Hi all.
Still trying to get my B31 on the road, currently changing fluids. I'm onto the primary chain case but not sure it's the correct one for the B31 as the manuals I have refer to a simple one with a screw for the drain and level where I appear to have a more "advanced" cover!? See picture.
There is a bolt in the front face (drain?), large brass round plate with a bolt head in the centre (filler?), is there a level indicator?
Many thanks, Ian.
This may help.
The large screw cover is for filling and checking the primary chain adjustment.
Photo from Pitmans "The Book of the BSA"
The drain should be underneath on the back section. It looks like the level plug behind the brake lever. Is the hole where the brass plug is located very large as it could be an WD M20 case.
What year is your B31?
Thanks for all the replies guys. That diagram looks about right, I'll take a proper look at the bike tonight.
I'll have to check the V5 for the year but it isn't necessarily correct. My dad bought the bike in the early 1980s and it was an absolute wreck. Even the number plates were so rusty that the number couldn't be identified so he was given a new age related reg from DVLA. So what I'm getting to is I believe the bike is probably made from whatever my dad could source from rummaging through auto jumbles over 20 years!
That said, the attached picture that I found on-line is very similar to what I have but says that it is a B33. Can anyone enlighten me as to what the differences were between the B31 and B33?
Cheers all!
Ian
B33 has a larger cylinder bore, slightly larger clutch, more clutch plates. Different gearing and possibly an 8 inch front brake. B31 had a 7 inch. Don't know why as they weigh the same. Most likely to justify the price difference.
if your gearbox looks like the one in the picture then it should be a 1946-48 model. The later ones had more screws on the forward half holding the outer cover on.
B31 = 350cc, B33= 500cc
Quote from: Pete C on 20 Dec, 2021, 13:06
if your gearbox looks like the one in the picture then it should be a 1946-48 model. The later ones had more screws on the forward half holding the outer cover on.
The timing cover is later though although that could have been changed at any time.