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CRF / XR70 CLUTCH Question

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I see some of you guys talking about the primary gear on these little engines.

I think I saw where some of you were putting 50cc clutches in the 70cc engines ??? What does this do if you do that...

When you order these aftermarket auto clutches what all comes with them (such as TB's HD clutch).

I saw where the TB Heavy Duty 50cc and 70cc clutches have different part numbers... clue me in.

Mike

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different sizes, the 50 is geared lower intenally more than the 70.

something close to a one tooth on c/s is the differemce in feel.

go with the 70.

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The 70's primary gearing (3.722) is much taller than the 50's (4.058). This, along with the 70's taller final drive (15/36 vs. 14/37) and it's larger wheels make it a total slug on acceleration. Unless you ride on big-bike tracks or are just going for top speed you'll find the 50's primary gearing makes it much more fun to ride, if done with a final drive change as well. Stock, the 70 is so overgeared that it will hardly pull it's own weight!!

You'll need the 50's two primary gears as well as the gear in the clutch that mates to the front (small) primary gear. Some of the older 70's have this ratio and a lot of primary gear sets and stock 50 clutches are available on eBay from people who've put the manual clutch kits on their fiddies.

All the manual clutch kits I've seen have the 70's primary ratio. Anyone know of one that doesn't?

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