66 A65 leaking oil onto chain.

A friend is looking at a 66 BSA chopper. The owner says the gear oil onto the chain and was told the cases will need to be split to fix this oil seal. But the owner is not very mechanically oriented and knows nothing about his bike. We haven't had a chance to look at it to determine. My question is if it is the main seal or gearbox seal can't they be replaced by pulling off the inner primary cover and or timing side cover? Thanks.

Should be able to pull the primary cover, pull the primary drive/clutch, remove the access door, remove drive sprocket, and change the seal.

Thanks Paul that's what I told them too. I haven't had a chance to go look at a book but I know I can get to the seals. Not sure why his mechanic told him the case it's needed to be split. Now I'm thinking maybe it never had the bearing conversion done and might need it. A 66 probably has that bushing in the timing side and needs the conversion to a bearing.

The bearing conversion is such an expense that the person who had it done would certainly pass on to subsequent buyers that it had been done to the bike.

Some shops stamp engines that they've overhauled or modified; I stamp "BAB" on the large pad below the timing cover on Commandos I've overhauled.

Yeah the problem is the owner barely understands anything mechanical and knows nothing about British motorcycles. Any information passed to him would've been for not and lost at this point anyway. My friend wants to buy the bike as it is regardless so I guess I will be learning to work on a BSA twin soon. Can't be too much different than my BSA 441 shooting star.