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Goes flat at top speed...


Discussion at Motorized Bicycle Engine Kit Forum in the Motorized Bicycle General Discussion forum. I've seen this complaint many times here,and the other day I ran across an article on roller chain ...
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Old 11-27-2008, 08:52 AM
Walter F.'s Avatar
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Default Goes flat at top speed...

I've seen this complaint many times here,and the other day I ran across an article on roller chain drive designs. In it he says that any sprocket has a "top speed" and after that power falls off!! Maybe it's the sprocket not the engine?

Alright I don't know how to do a link but follow these steps

1 Google "Standard Roller Chain Drive Design"
2 First entry should be "Mechanical Design Handbook:Standard roller chain drive design
3 Click on here.
4 Read the article, but what I'm talking about is the paragraph above the drawing of Lubrication Methods

Let's see what you genius' think, if anyone wants to make an easier link feel free. Happy Thanksgiving Walter F.
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Old 11-27-2008, 11:34 AM
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Default Re: Goes flat at top speed...

Mechanical Design Handbook: Standard roller chain drive design
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Old 11-27-2008, 11:38 AM
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Default Re: Goes flat at top speed...

That's it, you all read it a see what you think---- Walter F.
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Old 11-27-2008, 05:41 PM
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Default Re: Goes flat at top speed...

I don't think he's talking about our applications....I don't think we coul;d ever turn one fast enough to get to the place he's imagining.

Usually our bikes "fall flat" due to fuel foaming, (vibration) or just plain running out of power. (two horsepower can only do so much)
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Old 11-27-2008, 06:22 PM
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Default Re: Goes flat at top speed...

With a 14mm carb you can only flow so much air, so you cant get enough fuel to the engine because of the lack of air at WOT, the engine just runs til it wont flow anymore. I have a 18mm Mikuni and it doesnt "fall flat" like the stock carb...
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Old 11-28-2008, 07:38 AM
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Default Re: Goes flat at top speed...

Quote:
Originally Posted by Bikeguy Joe View Post
I don't think he's talking about our applications....I don't think we coul;d ever turn one fast enough to get to the place he's imagining.

Usually our bikes "fall flat" due to fuel foaming, (vibration) or just plain running out of power. (two horsepower can only do so much)
Joe let's think outside the box for a minute, first have you ever seen this fuel foaming phenomenon happen?

If at wide open throttle your turning 6,000 RPM, the little drive sprocket is turning at 1590+RPM OR 26.5 Revolutions Per SECOND. I think this is probably fast enough for a few laws of physics to apply, and I wouldn't call it an imaginary place.

Joe, I'm not saying this is the answer but I'm thinking it might be part of the answer. I just threw it out there for you guys to chew on. Happy Hills & Trails Walter F.
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Old 11-28-2008, 08:00 AM
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Default Re: Goes flat at top speed...

Walter- I have seen it happen, and not just on our type of engines.

Our chains/sprockets would be subject to the forces of physics, just not enough to slow the bikes down a perceptable amount.
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