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Old 08-30-2011, 03:54 PM   #24 (permalink)
Stick your neck out...
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Join Date: Jun 2011
Location: Essex UK
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Quasimoto – to be honest, until you mentioned it, I hadn’t put much thought into “unsprung weight”, although it’s a subject I’m very familiar with. My best guess is that of the 45kg increase only 10kg will be unsprung. The bigger (heavier) tyres and brakes are only about 5kg per end, and it’s a necessary evil as I must improve the spec to make it suitable to use at the higher speeds. But think of this – why will this significantly impair my ability to reach the 100mph target? Unsprung weight will play no part in straightline performance, its major effects will be shown on “ride and handling” and even then the better tyres brakes and dampers should outperform the stock C90 kit.
Patrick – yeah, the “jackshaft” was an unintended consequence, and I acknowledge that it will reduce my driveline efficiency, but its there now and fabrication has finished with reasonable solution, so I’ll stick with it! But if I posted images and weights, I would be interested in how big you think the losses will be. My stock motor gives (supposedly) 7.5hp, and I’m aiming to up this to 10hp to reach the 100mph target – would another 0.5hp cover the losses?
On the starter thing – I bought the “electric start” version of the C90 already, and I plan to keep the original charging system and battery on the revamped vehicle.

Thanks to both of you for your input! Let me have more, particularly on the aero and body design side. This project is all about how you can take a low power vehicle with a modest top speed and make a “fast & frugal” motorcycle – and aero is the key!
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