Early B33 (1947)

[MGI]

I am trying to locate BSA part no 65 2539, which is a sleeve with internal & external broaching which fits on the primary chain side of the engine crank and allows the installation of a 2 lobe cush drive unit as opposed to the original 4 lobe unit. Any help would be appreciated.

[idie]

Are you sure the sleeve is different. I don't remember changing it when I changed the sprocket on my M33 from 4 to 2 lobe. I will have to go to the garage and check.

[MGI]

Phil Pearson junior informs me thus!

[idie]

I have just checked, you are right the four lobe sleeve has its grooves closer together. Make sure that the sleeve is for the singles. I think the ones for the A  type engines have a slightly larger hole.

[MGI]

Well, I suppose you would expect Phil Pearson to be clued up on the subject, I am another matter. Anyway, Edie, thank you for checking it out. Incidentally, you are spot on with your warning... the early A series are different and they can be identified by a slight groove running around one end of the sleeve! I have finally sourced one from George Prew, just hope it is the correct one - it was hellish expensive!

[idie]

Wll the price is no surprise. At least you are moving forward.

[morven21]

Yes, price of stuff these days!  I remember, just, when Pride an Clarke were selling new M21 engines for £25. . .

[idie]

I loved browsing in Pride and Clarks, not far from where I lived at the time.

[MGI]

The sleeve has arrived and... it has a slight groove running around the outside of the shoulder at one end! I don't believe it! I am concerned that it is the wrong one!

[idie]

Try it first before condemning it. Sometime you need to leave out the spacer that that sits against the bearing. I have noticed that there is many variations on the sleeve.

[MGI]

Could anyone tell me if the cush drive assemblies on the swinging arm B31/33 models are the same as the A7/10 models other than the amount of teeth on the primary sprocket?

[JulianS]

No not the same, cush bearing to crankshaft spline is different and there are several different but similar versions of the cush bearings.

[MGI]

Thank you Julian..(and Idie)

[MGI]

Panic over, I thought the sleeves with the faint groove around one end was for the A series wherein it is actually the reverse. I now have a two cam cush drive on my bike (Not to mention an electric start kit) and everything is good. Incidentally, the engine sprocket was discovered to have 22 teeth (I thought 1st gear was a bit high) and it now has 21 teeth which makes it much easier to get going. I have now learned that my machine has Gold Star forks & 8" front brake, an A series rear sprocket and a non BSA clutch - it really is a bitsa!

[idie]

You have an electric start kit for a B33 with a steel primary chain case? Who made it?