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1) There's no choke. Only an enrichment device used for starting. Lift it up and rotate slightly to enrich the mixture and down to shut it off. Use to prime engine with ignition off. Can be left on temporarily with some open trottle, iginition on, during warmup.
2) Start with idle mixture set One and One half turns out from closed. And throttle sjustment screw out 1/2 turn. Do no over tighten to find closed position.
3) Start engine and run until oil and engine is warmed-up, and adjust throttle stop until you get 1000rpms.
4) Adjust idle mixture both in and out until engine begins to die. Put the idle mixture screw between those two points.
If the idle mixture screw has no effect, then your intermediate jet (IJ) may be to lean (small) or rich (big). If turrning the idle mixture screw in (lean) doesn't cause the engine to die, you have to big of a IJ. Stock IJ is a .028. Jets are avialable in ).015 increments. (25 being the lowest). Carb bowl must be removed to change IJ.
If you have an air leak, then the engine will run poorly at idle and higher
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