Mikuni carburetor  are a popular upgrade for motorcycles. They have bigger inlets than standard CV carburetors and allow for a better air/fuel ratio, giving the engine more power. They are easy to install, but require careful jetting and adjustment to get the optimum performance. A trained mechanic should perform this task.

Mikunis are round-slide carburetors that were originally mounted on two-stroke, Japanese motorcycles. They quickly gained popularity among racing tuners and mechanics for their reliability and ease of tuning and maintenance. They are now used in a variety of applications including ATV’s, snowmobiles and gas powered equipment like generators and welders.

“Fine-Tuning Power: A Deep Dive into Mikuni Jet Kits for Optimal Motorcycle Performance

There are four major circuits within the mikuni carburetor that effect fuel delivery to the engine. Each one of these circuits works in conjunction with the other to provide optimal fuel delivery.

First lets start with the Fuel Bowl. Fuel flows from the bike’s fuel tank past the petcock into the carburetor. From there it flows through a couple of 90-degree turns past the float bowl vent and into the carburetor’s fuel inlet.

Once in the carburetor, the fuel flows through an emulsion tube where it is broken into tiny, microscopic-sized particles that are mixed with air in a specific ratio. This fuel vapor mixture then passes into the carburetor’s main jet where it is delivered to the engine.

The choke circuit, or enricher starting system as Mikuni refers to it, is a separate passage that allows more fuel to pass through to the carburetor’s main jet during startup. This richer mixture makes the carburetor ideal for cold starts and provides a quicker, smoother throttle response. The throttle slide must be kept closed during startup to prevent defeating the choke circuit.