As used on Mikuni carburetors and their clones, the cold-enrichment circuit works in conjunction with a lever-operated plunger and a closed throttle to deliver a rich mixture for starting (Fig. 4-35). Intake vacuum draws fuel from the bowl, which then passes through the starting jet into a small mixing chamber for aeration. Raising the brass [...]
Air flow past the nearly closed slide does not generate sufficient vacuum for the needle jet to flow at between 0 and 1/4 throttle. Fuel enters the carburetor bore through the idle, or pilot, jet and enters the main bore through the idle discharge port, located just aft of the slide valve. While single-port models [...]
At 1/4 to 3/4 throttle, the clearance between the needle and needle jet controls fuel delivery with some assistance from the air bled and the cutaway milled on the leading edge of the slide. A clip secures the grooved needle to the slide. Raising the needle richens the mixture by increasing flow through the needle [...]
Slide carburetors are used on motorcycles, water craft, and other applications where customers insist upon performance. At WOT, the slide retracts clear of the bore, offering no obstruction to air flow. The slide works in conjunction with a tapered needle to vary both air and fuel passing through the instrument, a configuration that smoothes the [...]
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