Hi,

I apologize for being so ignorant and asking a question as silly as this. .
I am very bad when it comes to British Motorcycles and worse when it comes to elctricals.
I have the following doubts.
1. what is the difference between the dynamos of a BSA M20 and the Matchless G3L?
2. Can they be interchanged?
3. Is the dynamo for the BSA M20 called a "Long Dynamo" and the G3L a "Short Dynamo"?

Regards

email (option): prabhin6386@gmail.com

The dynamos you speak of are different. I haven't got the spec or numbers in front of me right now. The M20 long dynamo you mentioned is probably the post war version which is 60 watts as opposed to the shorter wartime 45 watts. These are interchangeable and clamp on top of the magneto. The G3L dynamo is driven by a chain inside the clutch case, and will have a different body which is designed to fit through the engine plates.
The short answer is 'No they are not interchangeable' Ron

email (option): ronpier@talk21.com

Matchless Lucas E3AR, wiith tapered shaft for chainwheel.
BSA E3HM with parallel shaft and gearwheel

But for a layman they all look like a typical 3" diameter dynamo.

From L to R
E3AR
E3HM
E3HML

email (option): unpob@yahoo.com

Anything with a parallel shaft and the correct bearing end cap can be used.Can't be too fussy these days!