Question on air/fuel setting
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Question on air/fuel setting
Had this in the Tech section without a lot of response. Thought I'd throw it out here and see if i could get a better response.
I was adjusting the air/fuel mixture screw and I can turn it all the way in to seat without the motor starting to stumble. Is this a sign of an intake leak or is it possible for little change when needle is seated.
It was suggested that the lowspeed jet may be too big.
I was adjusting the air/fuel mixture screw and I can turn it all the way in to seat without the motor starting to stumble. Is this a sign of an intake leak or is it possible for little change when needle is seated.
It was suggested that the lowspeed jet may be too big.
Tourer
Joined: Feb 2006
Posts: 429
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From: Southampton, Pa
RE: Question on air/fuel setting
If you turn the idle air screw on the bottom of a CV carb in and it does not effect the idle then you probibly have the idle screw up by the throttle shaft too far open and need to close it down. To set the idle on the CV carb without a tach you turn the idle screw in to give it a fast idle then turn the idle air screw on the bottom in to where it bottoms out (gently), then slowly turn the idle screw in until it stumbles or dies, then turn the idle air screw out about 2 turns for a good starting point, restart and take the bike for a ride and see if it coughs when you go to take off, if it does then you need to turn the idle air screw out more keep going at 1/4 turn increments until it stops coughing when you take off. This needs to be done with the engine at operating temps without using the enrichiner (choke). If you get to 4 or more turns it's recomended that you go up in jet size, if you have to turn the screw in to get it from fouling the plugs or black smoking then you need to go down in jet size. A good rule of thumb is to have a jet that lets you run with the idle air screw to be between 1 and 3 turns out. Hope this helps. This is for the CV Carb if you have a S&S or Mikuni carb they get adjusted differently. By the way if when you turn out the idle screw and it doesn't stumble or die then you need to check the rubbers on the intake manifold and see if you have a leak.
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