Greetings,

I have a '74 DT250 that had an injector pump seal failure and leaked oil into the crankcase.  This engine does not have a drain plug for the crankcase.  The engine is fresh-built, carb too with real Mikuni jets,  Good used pump installed and adjusted as per the factory book.  New points/condenser and timed per the book.

The engine starts easily and idles nicely - but when I wind it up, it begins to blubber and stumble around 4k and won;t rev past 5k or so.   The porcelane tip on the plug is nicely colored but the whole end is wet with clear oil.  My assumption is that there is a pool of oil in the bottom of the case.  As the revs rise, the increasing rush of intake charge picks up more and more oil from the pool until the charge will not ignite.

I will be grateful for all experienced opinions and practical advice.  At the moment, I can't see any way out of removing the motor, removing the top end, and turning it upside down overnight.

Sincerely,

Chris Finlayson
Existential Motorcycles
Alexander NC 28701