I recently replaced a broken cam chain and gear on this quad. I also adjusted the valves to be on the safe side.

Now here is the question/problem. I got the machine started and was at a very high idle but would still rev higher. After a few minutes of the very high idle the exhaust pipes became cherry red. I shut it down and let cool off and re-started, again it became cherry red.

I tweaked around on the carb a little bit and got it started again. But now it seems to use the fuel in the bowl and dies out.

What caused the pipes to become cherry red and now why is it dying out on it's own? What can be done to get this up and running? Also what is the main purpose of the pilot screw and could this be part of the problem?

 

Is the pipe cherry red hot while riding, or just when it sits there still at idle??? Hot ofen means a lean jetting condition.

The pilot jet sets the amount of fuel when the throtle is closed. Think of the fuel/air screw as the fine tuning for the pilot jet. Lots and lots of problem posts in here, that can be traced back to a pilot jet that got clogged up by modern fuel formulations.

 

Could be many things but my #1 guess is you have an air leak somewhere.
If the thing idles high without any adjustment of the idle screw you have an air leak somewhere. With a four stroke it is a lot easier to find. A two stroke can be a bioetch to find because they can suck air from so many area's. Check everything from the carb to the head.

My #2 guess would be you have the cam timing off or you have the valves misadjusted.

If it ran fine before the chain change then you screwed something up during the change.

Don't go making adjustments to things like the pilot jet if it ran fine before.

My call is you have an air leak and it's throwing the mixture way off. You might try spraying some WD40 around the carb boot and head and see what happens.

 

Checked the timing and it's TDC with the cam sproket marks.

Checked from carb to head and all was tight.

Next move is to maybe re-adjust the valves.