air screw?
- Thread starter Diabolic
- Start date
This a a previous Post from the forum. The Search Tab IS your friend!
Now, let's go look at the bottom end of the carb tuning.
In general, a TWO stroke carb has an Air Screw adjustment - which will be on the AIR FILTER SIDE of the carb's slide.
Most of the time, the air screw is set about 1-1/2 turns out from fully seated - this is a good base line starting point.
At first, adjust the Air Screw in 1/2 turn increments so you can see the difference. Then start being more finite by making 1/4 turn adjustments. You'll eventually get to where you only need to make adjustments in 1/8 turn increments.
Get your ride idling in neutral (warm it up fully first)
Quickly nail the throttle, going from idle to wide open in a smooth manner, but quick manner.
Just stabbing the throttle as fast as you can may cause enough disruption in the flow of the intake that the engine can't keep up - eventually, when the carb's tuned correctly, you should be able to nail it and have the engine react correctly. You'll see how this works as you tune the carb.
What does the engine do?
Does it hesitate and then rev up?
As it comes back down to idle, does it seem to hang at a higher idle for a minute and then settle down to normal idle?
If it does this you're Too Lean on the Air Screw adjusment. You need to richen it up by turning the Air Screw IN 1/2 turn and then repeat the test.
Adjust as necessary, repeating the test until you have a nice response.
Or
Does it sound like it bogs a bit?
As it comes back down to idle, does it seem to drop to a low idle (or even die) and then come back to normal?
If it does this, it's Too Rich. Turn the Air Screw out 1/2 turn.
Adjust as necessary, repeating the test until you have a nice response.
Remember: Adjust the Air Screw in 1/2 turn increments at first then fine tune with 1/4 turn and then 1/8 turn increments.
Repeat the proper adjustment until it responds without hesitation and drops back to idle without hanging or falling and then coming back up. Expect to do the bottom end adjustment at least three or four times before you get it right.
Go write down your findings
Now that you have a base line setting, try adjusting the air screw a full turn either way and see how the engine reacts. You'll soon see what the air screw does. Since you WROTE DOWN what you found, you'll be able to go right back to that adjustment point.
Now, let's go look at the bottom end of the carb tuning.
In general, a TWO stroke carb has an Air Screw adjustment - which will be on the AIR FILTER SIDE of the carb's slide.
Most of the time, the air screw is set about 1-1/2 turns out from fully seated - this is a good base line starting point.
At first, adjust the Air Screw in 1/2 turn increments so you can see the difference. Then start being more finite by making 1/4 turn adjustments. You'll eventually get to where you only need to make adjustments in 1/8 turn increments.
Get your ride idling in neutral (warm it up fully first)
Quickly nail the throttle, going from idle to wide open in a smooth manner, but quick manner.
Just stabbing the throttle as fast as you can may cause enough disruption in the flow of the intake that the engine can't keep up - eventually, when the carb's tuned correctly, you should be able to nail it and have the engine react correctly. You'll see how this works as you tune the carb.
What does the engine do?
Does it hesitate and then rev up?
As it comes back down to idle, does it seem to hang at a higher idle for a minute and then settle down to normal idle?
If it does this you're Too Lean on the Air Screw adjusment. You need to richen it up by turning the Air Screw IN 1/2 turn and then repeat the test.
Adjust as necessary, repeating the test until you have a nice response.
Or
Does it sound like it bogs a bit?
As it comes back down to idle, does it seem to drop to a low idle (or even die) and then come back to normal?
If it does this, it's Too Rich. Turn the Air Screw out 1/2 turn.
Adjust as necessary, repeating the test until you have a nice response.
Remember: Adjust the Air Screw in 1/2 turn increments at first then fine tune with 1/4 turn and then 1/8 turn increments.
Repeat the proper adjustment until it responds without hesitation and drops back to idle without hanging or falling and then coming back up. Expect to do the bottom end adjustment at least three or four times before you get it right.
Go write down your findings
Now that you have a base line setting, try adjusting the air screw a full turn either way and see how the engine reacts. You'll soon see what the air screw does. Since you WROTE DOWN what you found, you'll be able to go right back to that adjustment point.
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The air screw does as the description sugguests, it adds air to the pilot to allow the idle to be adjusted.
