Absolute Fastest Motorized Bicycle YD100 Engine On Planet Earth! Nuked On C85 (50/50 Nitromethane)

curtisfox

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Dec 29, 2008
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minesota
Hey will y'all believe my bike goes 32 mph?
I believe, my old Marnark twin did about 35. as well as my old 1 1/2 hp Brigs home built, about 30. I built it it went about 25 then I ported the intake and exhaust, jumped the speed up. It takes a lot of hp to get the speed up much more then that...........Curt
 
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Sidewinder Jerry

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Dec 19, 2011
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Not me, the guys that have been here a while understand when someone new is trying to impress them with what they have done. I’m at the other end of that spectrum, I think it’s kinda impressive that two of my three bike engines are over 10 years old with one with a top end that is all original except the head.
My Robin Subaru 35 is 12 years old so is my triple chainring shift kit. The reduction range is 66.79:1 to 16.25:1. All I've ever replaced is the spark plug and the old non adjustable Walbro carburetor. I now carry a spare adjusted carburetor with me. I can do around 28 mph on level ground and around 8 mph up 30% grade hills. My weight combined with the bike is a total weight of 350 lbs.
 
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Greg58

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May 1, 2011
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32 is fast for a 48cc, neither would go over 26-27 before I started tuning. The fastest one I've ramped the piston to improve port timing, both needed the intake side of the piston trimmed to clear the intake port. The right pipe makes a difference too, I've tried several till I found what works best for me.
 
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Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
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Not me, the guys that have been here a while understand when someone new is trying to impress them with what they have done. I’m at the other end of that spectrum, I think it’s kinda impressive that two of my three bike engines are over 10 years old with one with a top end that is all original except the head.
I'm actually impressed that you have enough self control to only have three bikes! laff

I totally agree with you... I'm not impressed with claims of top speed, or when someone bolts on every billet part he can possible find... I'm impressed when things are clean, simple & reliable.
Even when you look at some of the fanciest bikes that I've ever built; they're still very basic in their mechanical design.
 
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Greg58

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May 1, 2011
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Norm I’ve got a couple of frames, I’m thinking about doing one with a 66cc converting it to a steel sleeve 49mm bore, I’m just thinking right now but who knows.