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Old 06-04-09, 12:45 AM
  #11  
Flash_BeeZy
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Join Date: Jun 2009
Location: San Jose. Ca
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Bikes: surly Steamroller, Mercier Kilo TT pro

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Originally Posted by Spasticteapot
I call BS.

I have never seen a 50cc engine produce 15HP. Ever. Show me a dyno test, and I'll believe you. Top-spec 125cc kart engines can produce 30HP on a good day, and those cost a small fortune.

Even in the case that you are producing such an enormoujs quantity of power, there's the stress on the internal components to be considered - you're placing a huge load on all the moving parts in the engine. Aforementioned kart engines are extremely unreliable for this reason, and require regular overhauls.

Secondly, 2-stroke tuned pipe motors have an extremely limited torque band - it's the nature of a tuned pipe. Unless you're at or close to the resonant frequency of the pipe, there's no power boost. Go talk to a moped mechanic if you don't believe me. (If it's not a 2-stroke - which is pretty unusual for a 50cc dirtbike engine - then there's simply no way you're getting 15HP, period.)

Finally, you're looking at ancient E-bike technology. 15 pounds of LiFePO4 batteries would give you a 60+ mile range, and a 20+ horsepower 3-phase brushless motor weighs a lot less than your 2-stroke - net weight compared to a petrol engine with full tank is about the same. An electric system requires nearly zero maintenance, has effectively only one moving part, and unlike a carburetor won't regularly require adjustment.

Leave carbon footprint out of the picture - as you said, it's a moot point either way (though I should mention that 2-stroke motors are major smog producers - you're probably in the same league as a hummer.) While they do require a bit more money and a high school physics education, they offer tremendous performance.
Call bs all you want my polini/bizeta 50cc 5 port factory reeded,ported pocketbike motor makes 15hp its a $1200 motor and yes i pay good money for these components .geared for a pocketbike its known to hit 70+ not saying i have but attend races and actually see it. As for mopeds i know of a similar machine being polini powered and having only 50cc hitting 70-80. Also sure 125cc karts have 30hp i believe it gotta account its a 4 stroke,has at least a 6 speed gear box and lord knows what else...120+ top speed? I can only dream...

I pay top doller the motor on the bike isnt cheap nor of china quality

Flame on...
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