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Discussion Starter #1
This isn't a twin question but anyway....

I eventually intend to build a Cub Trail type bike and continue to use the nacelle speedo. It'll have a period look.

I'll have bigger wheels and tyres than the standard so will need to use a non standard speedo drive. (i don't have one with the pile of parts that will make the bike anyway)

So have does one figure out the ratio? I guess that the speedo has one and That I ned to know the circumference of the fitted tyre.

I know that I can fit an electronic cycle type but want the "real deal"
 

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1) I believe a Cub old enough to have a nacelle drove the speedo off the gearbox.
2) The only rear wheel speedo drive ratio commonly available is for the big twins with 4.00-18 K70 tires.

You can't get optional internal ratios for the Cub engine, and the rear wheel ratio simply ain't going do anything buy lie to you. So why bother worrying about this?

You got much bigger problems, like how to keep a plain bearing Cub engine together. :D
 

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Discussion Starter #3
yeah, fragile little buggers, cubs.
or maybe just thrashed more than Turner planned. Sadly, the later bikes were nearly sorted out and then they dumped the model.

The era of cub (1960) that I have used a rear wheel drive that wasn't supplied with the bike. I've found an article on line from the AJS owners MCC that gives the maths but need to look at the speedo and see what ratio that is.

If I come up with a solution, I'll post back as someone might find it useful.

I'd guess that I'll have trouble keeping up with traffic on less urban roads but we have a lot of cameras here and it's easy to be a bit over and get a ticket. Dunno how it works in the states but too many points and you get a ban.
I have points
 
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