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Old 09-28-2014, 09:47 PM
Slogger Slogger is offline
Motorized Bicycle Elite Member
Join Date: Sep 2014
Location: nohio
Posts: 499
Default Re: Herky jerky slow speed cruising?

Like you I want to go slow and smooth but I'm stuck with a 40 tooth, for now. I am putting on a longer intake manifold to smooth out the lower rpm ranges, although it will cost some top end revs. One dude extended his to about 7 1/2" and liked the results, but his motor had other mods.
The test data he based it on was the results of long manifolds on a 149cc engine. It's intake manifold was also about 1.2" dia and worked great from 6.3 to 10" long, the longest worked best below 3500 rpm, but going limp at about 5000. This data was from a 149cc piston ported 2 stroke. (similar to the china girl)

Scaling it down, I'm just going with the length of an offset manifold, about 4" for starters. Anyway, I think a longer intake manifold might help your engine run steadier and stronger at slow speeds.
Good luck with it!
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