Ben1992250

Member
Apr 21, 2009
2
0
I have a 2003 yz 125 and i just started to noticed that when i take off and go threw all the gears floored, that when i pulling in the clutch and come to a complete stop my bike is idling really high like im holding the throttle a quarter of the way open. But when i take back off in first and go a foot and stop again my bike goes back to idling fine. I also put a new piston and rings in my bike recently and it did not change anything. I adjusted the air screw alot but it didn't change the high revving at an idle after riding my bike floored. What could the problem be?
 

sharky243

Member
Dec 14, 2008
246
0
Sounds like an air leak to me. Possibly crank seals or a broken gasket somewhere. Do a vacuum test on the crankcase, this will find the leak.
 

sharky243

Member
Dec 14, 2008
246
0
Remove the pipe, and block the exhaust port. Remove the carb., and block the intake. Make an adaptor tool from a broken sparkplug so that you can connect a peice of hose to the top end of the spark plug shell. Take an automotive type vacuum hand pump and connect it to the hose. Apply 5-10 inches of vacuum to the crankcase and watch the gauge on the vacuum pump. If the gauge goes back to zero, you have a leak. If it holds the vacuum, the crankcase is air tight and good.
 
Top Bottom