Reving

[TeamBlue250]

so i rebuilt my 02' yz 250 motor with a new crank, seals and bearings and all new seals for the whole motor. and i finally go it runnign but it revs up all the way by its self. anyone have any suggestions.

[Wacko Jacko]

your sucking air from somewhere i bet
pretty sure a bad crank seal can cause this? dont quote me on that though

[climb any hill]

A leakdown test would rule out the crank seal leaks! Definately start there since it's a fresh build!
Tool Forum shows a good inexpensive Leakdown Tester.

[02yamahablaster]

Did you check and see if your slide in your carb is stuck?

[SHOWTIME]

Originally Posted by climb any hill

A leakdown test would rule out the crank seal leaks! Definately start there since it's a fresh build!
Tool Forum shows a good inexpensive Leakdown Tester.

That would be my recommendation
as well. You can get them for a
descent price. Would definately save
alot of time and frustration...

[TeamBlue250]

yea i thought it might be in the carb some where. i checked the base gasket which was still good. i turn the screw on the car out and it still did it. maybe the trottle is stuck?

[MADILL]

look in from the air filter...how hi is it???a frayed thortal cable will hold it up ...but more likly a crank seal or some seal...suckin air .....

[TeamBlue250]

after i turned out the screw it was normal un til i hit the throttle

[02yamahablaster]

Your slides sticking, pull the cap and check it out.

[TeamBlue250]

yea once it gets a bit warmer i will check it out thanks everyone!!!!