Goes flat at top speed...

Walter F.

New Member
Jun 4, 2008
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Connecticut
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.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
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)
 

misteright1_99

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Mar 21, 2008
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Treasure Coast, Florida
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...
 

Walter F.

New Member
Jun 4, 2008
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Connecticut
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.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
237
63
up north now
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.