HELP!! I just rebuild my 250R motor (new piston & reeds) and now I can not keep it running. It will start every time but it dies after a few seconds. The motor will not idle or run at anything below 4,000 rpm after it starts. I can have the throttle in any position and it does not affect the motor. I have taken the carb apart and it looks good. Is this an air leak in the motor?

Thank you for any help!

 

The same thing just happened to my buddy's Tecate 250, it would start, run for about 15 seconds and then die no matter what the throttle position was, I think we cleaned out the carb five times and it didn't help. He finally went to the local shop and they said it was wet-fouling the plug, the ceramic was soaked with fuel even though it looked clean and had spark outside the cylinder, inside the spark was extinguished by the fuel and then grounded to the inside of the plug. He bought a hotter plug that was a little longer and now it fires on the second kick and runs every time.