bike has good low in power no top end

[toolow]

i cant get this thing to run it has lots of power on take off and mid range but has no top end what should i do i have 80cc matched intake and exhaust ported them to and i have an expansion chamber anther thing is it doesnt run very good with air box on it

 

[retromike3]

something to think about

I also had a problem with low power in the higher RPM after I added the sick bike parts pipe. All I had to do was cut about a quarter of a inch out of the pipe going from the manifold to the chamber. My low end was still OK but my high end improved quite a bit.

On your pipe it might not be an option.

P.S. When I try to upgrade my engine I just do one thing at a time because that way its easier to tell what is really working.

Mike Frye A.K.A. Frye Bikes

 

[toolow]

Thanks I will try that

 

[GearNut]

Just an off chance, too rich of a fuel setting near WOT can make an engine "blubber" at higher speeds and severely hurt power output.

 

[toolow]

so do i need to move needle clip up or down

 

[GearNut]

Move the needle clip up, away fron the pointy end, one groove.
Be carefull! You do not want to have the mixture running to lean.
Remove your sparkplug and check the color of the inner porcelain frequently after making this kind of adjustment. You want it to be a chocolate brown color. Light tan or white is too lean and will cause damage. If this does not help, you may need to go to the next size smaller fuel jet. I do not suspect this though, as the jet only affects WOT fuel delivery. The needle affects midrange and near WOT.

 

[Fabian]

Be thankful your bike has lots of low and midrange power (the standard exhaust pipe is great for that) - use it to good effect and you won't blow your bottom end conrod bearing.

Fabian