Mikuni carburetor is a popular choice for performance motorcycles and ATV’s. They are easy to tune and offer a good mix of performance and reliability. These round slide, multi-circuit carbs are available in a number of sizes that allow you to fine tune the fuel mixture for a variety of engines and conditions.

VM Series Mikuni carburetors have been the performance standard for motocross racing, enduro and trail riding as well as flat track racing on both 2-stroke and 4-stroke engines. These carburetors are also found on street bikes, dirtbikes, go-karts, and other gas powered equipment such as generators and welders.

When the engine is at idle, a mikuni carburetor draws the air and fuel through a large venturi that efficiently delivers the fuel into the main circuit. A large needle jet then meters the proper amount of fuel to the throttle slides based on a set of predetermined criteria. Changing the needle jet or opening the mixture screw will alter these criteria and change the fuel/air ratio at various throttle settings.

Understanding Cartridge Heaters: Applications and Advantages

One of the most common mistakes is to use the wrong needle jet size. There are two common types of mikuni jets – the large round and the long hex. The hex jet is longer and has a larger diameter inlet, while the large round has a smaller diameter inlet. Make sure you have the correct size before installing it.

Before doing any work on a mikuni carburetor it is always a good idea to remove the needle and seat assembly from the carb and clean all parts thoroughly with carb cleaner. There is a very delicate surface where the needle and seat meet that is important to be as smooth and free of debris as possible. If the needle and seat are not as smooth as possible, they can leak fuel.

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