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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.


Throttle/Acceleration Problems

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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  #1  
Old 12-17-2013, 05:08 PM
JoshuaYoung JoshuaYoung is offline
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Default Throttle/Acceleration Problems

Hello, I've has my bike for about a month now! I was noticing that when I'm riding it and go full throttle, the bike slows down like it wants to shut off after about 4 seconds! I don't know what can be the problem!! Anyone have any tips?
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Old 12-17-2013, 06:47 PM
crassius crassius is offline
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Default Re: Throttle/Acceleration Problems

bad vent hole in the gas cap comes to mind - loosen the cap & see if the problem goes away
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Old 12-17-2013, 07:33 PM
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Default Re: Throttle/Acceleration Problems

It would help if we knew what engine and carburetor you have.
It's hard to make suggestions if we don't have some basic information.

Tom
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Old 12-17-2013, 08:10 PM
JoshuaYoung JoshuaYoung is offline
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Default Re: Throttle/Acceleration Problems

I will try the gas cap tomorrow! And I have the regular 80cc engine ! Nothing fancy! And I have the stock carburetor !
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Old 12-17-2013, 08:34 PM
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Default Re: Throttle/Acceleration Problems

There are no 80cc engines, only bad marketing and lying that they are actually 80cc.
You most likely have a 66cc engine.
There are 5 kinds of "stock" carburetor.
NT, NT Speed, CNS V1, CNS V2 and CNS V3.

Where did you buy it from?
Can you share a link or perhaps a photo? Some way we can get a better idea of the engine in question and what you have on it?

My blind guess is either the aforementioned gas cap problem or the carburetor's float height is set too low. It could be a poorly flowing petcock too.
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Last edited by GearNut; 12-17-2013 at 08:36 PM.
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Old 12-17-2013, 08:55 PM
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Default Re: Throttle/Acceleration Problems

Has this problem been there from the first or something that has recently become a issue?
I concur that a restricted fuel system might be the problem. Are you using an in-line fuel filter? Did you clean and flush the fuel tank before installing it? Have you disconnected the fuel line from the carburetor and checked for a constant flow of fuel from the tank?

How does it idle?
What is the spark plug gap? What fuel to oil ratio are you using?
All of these can have an effect on how the engine performs and cause the symptoms you describe if not correct.

Tom
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Old 12-17-2013, 09:41 PM
JoshuaYoung JoshuaYoung is offline
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Default Re: Throttle/Acceleration Problems

Yes this has been a problem before but never to the point where the engine slows down this sudden ... The problems I've had

1. I've replaced 2 clogged fuel filters
2. Replaced a petcock last month with one that still flowed but not as strong because it had paint chips
3. The carberutor tends to leak and fill with gas through the air filter
4. The fuel ratio I use is 4 ounces of oil to 1 gallon! I'm supposed to be using 2 ounces!

So based off of all these problems , can you guys give me a list of things to do in order to troubleshoot my problem
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Old 12-18-2013, 10:05 AM
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Default Re: Throttle/Acceleration Problems

1. Clean out the fuel tank thoroughly. As they come from the factory they are known for having rust and junk inside them.
2. Clean out the petcock.
3. Fuel leaking out of a carb is a sign that there is debris stuck in the float needle valve, the float height needs adjustment or the float has a pinhole and has taken on fuel.
This is assuming that the carb is sitting flat and level or pretty close to it, depending on how the engine has been mounted.
4. If you are using dino oil then a 24:1 ratio is good for break in. 32:1 is good after that for the rest of the engine's life.
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Last edited by GearNut; 12-18-2013 at 10:23 AM.
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Old 12-18-2013, 07:19 PM
JoshuaYoung JoshuaYoung is offline
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Default Re: Throttle/Acceleration Problems

I tried to ride it with the gas cap loose! Still no luck ! I took off the air filter and it was soaked in gas! Do you think the carbeurtor was the problem? If so I might just buy a new one !
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Old 12-18-2013, 09:43 PM
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Default Re: Throttle/Acceleration Problems

Quote:
Originally Posted by GearNut View Post
1. Clean out the fuel tank thoroughly. As they come from the factory they are known for having rust and junk inside them.
2. Clean out the petcock.
3. Fuel leaking out of a carb is a sign that there is debris stuck in the float needle valve, the float height needs adjustment or the float has a pinhole and has taken on fuel.
This is assuming that the carb is sitting flat and level or pretty close to it, depending on how the engine has been mounted.
4. If you are using dino oil then a 24:1 ratio is good for break in. 32:1 is good after that for the rest of the engine's life.
Before you invest in a new carb try the suggestions Gearnut offered. You might save yourself a few bucks. Typically there is little that can go wrong with the carburetor. The biggest problem is usually a clogged needle valve or a cracked float that has sunk.
Check those things before spending your dollars.

Tom
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