BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: Group Leader on 17 November, 2021, 20:07:36

Title: BSA Part Numbering
Post by: Group Leader on 17 November, 2021, 20:07:36
I've recently had the need to remove the cams from my B21 single which should both be the same part number.

What I've found is that the inlet cam is numbered "65-2438"  and the exhaust cam number is of a very different form, specifically "A2-1".

The inlet cam is definitely the wrong part number for the bike (from a Gold Star I believe) but my question is is the "A2-1" number a later BSA equivalent number or is it an aftermarket part number?     Is there a conversion chart / table that shows the equivalents?

Any advice gratefully received!

A rather confused Alan
Title: Re: BSA Part Numbering
Post by: idie on 17 November, 2021, 20:49:03
 The cam 65-2438 is a early 500 goldstar cam and I think you will find that the A2-1 is a cam for a B31 or B33 used both for inlet and exhaust.
Title: Re: BSA Part Numbering
Post by: chaz on 18 November, 2021, 09:46:13
I suspect, it was , "what was available" , when someone rebuilt it previously, or even a tuning tweak.
Title: Re: BSA Part Numbering
Post by: Group Leader on 18 November, 2021, 16:29:12
You may very well be correct! 

Unfortunately what was to hand didn't seem to be in very good condition as it looks like lobe on the inlet has been "restored" (I use the term very loosely you understand!) by welding and grinding.   Well, nice try but no Cigar ....

My question is aimed at understanding  the differences/similarities in the part numbers so when I plump for replacements from a well known internet auction site it can be done with a modicum of knowledge of what is sensible and/or viable.   I certainly don't need or want "hot cams" for the ultimate in performance, I just want it to run well and run reliably (something hitherto sadly lacking)

Alan
Title: Re: BSA Part Numbering
Post by: idie on 18 November, 2021, 18:02:19
I would try a pair of B31/33 cams as a starting point. You have one already.
Title: Re: BSA Part Numbering
Post by: Group Leader on 18 November, 2021, 19:47:26
I would try a pair of B31/33 cams as a starting point. You have one already.

Thanks, sounds like a plan  :)