Hi,

Thanks to Tim Jeffrey I know have a 65-6279 rear brake arm (maroon) and thought I would share how much of a difference from the larger 42-6075 (black) there is. Basically the larger 42-6075 impacts the rear sprocket and doesnt fit. Draganfly say its an alternative but it doesnt work. Same with 67-6053 which doesnt work.

There doesnt appear to be any 65-6279's about and I was lucky to score this one, so will send off to SJ engineering to get some more made up.

Thanks
Hamish

Thanks for all the feedback.

I spent the weekend testing out the bike to see whats what. I would add that the 1955 Advert for the BSA M33 does states a top speed of 70mph.

I got the bike up to 58mph and it seemed pretty stable but I think it was a bit lumpy... i note that when slowing down it started to pop meaning that too much fuel is ending up in the exhaust. This could be a timing issue but I did also notice a small amount of soot in the exhaust pipe.

I know this will annoy some of you but I am running a premier carb 928 but I have to say that it does do a good job. I suspect that if I drop a main jet size - 3/4 throttle open, it might run less lumpy. I have a idle jet running a treat but I will need to play with the needle and main jet a bit more... perhaps try and run it a little leaner.

I have taken on board the comments on the gearbox and will focus on the engine tuning.

Hamish

Hi,

I have a 1955 BSA M33 Plunger. I am trying to workout how to get the most extra MPH out of the old girl. Its got a standard 4 speed gearbox that I rebuilt but didnt think about the internal ratios. Things can improve the speed include.

1. Larger engine sprocket
2. Smaller Gearbox Sprocket
3. Gearbox ratios.

Attached to this message is the 1955 BSA Sales Brochure with the gearbox ratios for both BSA B and BSA M, with and without side cars. Can someone explain how the gearbox ratios relate to the internal gears, number of teeth, and layshaft number of teeth etc. People advertise the 4 speed gearboxes as Goldstar's but may not have the right ratio's

Ideally someone out there will have a standard 4 speed gearbox with higher ratios that the one I have at the moment and might sell me them?

Thanks

That’s excellent! Indeed there are probably a fair number in the same position rubbing and damaging the plunger unit. It would be good to have an archive of such details for other restorers or part makers.

Hi,

See attachment.

Lucas E3LM magneto off a BSA M33 1955. Magneto rotation is clockwise. Amal Concentric 928 19cc idle, 106 Middle notch and 220 main jet - all advised by Amal for this bike. 20% general jet size when using concentric is their rule of thumb. In general no choke is required.

When slack cable - is this in an advanced position or a retarded position?

When I pull the cable via the lever and it tightens the cable am I advancing or retarding?

I am starting with Level pulled 50% of the way round. It starts first kick.

After warm it still runs faster with cable pulled - is this fully retarded meaning my mixture is too weak?

Thanks
Hamish

Hi,

Engine was professionally rebuilt by Chris Odling along with a fully reburb'd mag dyno. It was fitted with a new liner - new old Piston, the cylinder head had hardened valve seats etc. Was restored to a very high degree of reburb. The engine was rebuilt about 2 years ago and sat in my office while I rebuilt the rest of the bike, It was a total rebuild... this bike was a BSA shipped to Burma and used and abused until 1997... every part of this bike was worn out.

How would I know if the valves are not closing properly? I would welcome advice on this as I am not very familiar with how best to adjust them?

I will check my fuel tank cap to see if that could be the problem... I like simple reasons for the issue!!!

This is _so_ frustrating so really appreciate the advice!

Spoke with Kidderminster BSA who have set me on the right path. They suggested keeping it + despite the loom being set for - because there were issues with the - Control box/regulator they supply. Fine by me.

1. Setting polarisation of Dynamo - Set Dynamo to (+) flow by putting a wire from (-) terminal of 6V battery and swiping it against the Dynamo F terminal.
2.  Reverse the battery around so its + battery to - on the loom etc.
3. Reverse the Ammeter around.
4. Pop the new regulator in following their recommended diagram - to be sent to me.

I have to be honest that this is all new to me but I would like to thank you for all the help.

Hamish

Hi,

One question I do have is this wiring diagram for + or - earth... I am trying to workout if I have the right regulator fitted.

The loom is basically the same as the diagram attached. Its a standard Lucas magdyno as fitted to the BSA in 1955.

Any suggestions?

Hamish