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Old 03-06-2015, 10:30 PM
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Davezilla Davezilla is offline
Motorized Bicycle Elite Member
Join Date: Mar 2014
Location: San Antonio Texas
Posts: 2,710
Default Re: Good, two stroke motor kit.

Been thinking on the same lines since those trials bikes have so much bottom end torque... not a whole lot of top speed, but no need to go above 25 mph on those to have a lot of fun.
My thoughts on the engine are nice wide ports with a low ceiling on the exhaust and a high floor on the intake side or maybe a reed valve setup on the intake, as much compression as I can run on pump gas, a good dirtbike pipe with some extra header length added, and modify the mag coil mount to make the ignition timing adjustable and the engine should pull hard below 5000 rpm.
rear sprocket size could be 48 to 56 teeth on a 24" wheel with some fat agressive knobby tires and a 26" front, it would look sick and pull like a freight train if the engine is tuned to perform best at 5k rpm and below... I got a few ideas how to set up an engine like this but I'd still like to see some port maps for trials engines to get a general idea how they map them out for lots of bottom end torque for those quick bursts of power.
A smaller carb would also help since they tend to be more responsive and there's no real need to rev the engine sky high.
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