['First off there was no cork sleeve seal behind the clutch. Maybe this why I had clutch slip and oil in the clutch...']...
That was probably not the issue...About 25 years ago (or more) I had one of the corks sleeves break up...I didn't have a replacement at the time and just reaassembled it all without one...No problems and I've never fitted one since...
It appears you have the wrong inner chaincase...I think it's off a C10/C11/C11G etc...There are many versions of the tin chaincases for different models..Check the part number in the M20 parts list...When looking for a replacement you will find the part number stamped into the casing just above the hole where the garbox mainshaft comes through, at about 1 O'clock when your looking at the inside of the case....Ian
Was a bit surprised I don't need Cork sleeve behind clutch I suppose that should be good news in some ways. However, oil has been getting in the clutch but maybe not so much from this direction. The domed clutch cover gasket was very poor so maybe that's where the oil got in.
As noted elsewhere this bike is a bit of a mongrel with a few odd parts. I thing even the gearbox is not standard, as although not used, it has a speedo drive coming out of the casing and 3/8" final drive chain. So... tempted to leave the chain case as is. After al, it fits fine and looks ok.
