Mine had the same problem. What I did was there should be a cover with 4 screws on the side of the carbourator, take it off and underneath should be a thin piece of rubber with a bubble(works as the fuel pump) and 2 little flaps(works as a check valve) often times the bubble gets a hole on it or just gets stretched and no longer supplys fuel the the engine, the solution: get a new peice, just take it into a lawn mower maintenance store they should hav 1. Other things to check would b to see if it it running too rich or too lean, there should be a screw with a spring on it some where on the carburetor to adjust the mixture. Also check to see if the clutch is still good.
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Clean your air filter- I had a chainsaw that did the same because the air filter was clogged with a mix of sawdust and oil (which I believe is called "bletch", or at least was by bus mechanics). Also, if you can, oil the appropriate moving parts in the clutch- if it's sticking it might engage and stay stuck in the engaged position, stalling the engine.
Other than that the usual advice about checking the mixture is probably the most sensible.
Let it warm up for some time, and clean the carb/fuel injector.
. heehee Too rich? Too lean? Which is it?
. If it is running too rich, you will usually get gray to black smoke out the exhaust and you may be able to smell raw gas.
. If no smoke, then you're probably too lean.
4 stroke engines shouldn't smoke
. They will if the mixture is too rich.
4 stroke engine with a wet sump take straight fuel. there is no mixing to be done. There is a 4 stroke engine which uses mixed fuel but it is primarily used in hand held small equipment (IE Stihls 4-mix motors used in their bigger back pack blowers and bigger string trimmer). Now if he is using a 2 stroke motor then yes it probably will smoke as all 2-stroke engines do because of the oil mixed in the gas. Although 2stroke engines how adays are under strict guidelines put forth by the EPA. The engines are running hotter and leaner than ever and also have new technologies coming forth (currently being implimented by Stihl and other manufacturers) that actually put a charge of fresh air before the fuel/air charge so that you loose less of the fuel/air mixture (scavenging loss)
. Fuel/air mix. If the F/A ratio is too high, the engine will smoke. Products of incomplete combustion.
sorry I had 2 stroke gas on the brain for some reason. yes if your engine is running rich, you will smoke black and you will also find your sparkplug quite black and sooty.
Maybe I was reffering to the comment of no smoke it's to lean. I forget. it's been a few days. But if it's running lean I would imagine the engine RPM's would surge or in the case of a major blockage in the main jet. wouldn't start at all. You're engine shouldn't be smoking any which way.
I also tend to go with a fuel problem. OTOH, if the magneto is mal/mis adjusted, the points need to be cleaned, and the condenser is older, a general tune-up is also in order.
The magneto has a specific clearance it needs to be from the flywheel magnets in order to create the voltage to spark across the spark plug gap. If the condenser is older, the time it takes to discharge slows, changing the time that the spark arrives at the spark plug, along with the opening of the throttle. If the points are older and pitted, this changes the timing as well.
If you still have the stock carburator on the engine, they are normally designed for single-speed operation, not for the variable conditions associated with go-karts/mini-bikes, making carburation a somewhat more critical area in regard to placing an engine under load throughout the RPM range of the motor.
Don't forget to check that there are no leaks between the carb and the intake, as this can cause the same problems as you describe.
Either way, check and clean your fuel delivery system, and give it a tune-up.
magneto air gap will very by engine, but usually a business card will do if you can't get the spec.
its clearly running to lean with fuel.quick test will prove it,get the engine running,take of the air filter whilst its running and the engine should run abit faster and the sound will change alot,then put the air filter back on and the engine noise will drop.if this happens then its getting to much fuel. whilst the air filter is off try putting ur foot on the gas it should be bale to cope better,but will still shutdown if you put ur foot down more.then u can just adjust the fuel with the air filter back on and adjust the fuel in untill the engine is quiet and that will be problem solved
The engine needs a tune-up. Giving it gas is running it too RICH, and all that fuel with not enough oxygen snuffs out the flame. You might not be running the correct octane fuel. Different octanes make the fuel burn at different speeds.
Check the air-filter, if its clogged it will not let enough air in, and will also cause this problem.
You might need to warm up the engine before it 'balances' the stoichiometric reaction. Let it idle for a while before giving it gas.
Just asking but how do you know it's not the other way and that the sudden opening of the carb is letting in a gust of air and leaning it out.
As far as I know the octane rating of fuels isn't how fast fuel burns. A quick google confirms it, As long as I have been taught, It is the fuels property to resist pre detonation.
But I do agree that you should let the engine warm up. Especially if you are trying to run your gokart now and if it's chilly outside. A lighter weight (5w-30) would be good for colder weather. Also try to ease on the gas, don't just stomp it to the floor. If the engine is surging (going up and down in RPM) I would go through the carb and clean it. pay careful attention to the emulsion tube (about 1" long with a bunch of little holes in it) and make sure it's clean.
I don't know - I'm rarely certain of anything. The evidence points to what I've experienced in the past of primarily dirty air cleaners, seconded by dirty carburetors.
I digress about fuel octane - I was misinformed. 'the speed at which it burns' vs ' the time it takes for it to asplode' was a poor phrasing :D Thanks for the clarification.
. We don't know. As L points out, we don't have enough info. But there have been some good guesses.
it's one or the other ;-)
Or the clutch is cutting in too early, or you have another transmission-fault? Assumptions have been made about your engine without any real information to support them - can you try this again and give us as much detail as possible?
. Sounds like a carburetor problem - probably leaning out when you open the throttle. Try opening the throttle very slowly. If that works, then you need to adjust or rebuild the carb.