How Most Carburetors Work and How to Properly Jet Them
Many people have no clue how to properly jet a carburetor it seems.
In fact, most people are to afraid to even take their carburetor apart, for fear of messing it up, and being stuck with an engine that runs horrible.
The funny thing is that once you understand the principles of how jetting and carbs actually work, then it becomes almost laughable at how basic most carburetors function, and how easy it is to adjust them.
So how exactly does a carburetor work? Almost every carb design works in the following manner: They have a bowl that is filled up with gas, which generally gets there from a gravity fed gas tank which is positioned above the carburetor.
When air passes into the intake of the engine, it flows through the carburetor first, and the air actually sucks gas up through the bowl of the carburetor as it rushes through.
The gas is sucked up from the bowl through the main jet and the pilot jet.
Now lets talk about how the jets affect the engine at certain RPM's, which will give you a far greater under standing of how to test your engine and see what you have to change as far as jet sizes.
For starters, when an engine is just idling, it is only pulling gas up through the pilot (or "slow") jet.
So if your engine won't idle well, start out by increasing or decreasing the size of the pilot jet.
At low to medium range RPM's, the needle jet is the main factor in the flow of gas.
If your engine bogs down when you are at about half throttle, then you need to adjust the needle jet (which is done by simply moving the position of the clip up or down).
As far as the main jet goes, this is arguably the most important out of all of the jets.
Luckily this one is pretty easy to adjust as well though.
The best way to find out how you will want to adjust your main jet, is to take your machine for a quick spin, and drive it at full throttle for about 5 to 10 seconds.
Now shut the engine off and take out the spark plug.
Look at the color of the spark plug; if it is brown (or tan), then you have the right size main jet.
However, if it is very black and seems to have soot on it, then the main jet is to rich, meaning that the engine is getting more fuel than it can even burn at higher RPM's.
So if this is the case, then you will need to put a bigger main jet size in your carburetor.
Well, that is pretty much it as far as adjusting the jets in most carburetors.
You see, it isn't so scary after all, once you know the basic principles of how carburetors work.
And now that you know the basics, you can now adjust your carburetor and get your engine running better than ever.
In fact, most people are to afraid to even take their carburetor apart, for fear of messing it up, and being stuck with an engine that runs horrible.
The funny thing is that once you understand the principles of how jetting and carbs actually work, then it becomes almost laughable at how basic most carburetors function, and how easy it is to adjust them.
So how exactly does a carburetor work? Almost every carb design works in the following manner: They have a bowl that is filled up with gas, which generally gets there from a gravity fed gas tank which is positioned above the carburetor.
When air passes into the intake of the engine, it flows through the carburetor first, and the air actually sucks gas up through the bowl of the carburetor as it rushes through.
The gas is sucked up from the bowl through the main jet and the pilot jet.
Now lets talk about how the jets affect the engine at certain RPM's, which will give you a far greater under standing of how to test your engine and see what you have to change as far as jet sizes.
For starters, when an engine is just idling, it is only pulling gas up through the pilot (or "slow") jet.
So if your engine won't idle well, start out by increasing or decreasing the size of the pilot jet.
At low to medium range RPM's, the needle jet is the main factor in the flow of gas.
If your engine bogs down when you are at about half throttle, then you need to adjust the needle jet (which is done by simply moving the position of the clip up or down).
As far as the main jet goes, this is arguably the most important out of all of the jets.
Luckily this one is pretty easy to adjust as well though.
The best way to find out how you will want to adjust your main jet, is to take your machine for a quick spin, and drive it at full throttle for about 5 to 10 seconds.
Now shut the engine off and take out the spark plug.
Look at the color of the spark plug; if it is brown (or tan), then you have the right size main jet.
However, if it is very black and seems to have soot on it, then the main jet is to rich, meaning that the engine is getting more fuel than it can even burn at higher RPM's.
So if this is the case, then you will need to put a bigger main jet size in your carburetor.
Well, that is pretty much it as far as adjusting the jets in most carburetors.
You see, it isn't so scary after all, once you know the basic principles of how carburetors work.
And now that you know the basics, you can now adjust your carburetor and get your engine running better than ever.
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