Is it a B40 lump?

[PeteRae]

Hi Folks,
Just easing myself back into BSA ownership as the big Jap multis are just too quick for me now!
Anyway, I have a pre OIF B25 frame with, what I believe to be, a 350 side points B40 engine. ( Serial Number 1973)
I've taken off the timing side cover as there was gearbox oil slowly seeping from the kickstart shaft when on the centre stand. When I removed the lowest fixing bolt it seemed to act as a drain from the gearbox...Is this right?
I've looked at the Haynes and Rupert Ratio's book and can find no mention of this drain bolt anywhere?
Also the only drain hole I can see on the inner case is about 1/8th diameter and located behind the kickstart quadrant.
Did BSA just drill these willy nilly or was there a set pattern?
There was some gear oil in the casing too so I'm guessing that it was maybe overfilled? Defo not engine oil.

Sorry for all the questions but I just want to make sure I've got the engine I think I've got??? 

Many thanks in advance,
Pete

[Mike40M]

On the B40 Mk1 (side point), which is the only B40 I have, according to the owners manual.
Drain plug under the gearbox pointing straight down.
Level plug between kickstart and gear lever.
Filler plug on top of gearbox.
Mine is stamped on engine with B40 GD xxxx, indicating it was a Danish military motorcycle.

[PeteRae]

Hi Mike,
Thanks for that.
The drain plug/level indicator on this is a plug underneath with a hollow pipe to indicate correct level.
The rest is as yours.
The thing I am most concerned about is the lower bolt in the casing which seems to go through both the outer and inner timing cases. Don't know if it's just a backup drain or someone has been over zealous with the allen keys and burst through the inner casing??
Oh, I've found the drain hole drilling in the inner casing...it was smeared with dirty grunge...jeez it's wee!!!
I assume from your description and from locating the hole that it is a B40 lump.
Thanks again,
Pete.