Primary chain case seal B31

[Kernowpete2]

Not having a lot of luck with sealing the primary chain case on my B31. It has the pressed steel chain case. I've replaced the cork gasket and put a bit of compound on one side so it's effectively glued to the outer cover and comes away with it when removed. I'm thinking about a making a gasket out of a different material e.g. neoprene foam sheet.
Anyone been successful trying something like this?
I don't want to seal it up fully with silicone as I tend to be in and out of there quite often playing with the clutch etc. so I would prefer the cases to seperate easily and not need old sealant to be scraped off and reapplied every time.

[yellow B31]

I may have been lucky with mine But I fitted a new cork gasket with a light covering of grease. When  replacing the cover screws I only nip them up, not loose but definitely not tight. After a 1000 miles still has its oil in it.
Never fill to the level plug, just enough oil for the chain to become wet when kicked over.

[martinh10]

Totally agree with the above response to your query. Are you sure it's coming from your chaincase? I had quite a bit coming out from between the gearbox mainshaft and the pinion sleeve (which carries the sprocket) and running down the chaincase. I stopped this using an 'O' ring on the mainshaft pushed onto the end of the pinion sleeve.
On another occasion my engine had wet sumped so much it drained into the chaincase and chucked oil everywhere.

[Kernowpete2]

Thanks people. Yes, sure it's the chain case. I've been all over it multiple times to check. What leaks is engine oil as it's darker than gearbox oil. I think the engine may be breathing a bit heavy and getting oil mist into the chain case. It's not wet sumping. I use the bike pretty much every day, never see the tank level drop between rides etc. I did think it may be oil from the vent on the inner chain case but I lost some clean oil overnight after refilling through the chaincase gasket. Other than this and the odd drop out of the crankcase breather the bike is pretty oil tight.

[cdsdorset2]

Try 2 different dyes in the oil to be certain. I remember on a forum somewhere that they used foam draught excluder pretty sucessfully.

[Kernowpete2]

I think I'll order some foam sheet and go from there. I've exhaustively investigated the source of the leak over several weeks.

[V500]

Did you dress the screw holes in the covers before refitting? After 70 years of ham-fisted tightening many are distorted around the screw holes.