Hey guys, I have all of this posted under idling problems, I have a 03 300 arctic cat 4x4,
Done alot to it, have shop manual, trying to check valve clearance, but the manual does
not tell me how to find Top Dead center. How do I find TDC, and know for sure that's where I
need to be to check the valve with my feeler gauges??[img]i/expressions/face-icon-small-confused.gif[/img] Please help, any pros out
there this morning?

 

Odd the manual doesn't explain that... anyway, you only have to be sure you're not at TDC on the exhaust stroke, or anywhere but the base circle of the cam. The cam is pear shaped, with the top of the pear (nose of the cam) being the point at which the valve is held open. I'm not sure if you can see the cam on your quad or not, on mine you can't. What you need to do is rotate the engine slowly by hand and watch the valve you want to set. It will begin to move slowly downward as the cam pushes it open. As it begins to open, turn very slowly. Once it is fully open, the nose of the cam is holding the valve wide open. Now, where you want to be is exactly 360 degrees of crank rotation from this point, which guarantees the cam will be on the "base circle" and the valve can be set. So, place a wrench or power bar with socket on the end of the crank and turn it 360 degrees in the direction of rotation, and set that valve. If it's a single cylinder, you should be able to set both valves at the same point.
Another way to check is to remove the spark plug, and place a 12 inch piece of stiff wire (coat hanger straightened out) in the cylinder through the spark plug hole. Slowly turn the engine by hand back and forth to find the highest point the wire will rise to. This is TDC. To determine whether it it is TDC on the compression stroke, try checking the valve lash. If there is none, rotate 360 degrees and try again. When you are at TDC on compression, both valves should be closed fully, and will not move when you move the crank back and forth a bit. If they are "rocking" meaning that both intake and exhaust are moving, you are on the exhaust stroke. <u>Be careful with the wire that it does not become jammed between the piston and head, never turn the engine with the starter when doing this.</u>

 

Thanks Chilly, I'm about to print your info, head to the shop and start,
thanks for the quick reply, I have looked at other postings, and hopefully,
I can figure this out. Like I said, it's a great atv, and from what I have seen
on these forums, on the 250-300's, you just have to keep them checked, so
I have to learn how, because I won't pay the shop to do this all the time!

 

align the "T" line on the generator rotor with the index mark on the crackcase while keeping the camshaft drive chain pulled upward. Engage the chain on the cam spocket with the locating pin hole at just before top position. align the marks on the camshaft so they are parallel with the surface of the cylinder head