butterbean
Well-Known Member
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- Joined
- Jul 25, 2011
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98cc 4 stroke mini bike engine with agk jackshaft. Replace jackshaft output sprocket with belt pulley and install gebe sheave on rear wheel. Use existing chain tensioner (kit tensioner converted to spring-loaded) and attach some sort of pivot-arm such as a jockey shifter to increase/decrease tension on belt. That's my possible idea. Here are my questions: one, will it work the way I think it will (varying the tension on the secondary belt will change the speed/gear ratio even though the primary drive is still chain)? Two, what size pulley would I need for the jackshaft output in order to maintain current gear ratio (realizing I am attempting a multispeed bike so there won't be any fixed gear ratio until I control it with the shifter, but still wanting the pulleys to closely match current setup for a baseline ratio) (current ratio is 12.44:1, 11t at crank, 28t input, 9t output and 44t at rear wheel, the 44t at rear wheel will be replaced by a gebe sheave and I'm not sure how to calculate what size pulley to closely match current ratio). Thought about doing a shift kit, but I think a belt and a jockey shifter would be cheaper and simpler. Thoughts, opinions, and most importantly, ACCURATE info/advice?