Post by dirtyolman on May 12, 2012 15:47:20 GMT -5
In recent months, I have had to change the tune on my 2 stroke, and when I moved, I had to change it again. This time around, it became very difficult, and I just couldn't get it right, couldn't keep it from running rich was the main issue. You can try changing the stock airbox for an air filter but risk running my 2 stroke lean, not what I wanted.
My 2 stroke is especially finicky about air flow, and a while back, I tried a little experiment that gave me the best results I ever got without having to modify the airbox itself.
What I call it is "airflow tuning", and it's simple to do and it may require having a backup part. I will divulge this little experiment verbatim,so it should be easy to understand. This works for the chinese stock airbox only, although this method could be used on other airboxes, but use caution when doing it.
I live in Florida, I recently moved from northwest to central fla, this move didn't seem so significant to me, but my 2 stroke scooter didn't like it. my scooter woudn't go over 25 MPH, no matter how I adjusted the air/fuel mixture screw, it constantly ran rich, and the result was the plug you see below.
The plug was black with soot & carbon build-up, and no kind of carbueretor adjustment wasn't going to fix this, and removing the airbox, would only make it run way too lean, destroying the motor.
So how did I solve this problem......well...check this out!
The stock airbox has an airflow that goes from the middle to the top, the amount of airflow is influenced mainly by air density (or sea level density). Air density plays a big role in how air is circulated through the airbox itself, even before it goes into the carbueretor, no matter what kind of filter element you use. The longer the path of airflow, the harder the engine has to work to use that air.
The picture below illustrates the path the airflow would typically have to take, this is critical to know at this point, as this will be the core of the problem.
The intake tube is what we are going to concentrate on from this point, this tube looks innocent enough, but air has to be pulled through this little tube that is narrow in diameter, into a bigger tube, and this is where the problem actually starts. Since air has to go at least 2 1/2 inches into the airbox, especially with dense sea level air, it has to travel a longer path, this retards air flow, and causes excess fuel to be used up and wasted on low speeds, this results in really bad gas mileage, carbon buildup, and poor performance.
The picture below is a clear example of poor airflow.
This spark plug is the first part of a plug chop to determine if air flow could be the cause, the carbueretor is adjusted properly, but not enough air is being taken in. I am getting poor gas mileage, and performance is non existent.
This intake tube could be a problem, with it being so long, it's taking alot more work for air to circulate through the airbox, causing over exhirtion to the motor.
My idea was to shorten the path the air had to circulate, the air filter covers the inside of airbox thoroughly, so air can liteally be sent any path because it still gets filtered, but it doesn't have to go the 2 1/2 inches, instead, a shorter path will still be filtered, and air can be sent to the carbueretor quicker.
I cut the intake tube the way you see pictured below (I cut 2 inches off), and the second plug used for the plug chop was used, and this is the final result of the plug chop with a shorter intake pipe.
The plug has a very nice cream coffee look to it indicating that there is enough air flowing through the airbox, and is mixing with the fuel proportionately, resulting in optimal performance, gas mileage, and an absence of carbon buildup
It's that simple!!!
So forget all these tuning problems you're having, if your motor is running rich and it just won't tune right, this could be the solution to all of your problems, it's a simple fix, and a cheap part to replace, you may even have an intake tube that you can gradually cut to obtain the airflow you need.
My 2 stroke is especially finicky about air flow, and a while back, I tried a little experiment that gave me the best results I ever got without having to modify the airbox itself.
What I call it is "airflow tuning", and it's simple to do and it may require having a backup part. I will divulge this little experiment verbatim,so it should be easy to understand. This works for the chinese stock airbox only, although this method could be used on other airboxes, but use caution when doing it.
I live in Florida, I recently moved from northwest to central fla, this move didn't seem so significant to me, but my 2 stroke scooter didn't like it. my scooter woudn't go over 25 MPH, no matter how I adjusted the air/fuel mixture screw, it constantly ran rich, and the result was the plug you see below.
The plug was black with soot & carbon build-up, and no kind of carbueretor adjustment wasn't going to fix this, and removing the airbox, would only make it run way too lean, destroying the motor.
So how did I solve this problem......well...check this out!
The stock airbox has an airflow that goes from the middle to the top, the amount of airflow is influenced mainly by air density (or sea level density). Air density plays a big role in how air is circulated through the airbox itself, even before it goes into the carbueretor, no matter what kind of filter element you use. The longer the path of airflow, the harder the engine has to work to use that air.
The picture below illustrates the path the airflow would typically have to take, this is critical to know at this point, as this will be the core of the problem.
The intake tube is what we are going to concentrate on from this point, this tube looks innocent enough, but air has to be pulled through this little tube that is narrow in diameter, into a bigger tube, and this is where the problem actually starts. Since air has to go at least 2 1/2 inches into the airbox, especially with dense sea level air, it has to travel a longer path, this retards air flow, and causes excess fuel to be used up and wasted on low speeds, this results in really bad gas mileage, carbon buildup, and poor performance.
The picture below is a clear example of poor airflow.
This spark plug is the first part of a plug chop to determine if air flow could be the cause, the carbueretor is adjusted properly, but not enough air is being taken in. I am getting poor gas mileage, and performance is non existent.
This intake tube could be a problem, with it being so long, it's taking alot more work for air to circulate through the airbox, causing over exhirtion to the motor.
My idea was to shorten the path the air had to circulate, the air filter covers the inside of airbox thoroughly, so air can liteally be sent any path because it still gets filtered, but it doesn't have to go the 2 1/2 inches, instead, a shorter path will still be filtered, and air can be sent to the carbueretor quicker.
I cut the intake tube the way you see pictured below (I cut 2 inches off), and the second plug used for the plug chop was used, and this is the final result of the plug chop with a shorter intake pipe.
The plug has a very nice cream coffee look to it indicating that there is enough air flowing through the airbox, and is mixing with the fuel proportionately, resulting in optimal performance, gas mileage, and an absence of carbon buildup
It's that simple!!!
So forget all these tuning problems you're having, if your motor is running rich and it just won't tune right, this could be the solution to all of your problems, it's a simple fix, and a cheap part to replace, you may even have an intake tube that you can gradually cut to obtain the airflow you need.