kh dynamo

[robin rose]

I have two drive gears for the Lucas E3L dynamo that is to go in to my 52 KH. One 22 teeth and one 24.
Which one is applicabe to the KH anybody please. Drags part list is unspecific for the KH.
thanks.

Rob.

[jj.palmer]

Robin, the centre distance between the driving gear mounted on the exhaust cam and the gear mounted on the dynamo is fixed ie. not variable, therefore it will be obvious which gear is the correct one to fit in order to achieve the correct gear meshing.
If you are still unsure I will happily slide the dynamo out of my KH and count the number of teeth.

Regards,
John P.

[pete.collings]

It should be the 24 tooth gear for a KH, I recently fitted one for a friend who had a 23 tooth gear on his 1957 KH dynamo, which showed an uneven wear pattern. The correct gear has a step at the back to align the gear with the driving pinion (much the same as a Triumph dynamo gear, although this has 25 teeth), although when fitting the dynamo you need to have the correct thickness of cork washer to ensure the gear doesn't make contact with the timing chain.
The dynamo for the singles has the 22 tooth gear with a flat back face, which was increased in length to suit the 60 watt dynamo.
I don't know if the earliest KH had a smaller dynamo gear, perhaps someone with such a bike could advise.