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Re: How many teeth on sprocket for BSA M21?
Re: How many teeth on sprocket for BSA M21?

This item is out of stock. ☹️ Try BSA de Groot. 👍😅

email (option): John.kater@chello.nl

Re: How many teeth on sprocket for BSA M21?

Your final selection will also depend on whether you have an 18T or 19T gearbox sprocket fitted...I think most of the comments so far relate to British WD machines which were fitted with an 18T gearbox sprocket.....Ian

email (option): ian@wright52.plus.com

Re: How many teeth on sprocket for BSA M21?

Hi Ian,

Thank you for the reply.

I have got a 19 teeth sprocket on my gearbox. What would you recommend?

Regards,
Bastiaan

email (option): recce_van_niel@hotmail.com

Re: How many teeth on sprocket for BSA M21?

It rather depends on what you use the bike for most of the time...
If your ride a lot in traffic, in town, or live in a hilly area 19T...If you live in a less hilly area and do more main road riding in more open country I'd go for the taller gearing of 20T...Ian

email (option): ian@wright52.plus.com

Re: How many teeth on sprocket for BSA M21?

Also depends on how fat you are. I'm about 12st all up with clothing. 20 teeth for me in the hilly Welsh Marches. I've tried both.

email (option): jeremy@clogmaker.co.uk

Re: How many teeth on sprocket for BSA M21?

Hi bastiaan

I run my relatively low compression m20 on a 20tooth

It accelerates even slower than before but delivers in my opinion a cruising speed with less buzzing from the motor & vibes

It does however feel it on hills - not so much a problem where you live

The m21 motor I have in mind for my 1940 bike I will start with a 21 tooth - i think it will take it

Standard gearbox gearing retained

Br

Jo’b

email (option): jonnyob1@googlemail.com

Re: How many teeth on sprocket for BSA M21?

Hi Jo'b (and others),

Thanx again for the advice.

I have found out that it was very specifically mentioned in the contract for the Dutch Army WM21's which sprockets should be fitted to the engine and gearbox (both 21 teeth). I will add a photo I have made from that contract and from the BSA partslist for comparison. The contract is in Dutch, but the gearbox ratio's are easily compared with the 1940 partslist.

Regards,
Bastiaan

https://imgbbb.com/image/p9KsJ


https://imgbbb.com/image/p9wwU

email (option): wdmotorcycles@gmail.com

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