The air/fuel mixture screw is drove in tight, I cant budge it, even with a screw driver and vice grips, someone must have drove it in there way over tight , If I am correct that is just a fine tuning for the jets, can I get away with re-jetting for a pipe and aftermarket air filter and not doing any adjustment for the air/fuel screw or do I need to drill that old one out and try to tap it and risk damaging the carb having to get a new carb, just for a fuel air screw, it idles and runs fine with the new jets, maybe a little rich, but better than lean, especially in Florida.
air/fuel mixture screw
- Thread starter Panzerman
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It maybe locked in place with a pin or set screw,what kind of car/carb is this?
I believe its a mikuni. its not locked in, its the type you turn in till seats and back out 1 and 1/2 turns, problem is, someone smashed it in tight and it isnt moving at all.
The air screw is to tune the low speed circuit. It works with the pilot jet. If the machine idles well and transitions smoothly from low speed to medium speed, don't sweat it. If you change your pilot jet, you may have a problem getting the carb to work right because you'll not have low speed adjustment.
When I modified my two stroke motorcycles, I had to increase the size of the pilot jets when I installed a larger main jets. With a freer breathing pipe, you need to flow more air and fuel. Too small of a pilot may not allow smooth transition to medium speed. The engine will run but you might have some hesitation when grabbing a handful of throttle.
You can try to do the mods to see how everything works. You might get lucky.
The pilot air screw isn't just a screw in a hole. There's a tiny coil spring and rubber O ring in there as well. You can pull the carb, drain all the fuel out of it and apply some localized heat to the pilot screw seat/hole. It might be enough to free it up.
When I modified my two stroke motorcycles, I had to increase the size of the pilot jets when I installed a larger main jets. With a freer breathing pipe, you need to flow more air and fuel. Too small of a pilot may not allow smooth transition to medium speed. The engine will run but you might have some hesitation when grabbing a handful of throttle.
You can try to do the mods to see how everything works. You might get lucky.
The pilot air screw isn't just a screw in a hole. There's a tiny coil spring and rubber O ring in there as well. You can pull the carb, drain all the fuel out of it and apply some localized heat to the pilot screw seat/hole. It might be enough to free it up.
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