Magneto drive for dominator

I want to fit a magneto to my 850 Commando motor and am looking for the idler gear with the sprocket to drive it. Is it the same as the one used on Commandos to drive the points and the cam ? Or does it have two chain sprockets ? Where would be the best place to start looking for it ?

acotrel said:

…Or does it have two chain sprockets ? Where would be the best place to start looking for it ?

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It has two chain sprockets. Parto-NO: 50008. Norvil has it: http://www.norvilmotorcycle.co.uk/timing.htm. NOC has some (with pictures). They state «for dynamo models» I'm not sure if there is a difference.

Fritz

Al, check this Ebay item No. 381824785497

and the magneto sprocket Ebay item No. 391603578895

acotrel said:

I want to fit a magneto to my 850 Commando motor and am looking for the idler gear with the sprocket to drive it. Is it the same as the one used on Commandos to drive the points and the cam ? Or does it have two chain sprockets ? Where would be the best place to start looking for it ?

Click to expand...

The 20M3 twin chain motors are hugely different in all aspects of spacing. The 20M3 timing cover won't easily work on a 20M3S+(850) commando motor though the 2 dowel pins, screws, idler shaft line up...different oil relief, You will have to change to an early cam and cam drive sprocket, plug the tach outlet.,
The list of mods required will be long as your arm.

Yes almost anything CAN be done with enough work but It would probably be far easier to fit 850 barrels on a 20M3 early commando than what you propose to do.
Easy to figure out with the items to play with in my machine shop or in the office window:
1950-1961 500-600-650

1963-1975 20m-20M3-20M3S-2xxxxx-3xxxxx-325xxx

Thanks, fellas. Well that sounds like the end of that good idea. So I'm back to looking for a small lithium ion battery. In any case, I probably would have ended up trying to find another Lucas SR2 magneto and these days I don't think I'd find a new one.