I've not had this problem myself (yet) but i've just put my crankcases back together and i had a look at the internal castings of the crank case halves to try to get my head around how the oil pump gets 2T into the oil feed holes of the crank main bearings. I also had a look to see if there was a way for gearbox oil to get into the crankcase somehow if a seal failed. I just ended up confusing myself really...

It might be getting through the 2T galleries from inside the clutch housing - i'm not sure which seals are responsible for preventing this though. Those two little rubber O-rings that go behind the oil pump drive gear are the only ones i can think of.

Another unlikely possibility is that gearbox oil is getting pulled past the clutch side crank seal when there is negative pressure in the crankcase on a compression/exhaust stroke.

You at Manfeild this weekend mate?
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