oil in my crankcase?

[Cory9584]

I just picked up an old rm 125 that needs a top end and noticed the crankcase has about an inch of mucky oil in it. I don't know how it got there, too much oil in the mix over time? or maybe the last owner poured it in there to try to free the piston from the rusty cylinder. Whats safe to use to clean the crankcase out?

 

[Matt90GT]

more than likely from a leaking petcock and needle valve.

I would suspect the crank and bearings are rusted out. Time to change them to.

 

[Cory9584]

I ended up dumping some mix in there, then dumping it out. It came nice and clean. The bearings feel good so i'll let that go. The needle theory sounds like it may be right, the sludge smelled like gas and the tank was completely empty. I'll have to check that.

 

[rmc_olderthandirt]

If gas made if from the tank to the crankcase then there is probably another issue that needs to be addressed. A stuck/leaky float should result in gas dripping out onto the ground, not into the engine. This might be something as simple as the vent line was routed "UP" instead of down but you should make sure that there isn't something else that provided a flow path into the crankcase

Rod