I suggest you don't focus on crankcase leakage at this point, Paul, until you gather more data on the engine. It needs to be run enough to understand what it is doing, with the field cleared of irrelevancies like whether the external bits (clutch, chain, chain lubrication and lubricant distribution, bar nose sprocket, chain brake, and so forth) are in trouble. Once we have a bare engine, either it gives a problem that should fit into a pattern, or it works like a charm and we know the problem lies in the bolt-on bits.
