Hi, i currently adjusting my atv valve because of the excessive valve noise. I have purchased the shop manual and on the shop manual the valve clearance say intake 0.06 to 0.10mm and 0.16 to 0.20mm exhaust (engine cold). Remove my fuel tank and the valve cover set the engine at tdc, set the intake at 0.08mm and the exhaust at 020. I start the engine, the noise are gone for now, I run the bike for about 10 minute, the valve noise is start and get very loud, it seam to be from the intake I do not allow the engine to get cooler and check the clearance it is 0.15mm intake and 0.20mm exhaust. Let it cool for 3 hour; recheck the clearance and it is 0.08m intake and 0.20mm exhaust. The intake lash over 0.07mm as the engine get hot, this is probably what causing the valve noise when the engine hot?? Should I tighten my intake valve??? Please help me, thank Christ!

 

no one know much more about valve clearance

 

I have never heard of altering clearances based on measuring them hot. Do you have stock springs and cam, because that can make a big difference. The YFM350 motor has always made a little more noise up there than most motors. I would make sure you have the retaining nuts tightened down well and go from there. Just to be sure, you are feeling a slight resistance on the feeler gauge when you check it, right?

 

everything is done right ! the locknut was tighten with torque wrench at 20 nm !

 

usually valves will tighten up as things get hot and expand so I dont know what is going on to cause it to loosen up when it gets warm.

 

i had the same problem with my warrior and come to find out my timing chain streched. so i changed the timing chain and it went away. that was about 5 months ago and i haven't had any problems since.

i'm thinking this could be your problem. if your valve clearence is right then i would check the timing chain. before you set the motor at TDC see if you can move the timing chain (slack) then set it to TDC and recheck if there's still play or more play than before TDC you have a streched timing chain.