Leaking crankcase

You are half way there, might as well bite the bullet and lift the cases out and sort it.

Hmmm it won't be a good selling point leaking, but to fix it means the primary drive needs to come off and cases, timingside strip down, and replacing seals on something you have no interest in.....leave it and adjust the price to suit.

You would obviously need to tell any prospective buyer, and I'd suggest the price would be up to £1,000 lower for a bike with this known fault.

The primary drive (assuming pre-electric start) is no trouble to dismantle, neither is the timing side.

But it's your decision.

It would be a good idea to find out exactly where the oil is escaping. It might turn out to be from somewhere other than the crank case joint. Nortons have a stepped joint, making it far more likely to seal properly than a flat joint face, especially if it's never been apart - people do silly things like use a screwdriver in the joint to force cases apart. So have a good look

Paul

Is this the Commando with the breather on the back of the crankcase? I've just had this problem with a Commando 750. Until it wet sumped there was no, leak but as soon as most of the oil had drained into the sump it started dripping off the bottom of the crankcase. I traced this to a seepage from the union between the breather body and the crankcase. It is fiddly but possible to remove the breather whilst in situ. I did this and found that the gasket was falling apart. Replaced the gasket, reassembled it all and hey! no leak.