Quote:
Originally Posted by sendler
I asked this a while back but didn't get any answer. In choosing a donor bike for a full streamliner conversion, what is the overall efficiency of a V-Matic scooter transmission versus gears. How long do the belts and drives last? I have read on the scooter forums that these CVT transmissions can wear out the belt and groove/ put sticky spots in both pulley assemblies every 5,000 miles. .
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These vbelt cvt's (the v-belt stage) can be 96% efficient, with some manufacturers claiming even a little higher. The same is true of any v-belt drive, if properly tensioned. (Gates, I think uses 97%, maybe.) The CVTs are self-tensioning, so the effective ratio changes (minutely) with a stretched belt, but the tension does not. Different systems have different numbers of gear meshes before and/or after the CVT. 98% for each mesh is a reasonable estimate.
At very low speeds, when the drive is not fully engaged (which happens in different ways with different scooters (some have independent centrifugal clutches, some use the v-belt drive unit) efficiency is awful.
If your streamliner is for you own use, and not for a competition, then the packaging ease and compactness of the scooter motor transmission unit is appealing, and may outweigh efficiency concerns . If you want, you can be seated over the front of the motor, while still having a low seat height.
Disadvantages include the difficulty in changing final drive ratios, and maybe 5% overall lower efficiency -- but that's assuming identical engine efficiency: the 150 is apt to be more efficient at 10 hp than a 250 cc bike at 10 hp. Honda has been publishing fuel economy numbers, which I think are reliable for comparing Honda models against one another. The 91 mpg quoted is pretty impressive as compared to the CBR 250's 77 -- which is a very efficient 250.
Some of the larger scooters have very high priced belts in the name of efficiency (they bend more like a chain). One I checked was about $250 or so.. or maybe $350... a lot in any case.