Dynamo chain

[Superflash]

So....went to put the dynamo chain on and it looks to be an inch or 2 too short. Question is.. are there different chain lengths or have I missed a trick somewhere? Cheers

[Slymo]

Looks like a big sprocket on the generator side maybe?

[RichardL]

Appently, you have the chain for the 11 tooth dynamo sproket , while yours is 13.

Richard L.

[Superflash]

Thanks for the info. I see Mike's classics has a 52 link chain. Mine is 48 and with the 13 tooth dyno sprocket me thinks that be the problem.  Is there any reason why I can't use the 13 tooth sprocket? Cheers

[RoyC]

  Is there any reason why I can't use the 13 tooth sprocket? Cheers

Just means that your dynamo will run a little slower.

[Swarfcut]

 Other possible is that the chain is the shorter A7 Longstroke type, in combination with the wrong dynamo sprocket.

 Swarfy.

[Rookie_V#60]

  Is there any reason why I can't use the 13 tooth sprocket? Cheers

Just means that your dynamo will run a little slower.

Ok will be 18 % slower, I don't think you can neglect that.

[Superflash]

Thanks guys. Pretty much just as I thought. So have tracked down an 11 tooth sprocket and a 52 link chain. Hey I see Mike from Mike's classics has got the business up for sale..... 

[trevinoz]

Have you got a long generator or a short?

[Superflash]

It's 190mm. Imagine my surprise to find out there are long ones and short ones.  Then again why not..... nothing else is standard or simple with these bloody things.

[trevinoz]

Different type for different years.
The short 45W generator was used until 1948 or 49 and superseded by the long 60W generator.
Short has one pole screw and long two.
Short uses 13 tooth sprocket and long uses 11 with obviously different chains.

[tore]

Information about type of BSA A7 dynamo chain:

You can find it with Renold number 110500 or ISO number 05B-1 (Pitch 8mm,  Inside Width 3mm).

There is also spring link (26) available for the chain. I have obtained spring link (110500/26 or 05B-1/26) and used it when installing the dynamo chain. It make dynamo installation much easier.

It also make possible to obtain 52 link dynamo chain and shorten it to long stroke (48 link) use.