top speed 20 mph

i just put a new imitation bing carb, with a #68 main jet (, on my 78 puch maxi. To my dismay, it tops out at about fifteen to seventeen mph. When I take the airbox out, i can reach a little over 20 mph, but the acceleration is significantly reduced. The exhaust is stock. any suggestions on how to increase the speed?

Re: top speed 20 mph

That jet might be a little big for an all-stock moped. What size is the carb (and intake)? Have you checked for air leaks? Or run a plug chop? What's your gearing? Do you have the 1hp model?

Re: top speed 20 mph

It's a one 1hp model. I have not run a plug chop yet - waiting until i can go somewhere with enough space. also, not sure about my gearing (actually, i'm not even sure what that means). i guess the carb is a 12 mm or 14 mm.

Re: top speed 20 mph

one hp models are restricted by either the cylinder or a plastic piece in the intake, and the exhaust. the plastic piece can be removed.

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