We need help on this. We pulled the manual starter cover off and removed the black plastic plug so that we could see the timing marks. We also pulled the three covers that conseal the 5 valves (3 intake, 2 exhaust).

What we need to know:
1. What exactly does the valve clearance need to be for the Intake and Exhaust valves?

2. How do we know when we are exactly TDC on the compression stroke so that we can check for proper clearance?

3. Do we adjust when we are cold or warm??

4. What is the compression supposed to be???

We did all of the following checks and adjustments when the quad was cold. When we first checked for valve clearance, there was NOT any clearance. We are not sure if we have adjusted for the proper clearance (Intake .004-.006", Exhaust .005-.007"). We adjusted for what we thought was TDC on the compression stroke and now we are getting backfires when the throttle is applied. For TDC, we rotated the flywheel until there was no action on the both rocker arms (full up position) and we passed the "H" looking stamps and came to the single tick. We didn't have backfires before this adjustment.

We are not sure if we have done something wrong or not. This ATV has about 1200 miles and the valves have never been adjusted. The original sympton was that is was hard to start. Now, it starts just like when it was new, except for the backfires. The unit will also die as soon as you apply the throttle coupled with the backfire.

We can also apply partial choke and apply throttle, and it won't stall now, but it still wants to backfire.

I'm sure this has been asked before, but we've searched through the archives and just want to get current information.

Thanks,
Tom

 

Usually the easy way to find out which top youre at, is to wiggle the rockers. Both should be loose, and if they arent, then youre at the top of the exhaust stroke. Spin the crank another 360, and try wiggling again. If you adjusted at the wrong tdc, youre gonna need to redo it.
Backfires usally mean lean, or valve timing. Were you running with the air box lid off? that would make it lean. If not, youre gonna need to redo the valve adjustment.
heres a generic article on valve adjusting

valve adjust
Sorry,, but i dont have the specs on the clearances, i know ive seen it on here before, do a search . try here,
thread

 

1) I adjust my raptor at .005 int. and .007 exh.

2) Turn the engine over counter clockwise and watch for the intakes to open ( go down) then close ( come back up) it's about another half a turn after that. You don't NEED to be EXACTLY on the marks.

3) Cold

4) I'm guessing about 165 or so.