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Messages - Barrieh

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Singles / Re: BSA m33 Brake Rod dimensions and kinks
« on: 22 March, 2022, 13:37:29 »

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.


Singles / Re: B31/B33 primary chain oil
« on: 21 March, 2022, 16:18:41 »
I found that putting too much oil impacted the clutch plates causing them to drag.

I would suggest a smallish amount in. It gets wiped around in there and so not a lot is needed.

Singles / Re: BSA Gearbox ratios - BSA M33/B33 etc
« on: 21 March, 2022, 16:14:04 »
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.


Singles / Re: BSA m33 Brake Rod dimensions and kinks
« on: 21 March, 2022, 16:08:16 »
That is amazing, thank you so much.

Via Tim Jeffrey I have managed to secure a new old stock 65-6279 rear brake arm for the hub. I will send it across to the SJ engineering company in Northern Ireland to see how we get some made up. The other options of twins 42-6075 and the 67-6053 have the wrong offsets and dont work well. There seems to be a shortage of the 65-6279 and given they do wear out and are somewhat consumable it would be good to get some made up.


Singles / BSA Gearbox ratios - BSA M33/B33 etc
« on: 18 March, 2022, 13:54:43 »

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?


Singles / BSA M33 rear brake arm 65-6279 Ö what others can I use?
« on: 18 February, 2022, 19:13:19 »

Need a replacement rear brake arm. Looking for 65-6279 but canít find any. Is there an alternative part that I can use? Has anyone got one they would be prepared to sell?


Singles / Re: BSA m33 Brake Rod dimensions and kinks
« on: 18 February, 2022, 11:59:17 »
Thatís 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.

Singles / BSA m33 Brake Rod dimensions and kinks
« on: 16 February, 2022, 14:54:31 »

Will Hogan at Stainless steel classics has kindly and beautiful supplies a new brake rod. Itís for an A7/10 so is too long but I will adapt for my 1955 BSA M33 Plunger. The old brake rod is pretty bad and while it works to a fashion is not good. Can anyone measure their plunger brake rod and tell me their kink angles and dimensions. A couple of photos to explain how it gets around the plunger units would be superb. I have said to Will I will send these onto him to aid his supply specifications.

Many thanks

Singles / Lucas E3LM - Advanced or retard question
« on: 19 October, 2021, 15:38:58 »

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?


Singles / Re: BSA M33 500 1955 Engine looses Power after 20 min
« on: 15 October, 2021, 17:12:27 »

Been busy at work hence no response... apologies.

It was the tappet, specifically the Inlet Tappet that was wrong. For some unknown reason the tappet lock nut had loosed off.

What is truly amazing is it was off by about 1/2 cm and yet still managed to run and function for the first 20 min consistently.


Singles / Re: BSA M33 500 1955 Engine looses Power after 20 min
« on: 17 September, 2021, 21:58:24 »

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!

Singles / BSA M33 500 1955 Engine looses Power after 20 min
« on: 17 September, 2021, 19:37:59 »

Bike has had a new engine rebuild, magneto rebuild, fitted with Amal concentric with 260 main jet (middle position needle) 19cc Idle jet 1 1/4 turned back. Oil getting to top of engine and back down on return pipe. Running Mineral SAE40 oil. Sits between advanced and retard even warm, doesnt like to advanced or too retarded. Carb has 10mm of heat protection with heat insulting plate... mildly warm to the touch after 20 min, not in any shape or form hot. Choke is fully open from the start and doesnt need any at all.

After 20 minutes of riding - getting up to 50mph, it slowly and surely starts to lose power to the point I have the throttle wide open it chugs along... sounds more throaty. Still idles well, but when hot gets slow, loss of power. When cooled it back to normal and will run quickly.

Any advice gratefully recieved.


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.


Thanks Derek. I am a little confused - my fault for not reading up enough on this subject.

I have a Lucas E3LM Dynamo fitted  60w - I am assuming for +,  so why have Lucas created wiring for negative earthed frame? Surely the wiring should be + earthed?

I am assuming you have the same setup. I have kept everything 6V but what regulator would I then need? I went down the solid state route but I suspect I have probably damaged this as it was a + 6 regulator.



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?


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