the poor old thing, has anybody heard of cam chain problems, or what this sound may be? It really sounds like a worn, loose drive chain - but within the engine. I appreciate any help, and am finding this board/page is making my day! Boz, 2000 YZ426, AMA #733256, Dist 3#805 And... if you ever get your bike up central NY area, stop by "Bozadilla" for a ride!