It's a bead roller. Usually they have different dies to swap out for rolling in different shaped beads/ribs/joggles etc. I too have one, handy piece of kit if you're doing sheet work restoring cars etc.

As above, they are to set the end float of the selector shaft. I didn't require them in mine, nor were any removed before I fitted the new bushes (but the old bushes were heavily worn!). Simply put, you really want as little end float as you can get away with without it binding up when hot or even when the inner cover is tightened - with little to no end float all the motion imparted by the cams is used to move the forks and the selector dogs rather than moving the selector shaft. The excess endfloat on my selector shaft, coupled with a worn fork and groove caused 3rd gear to drop in and out of mesh - it's worth getting right!

How long ago are we talking? I would think the only way would be through any club(s) or friends who knew them and the bike. I assume you know the registration mark?

Well Calum at least you’ve found the problem. I must confess that I drilled out the apertures on all those bolts on my B31 as 1/64th seemed to me to be too easy to clog up with a bit of debris. I did open up the lower ones more so. I haven’t found it to flood with oil yet or smoke. If it does smoke more as time passes I’ll renew the rocker box ones, they are easy to get to.
Pete

I don't suppose it's likely to flood the top as long as the drain holes are considerably larger than the combined area of the supply banjo orifices. I'll remove the drain pipe and drill the bottom banjo out to match the top and see how we get on.

Have you had the head rebuilt. Sounds like wear on the valve guides. Oil in the head sucked into the engine down the side of the inlet valve.

Nope, never had the head off. There's no smoke on the overrun or going down long hills to speak of so I don't think the guides are too bad. I do have some jobs planned for the engine in the future but for now I am just enjoying riding it when I can. Once I finally build my new garage I suspect I will spend a lot more time tinkering...

Does the short go away if you back the centre bolt off ever so slightly? It screws into a nut which I believe is encased in plastic/resin to insulate it from the mag body. If this screw is overtightened I believe it can crack the plastic and short across. I only ask about backing it off slightly as a test as I found I had a similar issue on my mag, although with the locktab folded over it did run fine. I couldn't get my head around what was touching where.
I bought one of those timing lights but off someone else on eBay, a little cheaper than the one from 'the magneto guys' but both would be a worthy investment. Very helpful in my diagnosis work on my bike.

Mine on my '53 B31 is just like the drawing from the manual above. It slides into the clips in the bowl, and the glass lens is held in from the inside by a spring wire pushing it up against the rubber seal.

I rebuilt my plunger B31 box recently and I bought a box for spares (many for the good selector forks) but I did end up using a gear or two out of it. It was stamped M20 on the casing but came disassembled so I can't guarantee it was all correct. I'm pretty sure the gear ratios were identical.

Hi all

I have been very much enjoying my first summer of BSA ownership. 1953 B31. The gearbox rebuild proved very successful, and the mag rebuild has all but cured my hot running and starting issues. I've just returned from a 420 mile round trip to Suffolk this weekend and the bike never missed a beat. However one problem which seems to be slowly getting worse is the smoking...

It doesn't smoke from cold. It doesn't smoke when under load, nor when on the overrun. But when the engine is hot and I come to a stop at traffic lights or a roundabout it begins to emit a lot of smoke out of the exhaust! It doesn't always do this however, and I haven't worked out of there is a pattern to when it does and doesn't. As I pull away the smoke very soon clears.

My initial thoughts are the top end flooding with oil, and/or the return side of the pump not being able to pump the oil back quick enough after fast running. Oil consumption is generally quite good, so I don't think the rings or the valve guides are too bad; I also think this would cause a constant haze when moving along, but I am open to any suggestions at all!