The idle air screw is "bottomed out" when you can't turn it IN any more. Turn it in GENTLY as you do not want to damage the tip of the idle air screw. It is a precise metering device and deforming the tip by over tightening it will cause you carb adjustment frustration.
So, turn it IN until is stops. (gently) Then turn it OUT 1 1/2 turns to start. Once the engine is warmed up adjust the screw IN and OUT 1/4 turn at a time looking for your MAX RPM. Once you find the best RPM, try turning the screw 1/8 of a turn to obtain the absolute best RPM.
Once that is achieved, reset your idle RPM by adjusting the throttle position screw to your desired RPM.
While adjusting the idle air mix screw, if you find the best RPM is with the screw turned all the way IN, you need to go down 1 jet size on the pilot circuit. If you find the best idle is with 3 full turns of the screw OUT or more, you need to go UP 1 or more jets on the pilot circuit.
And I will agree with Tom on your intake manifold Q. However, I will also add if you want some performance, match up your intake manifold and head ports. Also clean up any casting slag inside the opening. If the air flows smoothly into the head with no obstructions you should see a slight gain in performance for FREE.
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My Yerban assault vehicle: 2.2mm stroker crank, 62mm Nikasil cyl, Taida large vavle head, American made valve springs, ported intake manifold, TM 28mm carb, stock CDI, Bando coil, TK exhaust, stock CVT except for the 14g sliders, 13/40 internal gears, 16T drive, 31T axle sprocket, 22" rear tires, and ONE BIG POTATO CANNON mounted on top..........
Last edited by xlint89; 01-01-2017 at 08:39 AM.
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