so i did the valve adjustment, but when my quad is on it idle's rough and there is like a chattering noise coming from the engine, like something is hitting something. i rev it and the noise stops for a second then it starts again, but once its a little warm it stops all together. any ideas on what it is?

 

Could be the compression release is sticking . Were you sure you had it on the proper TDC?(top of compression and not top of exhaust)

 

i beleive it was tdc. is there a way to get it to stop sticking

 

so i went back over everything and everything was right, and yes i was in top of compression. but like i said it makes the noise when the engine is cold, it idles rough. once it warms up its the noise stops or if i press the throttle when its cold it stops for a second then starts again. Please help

 

Its hard to diagnose noise , over the internet. The 400ex isnt a quiet motor, and does make some noise. If you do a search, youll see this is a common complaint...sometimes its a worn out cam chain adjuster, or out of adjustment. Or it can be the decompressor sticking. Does the exhaust note change..from when the motor tics, to when it doesnt? Could it be an exhaust leak? I see you have an aftermarket pipe on it....it could have a small leak, which seals up, once the pipe gets hot and expands.
Did the tic first start after the valve adjustment?

 

is it true that sometimes the right hand exhuast valve gets stuck to the decompression release? i was reading something about that on another forum and it said that it can cuase an inaccurate valve clearance. juist curious.

 

the decompressor is supposed to only engage at 800 rpm or lower, so turning the crank by hand ( actually the socket and wrench), can make it engage. The step which is left out, in most guides on valve adjustments, is to move the crankshft bolt cw and ccw, rapidly a few times, once you find tdc, to ensure the decompressor isnt interferring.
You could try redoing the valve adjustment, and see if that makes for more clearance on the right side exhaust valve.

 

thanx i'll go try right now, and hopefully it works and i can go riding. its perfect dune weather today

 

ok so i think i figured it out. the idle speed was to low. i test rode it and it seemed fine. the noise stopped once i changed the idle speed. does that seem like a possible solution?