New member first BSA

[SamNorwich69]

My first BSA

[Rog1]

A nice pre-unit single. Is it a B31 or a B33?

[SamNorwich69]

B33 , new to BSA and pre unit bikes,it's leaking oil badly I guess it's either the sump plate or primary drive ,is this an easy fix

[Jean-Luc]

Nice bike.
Strange front brake for a B33 though.

[idie]

It looks like a B31 7 inch front brake. 60s

[Jean-Luc]

Picture quality is poor.

[Rog1]

B33 , new to BSA and pre unit bikes,it's leaking oil badly I guess it's either the sump plate or primary drive ,is this an easy fix

Not too difficult. Check the nuts/screws/bolts on the sump plate and everywhere else, degrease everything, then go for a ride. I find that oil leaking from the engine very often ends up dripping off from the bottom of the primary cover, just under the clutch and looking like a primary case leak.

If you find the primary case is leaking then you need a new cork gasket and a couple of cork rings, for sealing the spacer that the footrest bar goes through. It's just a matter of removing the footrest (the bar goes all the way across the bike; there's a nut on each end) and about 18 casing screws. The screws are, or should be, all the same. On replacement, put just enough oil in to drip out of the level plug, so that oil doesn't get on the clutch.

But if the leak is that bad, more than a few spots on the ground after a ride, the breather might be gummed up. It's in the rear side of the timing cover, pointing back and down. In the breather there's a disc that goes back and forth, letting air out as the piston comes down, but preventing air being sucked in as the piston goes up.

Take out the breather, there's a pipe with a hole near the top. The hole should point to the right of the bike and slightly backwards when the breather is installed; mark the breather body with a permanent marker so you can see where the hole points when the breather is replaced. You might have to fiddle around with sealing washers to get it pointing where you want, maybe make some out of cardboard.