1998 Yamaha Warrior engine knock
 

My Warrior engine has a knock that seems to originate from the bottom end. Compression is at 140PSI and it seems to start and run as normal. Are there any common issues with these that i should look for?

1998 Yamaha Warrior engine knock
 

Check the oil.

1998 Yamaha Warrior engine knock
 

That's the first thing i checked.

1998 Yamaha Warrior engine knock
 

Put a socket on the crank and turn it by hand against the compression back and forth. If you hear a knock or tap, then the problem is piston slap.

Also, if the knock is louder when it is cold, then it is most likely piston slap. It may be time for a fresh top end.

I wouldn't think that the low end would make noise. Usually, that's solid unless yiou ran it out of oil.

1998 Yamaha Warrior engine knock
 

I puloled the motor out and began disassembly. I have not pulled the cases apart yet, however, everything turns nice and smoothly with no noticable crank or rod play. The cylinder is std. bore and measures at 3.265. Piston is good but ring gaps are in excess of .020. the only thing i found that could cause a knock is that the clutch basket had a lot of play and can be rocked back and fourth. I don't know if this is normal of not. Any suggestions? Should i go ahead and split the case. Valves were adjusted within reason and timing chain is ok. HELP!!!!!

1998 Yamaha Warrior engine knock
 

I figured it out. Looks like the piston pin is loose on the rod.