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Old 01-20-2015, 02:23 AM
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bairdco bairdco is offline
a guy who makes cool bikes
Join Date: Aug 2009
Location: living the dream in southern california
Posts: 6,260
Default Re: Top Speed, 80cc Chinese motor? what is the record?

my race bike now has a modified ktm expansion chamber, mm ashtray head, 22mm mikuni and "backwards" engine (carb's in the front, exhaust out back.)

24" wheels and a 37t sprocket. and it weighs 53lbs.

i gps'd it at 46mph. it still revs out with that sprocket. i could easily pull a 28t and hit 50+, but it's geared for the relatively short straights at the gokart track and needs to be quick out of the turns. this season i'm gonna try out a 40t. sacrifice some top end to gain more torque outta the twists.

the key to top speeds is gearing. if you're designing a bike to do nothing but go ast fast as possible, you'll need to sacrifice low speed quickness. a low gear, a looong straightawsy, and just let it freight train along until you get there.

the trick is building a motor that won't run out of torque to pull such a low gear. putting a 30t on a stock china and you'll go nowhere, slowly.

i call bs on speeds over 40 with an untouched stock
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