Puddle Jumper's belt drive


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Since as a non-member I can't reply in the Help needed thread, I'll start a new one.

Is the 3" belt drive dictated by the clutch, because if not that's real overkill? On the racer we were using (if I remember correctly) a 2" belt drive with a Norton clutch, might even have been a bit narrower. At the end the racer was putting out over 100 bhp at the rear wheel (in it's 1200 cc guise) and we never had any problems.



Tom Gaynor

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Belt drives

Standard classic racing drive belt is 1", used on everything from 350 Nortons up to Weslake mega-twins. I've broken one belt in 15 seasons. A stone got in, frayed the (probably 5 year old) belt, I failed to notice, and it let go. I guess I've replaced the belt on a ~50 bhp 500 Manx three times in fifteen years, and the crankshaft pulley (it's ally on a steel splined mainshaft) once.
(The answer isn't to enclose the belt, because then if a stone does get in, it can't get out, and it wrecks the belt even faster. I know someone who found this out for himself...)


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Then we were probably also using the 1" belt, since we were also using the Newby clutch. It's about 13 or 14 years since I sold the beast, so my memory's fading a bit!
Whatever, I don't remember ever having any problems with the belt drive, unless Ian neglected to tell me about it! :)
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