Throttle/Acceleration Problems

J

JoshuaYoung

New Member
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?
 
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
 
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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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
 
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
 
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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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 !
 
GearNut said:
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.
Click to expand...
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
 
Do you think that can be the problem though? The bike accelerates at full speed then seems to choke! I took off the fuel hose from the carb and it flowed perfectly ! So I'm assuming its a flooded carb! Can a flooded carb or the float problem cause my issue I'm having?
 
Could also be fuel foaming in the bowl if the vibration is too great, or possibly the main jet is too rich causing spit-back & 4-stroking.
 
Is the jet apart of the carb? Basically I'm a noob to this stuff sorry! What should I buy to help me resolve my problem? A new carb? I know a guy who sells motor bike parts near me
 
Do not buy anything until you have thoroughly inspected the parts you have for problems/ adjustments needed.
Unless you like to throw money at problems until they go away.

Carburetors are very simple to work on. The hardest part is keeping the guts clean, and even that is not hard if you take precautions.
Cut out the side of a cardboard box and use it as a place mat on the table or work bench you are working over. This insures that no dirt or grit gets picked up by the parts when you lay them out. Use a cardboard egg crate to hold each part in order of dis-assembly. This makes it much easier to reassemble in the correct order and also insures that no parts were accidentally left out.
 
Which carb do you have?
There are videos on utube and some folks here have made how-to threads with good pictures.

Also, crassius brought up a good point: Does the engine vibrate alot?
Too much vibration will cause the fuel to foam inside the carb and negatively affect the carb's ability to properly meter the fuel.

Are you familiar with a 2 stroke engine 4 stroking? Do you know what it sounds like and the performance loss associated with it?
 
Is your engine mounted solidly to the frame? You're not trying to use rubber or something soft in the engine mounts are you? That will cause more vibration and can result in fuel foaming. Extreme vibrations can cause the problems you're having.

Tom
 
I was able to put a new carburetor on my bike. I rode it around and it still did the same thing. I noticed that the fuel filter was ziptied to my frame and the fuel was foaming/splashing a lot because of that! So I removed the zipties which allowed the fuel filter to flow freely and the splashing reduced inside the filter! It did feel like it helped after that but I still had the periodic slowing down of the bike when I had it at full throttle. Could it be anything else? I made sure that the fuel flows feely through the filter so that's why I haven't checked the petcock! But do you think it can be electrical problems or a throttle problem? Thanks and please let me know !
I'll include pics of the bike
 
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