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Motorized Bicycle Trouble Shooting Use this area to post problems that may arise, if you could use some help in figuring out what is wrong with your engine and what needs to be done to achieve top performance.

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Old 01-26-2013, 10:05 AM
moonerdizzle's Avatar
moonerdizzle moonerdizzle is offline
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Location: Cheese head capitol
Posts: 874
Default Re: No power gain after installing header and bigger camshaft in HS

want a bigger carb? make a manifold and slap on a CNS like i did, but like stated before, a cam is useless with out a better carb and exhaust.
that effin moon kid

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Old 01-27-2013, 04:12 PM
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socialdistortionkid socialdistortionkid is offline
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Join Date: May 2011
Location: Orange County, CA
Posts: 187
Default Re: No power gain after installing header and bigger camshaft in HS

Originally Posted by GearNut View Post
You need a bigger carburetor to allow more air into the engine.

A bigger hole in the fuel jet will not allow more air into the engine, only more gasoline which will upset the state of tune of the carburetor.
Mess with the fuel jet more and you will have one heck of a krappy tuned carburetor.

Your problem is not in the fuel delivery.
You can drill away at the main jet until the cows come home and there is no main jet left to drill and you will still have the problem.

Your problem is in the volume of air flow that can pass through the small throat of the stock carburetor.

Get a carburetor with a slightly bigger throat.
Tune the carburetor to deliver the proper fuel needs of your engine.

Enjoy the new found power.

Remember, a 4 stroke engine is just an air pump.
1. Suck the air and gas in. (intake stroke).
2. Squeeze the air and gas tightly (compression stroke).
3. Ignite the gas and air (power stroke).
4. Blow the spent charge out (exhaust stroke).

What you have done is to almost allow more air into the engine which will increase the power output.
You have a better exhaust = more exhaust out.
You have a racing cam = higher percentage of cylinder fill potential at high RPM's.
You will never see that potential if you have a dinky carburetor starving off the air that could be filling the cylinder.

The carburetor just needs to be a little bit bigger.

You may need a custom made intake manifold, or ask AGK or similar high performance motorized bicycle stores about it. They may offer something that is not posted in their web store, or know of one that will suit your needs.

I completely understand now. Thanks for the detailed explanation. I appreciate it.
I would rather live a short life filled with fun than a long life filled with boredom
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