Remember the three important things your engine needs to start and run well:
1. Spark. You need a eletrical spark to start the motor.
2. Gasoline. You need the proper amount of gasoline to mix with air in the right ratio to form a combustible fuel.
3. Air. Your engine needs to be sucking in air and pushing out air properly in order to mix with gasoline to form a combustible fuel.
You have all three of those things and you have a running motor.
Your missing one of those three.
First thing to do...
1. SPARK!
A new spark plug is always a good thing to try. When a spark plug fouls it will simply stop working. Like somebody flipped a switch. Putting a new spark plug will help tremendously if that is the case.
I always carry a new spark plug with me whenever I ride 2-stroke bikes. It's kinda stupid not to as it's cheap, easy to replace (with the proper tool), and small to carry.
2-strokes foul plugs. It should happen rarely and only when the plug is worn out if the bike is properly tuned, but most people will foul plugs time to time. 4-strokes tend to not have as much issues and on automobiles you have multiple cylinders.
When you replace a spark plug you can check two more things:
A. See if it is getting gasoline. Try running it a bit before changing the spark plug. When you pull it out and you cranked it over a bunch of times without starting then it should be wet and you should be able to smell the gasoline very strong out of the spark plug hole.
It's not a very good test, but it's easy if you remember.
B. See if it is getting spark.
The idea is that if you put the spark plug into the spark plug boot, but don't plug the spark plug back into the hole first you can place the tip of the plug against the engine block and turn it over and you should see the spark. It should be fairly bright and blue, but you'll have a hard time in direct sunlight.
But that's hard on these bikes since you need to be pedaling it first.
You'll probably shock yourself and it's painful and scary. But it won't damage you much.
I'd just try it with the new spark plug first without testing the spark, but it's something to keep in mind.
If your not getting a spark then it's probably a lose connection somewhere. Trace the wires, make sure that they are firmly in place.
Connections come loose, they corrode and form to much resistance. Your kill switch can be broken and be killing your motor even when your not pressing it. The spark plug can be lose. The spark plug wire can be lose. The CDI black box can be bad.
B. GASOLINE!
If replacing the spark plug does not work and you know your getting a strong spark then it's time to check the fuel.
It sounds like your engine is running very rich or you have water in the float bowl.
I'd check:
* Make sure that you have gasoline,
* make sure that the filter is not plugged up, (fuel flows through the fuel line.
* Make sure that the float bowl is filling up with gasoline.
* Make sure that it's not filling up too far with gasoline and flooding the motor. (that your float bowl floats are working...)
I think that it is likely that you have water in your float bowl.
Water and gasoline don't mix. But... water can get into the fuel tank. It doesn't take much. Riding through sprinklers or even just high humidity can do it. The gas caps on these things are pretty lousy.
When water gets in the motor will run very well. The water gets shaken up into particulates... like tiny bubbles of water in your gasoline. This gets sucked into your motor and evaporates very rapidly and doesn't usually cause problems immediately.
But what happens is that when you turn off the motor and let it sit then the water collects at the bottom of the fuel bowl on the carb. The water bubbles collect and form a puddle that sit underneath the main jet. This will allow some gasoline to get past occasionally so you can get it to sort of run, but it will die if you try to give it lots of gas or if your trying to go up a hill or something like that.
Enough water will simply stop the motor running at all.
To check for water requires a visual inspection of the float bowl with gasoline in it. Take the carb off, take the bowl off and then look for a puddle or bubbles underneath the gasoline. Thats water.
If you have water then clean out the bowl, empty out the gas tank, and put fresh gasoline in. Add alcohol to soak up the remaining water. Alcohol binds with water, but gasoline doesn't. The alcohol binds with the water and eventually gets sucked into your motor and burns away harmlessly.
Ethanol gasoline is helpful. Also you should buy and use anti-gas line freezing chemicals at the auto part store. That is mostly alcohol.
Stuff like Iso-heet. Use as indicated by the bottle. Don't overdo it.
If it's not water then it's likely your jets are clogged and fuel isn't getting through to the engine.
Once you got the float bowl removed take out the jet. Inspect it and make sure that it's clear from debris. That's the smallest opening and if it's clogged it's probably going to be that. Just don't damage it when trying to remove it.
Also the idle circuit is probably separate from the main jet. So if you get the main jet cleaned out and it's working fine, but it's not idling right then the idle jet/circuit may be clogged also.
I am not that familiar with these types of carbs so I don't know for certain.
Once you get the jet cleaned out put a fuel line filter to stop other debris from causing problems. The gas tanks in these kits are very dirty and you will probably get issues if you don't put a proper fuel filter in place.
These are the most likely issues.
C AIR!
Air is very simple on these motors. Check the air filter, check the exhaust. If they are clogged then that will cause problems. There is no valve train like on 4-strokes so it's easy to troubleshoot this issue.
