Well, this time my problem is it appears my engine is leaking oil. Its coming from the crank-case, yet all the seals are good, and no screws are loose.
I cant tell exactly where its coming from, because even after cleaning it and running it maybe a minute or two, the bottom of the case is covered in bluish-grey oil.

Dood,


I believe this is your engine:



It feeds on a mix that contains plenty of oil and has a shielded front bearing (i.e. not sealed)...
It should leak some oil; especially if it has a rather loose fit of the crankshaft in the crankcase (tolerances accumulate)...


I don't see it as a problem, but if it ever becomes one; you can replace that front bearing with a double contact-sealed version of the same size.

It should be a 10x19x5mm 6800-2RS bearing, which should have a C3 clearance.

I know what engine i use :P Thanks anyway though. I thought it was time to replace the bearings.

Byodood,

Feel how the bearings turn. It can be normal for a good engine to have oil seep through the front bearings. It can be messy, but those seals aren't perfect.

Is it coming from the exhaust? The fit between the manifold and the crankcase might be loose, or if the gasket is on its way out it'll leak

There should be plenty of fuel and oil mist coming from the carb venturi as the sonic wave from the rotery valve causes negative pulses. This is normal and can only be controlled with a velocity stack, or filter. Even then there may be some oil.