2001 kx 250 starts up in full rpm

[deker234]

i bought a 01 kx 250 today knowing it hadproblems, when you start the bike the rpms go throught the roof, okay, so i turn the fuel screw down, rpm's go down a little but still eratic at times, i start to think it must be a fuel issue. i check the pilot and main jet finding nothing and then the needle and seat, still finding no problem. my question is, if the powervalves are stuck wide open will this cause the bike to run at full rpms? is there a way to check the powe valves without taking off the head? am i chasing the wrong problem? i am new to this forum so any advive would be appreciated

[KickassKX125]

It takes about 15 kicks to start my 125 up it revs through the roof for about a 10 seconds and then takes its self back down to idle, it takes about 20 seconds to come back to idle. But after that as long as its warm it will start 1st kick and shoot off the moment you get into the powerband.

I don't think its anything to do with the powervalves, but if you wnt to check take the linkage cover off, I dont know where it is on the newer style engines but on mine its on the R/H side of the barrel.

Its more likely to be carb related.

[stevied645]

Or lefthand crankseal related if its blown it revs sky high and doesnt come back down, the only other reasons could be sticky throttle cable or carb boot has a hole in it, if carb boot is fine and the slide in the carb is fully shut then it will prob be the crankseal, do a leakdown test

[SBC383STROKER]

The powervalves is not your problem. You have an air leak somewhere after the carburetor. Since you said it was a 2001, the air boot is old and fatigued and therefore may have craks on it therefore causing your motor to lean out and then rev to the moon. The other reason is you might have a worn out ignition side seal, again, causing your to run lean and have erractic revs.