Mikuni Carburetor; Function - Polaris 2007 Two Stroke Service Manual

Float/Needle & Seat Assembly (H): The float/needle & seat are
sold as an assembly and cannot be replaced as individual
components. The float level is pre-set in the molding and cannot
be adjusted.
WARNING
DO NOT pressurize the fuel system by forcing compressed
air through the fuel tank. Forcing air through the needle and
seat will cause damage and the float/needle & seat assembly
will have to be replaced.
Carburetor Synchronization: Remove the top caps on all
carburetors. In the body of the carburetors, there is a Phillips
head set screw (I) that connects the slide lever to the throttle
lever shaft. The carburetor with the fixed set screw is the base
carburetor (middle carburetor on triples, PTO carburetor on
twins) and the remaining carbs are synchronized to it.
Carburetor synchronization is measured at wide open throttle.
Open the throttle to wide open. The bottom of the slide should
be flush with the top of the throttle bore. If it is not flush, locate
the wide open throttle stop screw (J) and turn it until the base
carburetor is set flush. Loosen the Phillips head set screw in the
remaining carburetor(s). Turn the adjusting nut (K) that
surrounds the set screw until the throttle slide is set the same as
the base carburetor. Tighten all set screws and replace the top
caps making sure gaskets are properly positioned.

MIKUNI CARBURETOR

Function

The function of a carburetor is to produce a combustible air/fuel
mixture by breaking fuel into tiny particles in the form of vapor,
to mix the fuel with air in a proper ratio, and to deliver the
mixture to the engine. A proper ratio means an ideal air/fuel
mixture which can burn without leaving an excess of fuel or air.
Whether the proper mixture ratio is maintained or not is the key
to efficient engine operation.
The engine of a vehicle is operated under a wide range of
conditions, from idling with the throttle valve remaining almost
closed, to full load or maximum output with the throttle valve
fully opened. In order to meet the requirements for the proper
mixture ratio under these varying conditions, a low speed fuel
system, or pilot system, and a main fuel system are provided in
Mikuni type carburetors. The Mikuni carburetor has varying
operations depending upon varying driving conditions. It is
constructed of a float system, pilot system, main system, and
starter system or initial starting device.
FUEL DELIVERY
4.7
4