[Ace661]

I'm currently helping someone who overfilled the transmission on his 18 CRF150R. It was overfilled by approximately 1 qt. He said it ran for a few minutes but then locked up. After realizing the mistake, he drained the oil and put in the correct amount. This now unlocked the motor, however it will not restart.
Just looking for a few ideas on what could have happened, that I can pass along.

[JimDirt]

Welcome to the site !!

I would check the spark plug , most likely the oil got pushed up past the rings and coated the plug with oil ..... hopefully it did not damage the rings .... but my first thing I would do , is pull the spark plug and then turn over the engine with force , like you are trying to start it and see if oil comes out the plug hole , if so there are 2 things you can try .... first would be (with the gas tank removed still) crank over the engine till the majority of the oil dissipates ...... then replace the plug with a new one , re-install the tank , and try to start the engine using the cold start technique , and hopefully it will fire right up ...

The other more tedious attempt , would be , drain the remaining oil , with the plug out , (and the tank off) lay the bike upside down like you would a bicycle resting on the handlebars , and let it sit for a hour or so upside down so any residual oil will drain out the spark plug hole , try to angle the bike (raising the rear , etc.) so the plug hole is level with the ground , so ALL the oil in the cylinder will drain from it .... , you might also remove the exhaust and look to see if any oil is in it , if so you may have to repack the silencer if it is serviceable , then refill the engine (with the correct amount this time , then replace the plug with a new one , and re-install the tank , make sure the gas is flowing , and then try to restart the bike , as before mentioned most likely with the choke to prime the system with gas , which will also help wash away any residual oil that did not drain from the cylinder , and give the new plug a shot of gat in order to fire ..... hopefully it fires right up ...