What Gasket Goo ???

[Greg65]

I thought a T140 that wasn’t leaking had no oil in it?

[Bryanj]

You two are heathens, i was with a dealer selling new T140V from Meriden, sold dozens and non leaked plus only had 1 warrantee claim for a holed piston where the owner "adjusted" the points gap, thats when i found there were 2 different 750's with different bores, oopsie. That  was also oil tight when i rebuilt it

[royhall]

I rebuilt mine in 1982 and went to great trouble stopping leaks. I even scraped the joints with a surface plate and blue. All good gaskets, seals, etc and checked all the shafts with a magnifying glass for micro damage. All that stayed oil tight but still had a few drops of oil coming out. On close inspection it was coming out of the crankcase casting just above the scavenge pickup. A porous sand casting, the bloody thing was sweating oil, and I wasn't the only one with that trouble. I gave up after that and it was decades before I had another British bike.