I just rebult my 87 250x now for some reason it won't run. I put new valves. new cam shaft and rocker arms in. Anyway I was pop starting it cause I got sick of trying to kick it over but when it got started it would not rev up and it would stall when I let out the clutch. or stoped moving. I think the only reason it was running was because I was getting a tow to pop start it and keeping it moving was the only thing turning it over. If anyone could maybe help me with any ideas I would be most grateful thanks.

 

your timeing marks right? check that first then with piston top dead center on compresion stoke set valves at .004 gap with feeler guage to tell if on compresion stroke valve rockers should be slightly loose if not turn one more time tell timeing marks aline again you want the T mark not the F i use ratchet against foot peg to keep engine from rolling past mark remove plug during this makes alot easyer. now dont ride bike to hard tell you past 15 hour break in time after that you may have to readjust valves. any more ? id be glade to help been in your shoes many times.p.s. dont kill your self tring to make it start it aint going to start no faster by kicking the crap out of it. if it dont start right away after a couple kicks try something new trouble shoot it check spark check gas to see if getting any is plug wet or dry if it hasnt started plug should be wet if not you got a fuel problem if plug is wet could be spark problem if back fires and pops spits sputters (timeing off or valves out of adjustment)never ever over tighten you valves better to have little tap in valves then none. Ride safe