here`s the story, my friend bought a 87 250x that was pretty clean. the owner said the motor was just gone through and that type of stuff. it seems to run good except a rattle in the topend. we adjusted the valves to .004 and it is still there. when we took the valve cover off there was no gasket, idont know if this has anything to do with it. the only thing ican really see to cause this is the decompression lever that goes into the valve cover(atleast thats what i think it is). any idea that you can give me i thank you for.

 

It could be a few things, but it sounds like a timing chain problem if your valve adjustments are correct.
Either the chain is worn or the tensioner that mounts to the cylinder is bad....or both.

The rocker cover does not use a gasket.

 

thanks knows alot, would it do much damage to ride it for a day, we are waiting for a clymer manual, it wont be here till next week. and is there anything we could do in the mean time. this sound kinda of comes and goes, its not in sync with the motor if you no what i mean. thank you.

 

I wouldn't ride it at all until the timing chain is found to not be the problem. If it breaks or derails, you could be looking for alot more problems.....broken piston, warped valve, bent rod, etc,etc

If it's not in sync with the engine, it's possible you could just have a loose fastener.

I would wait on the manual as a precaution. It would be a bummer to ride around for one week while waiting on a repair manual and then do more damage and have a parts bill twice as high as it could have been if you waited.

It's one of those things where you have to make your own call.