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Kawasaki FB460V Carburetor

Kawasaki FB460V Carburetor Operation

In the choke or start position, the choke valve is closed, and the only air entering the engine enters through opening around the valve. As the starting device is operated to start the engine, the air pressure in the carburetor is reduced as air drawn into the engine.

Since the air passage is blocked by the choke valve, fuel is drawn from the main nozzle and from both idle fuel discharge ports and mixes with the air that passes through the throttle valve. This makes a very rich fuel mixture required to start a cold engine.

At idle a relatively small amount of fuel is required to operate the engine. The throttle is almost closed, shutting off the fuel supply from all except the one idle fuel discharge orifice, so that the suction created by the engine draws fuel only from that orifice. During intermediate operation, second and third orifices are uncovered as the throttle valve opens, and more fuel is allowed to mix with the air flowing into the engine.

During high speed operation, the throttle valve is fully opened. Air flows through the carburetor at high speed. The venturi, which decreases the air passage through carburetor, further accelerates the air flow. This high speed movement of the air decreases the air pressure, and fuel is drawn into the air stream through the main nozzle that opens into venturi, mining with the air in the air passage.

As the engine load increases, air is automatically bled into the main nozzle through the air jet located in the air horn. This allows fuel to be metered freely from the main nozzle and to be facilitated atomization.

General Specifications

Main Jet (FB460V-AS) - #112.5
Main Jet (FB460V-BS) - #115
Pilot Jet - #47.5 / #47.5
Pilot Screw (Turn out) - 1-1/8
Float Valve - 1.5 mm (0.059 in.)
Low Idle Speed - 1350 to 1450 rpm
Fast Idle Speed - 3275 to 3425 rpm
Float Level - Float parallel to carburetor body-to-bowl mating surface.

Kawasaki FB460V Carburetor Adjustment

Adjust idle mixture

Air cleaner must be assembled to engine. Turn idle mixture screw (B) in until it just seats, then back it out 1-1/8 turns. Do not turn the screw in too far. The pointed end of valve seat is susceptible to damage. Start and allow engine to warm. Move throttle lever on equipment to "IDLE POSITION".

Use a tachometer and adjust throttle stop screw (A) to obtain 1350 to 1450 rpm by turning it in or out while holding the end of the screw against carb body. Adjust idle mixture screw (B) by turning clockwise (lean) or counterclockwise (rich) to obtain the peak of idling. Turn idle mixture screw (B) back out 1/4 turn more. Use a tachometer and readjust throttle stop screw (A) to obtain and satisfy specified 1350 to 1450 rpm idling. Stop the engine.

Removal and Disassembly

Before removing for repair, check for signs of air leakage, or mounting gaskets that are loose, deteriorated, or otherwise damaged. Do not bent the links or stretch. Pull carb free, and gently twist carb. to free link rod. Remove governor link rod and link spring. Disassemble carb.

Kawasaki FB460V Carburetor Disassembly: 1 - Screw, 2 - Throttle valve, 3 - Screw, 4 - Choke valve, 5 - Screw, 6 - Spring, 7 - Spring, 8 - Pilot screw, 9 - Pilot jet, 10 - Drain screw, 11 - Spring, 12 - Spring, 13 - Ring, 14 - Ring, 15 - Gasket, 16 - Needle valve, 17 - Float pin, 18 - Clip, 19 - Float chamber, 20 - Choke shaft, 21 - Throttle shaft, 22 - Ring, 23 - Seal, 24 - Float, 25 - Main nozzle, 26 - Main jet, 27 - Washer, 28 - Bolt, 29 - Bleed pipe, 30 - Spring

Cleaning and Inspect

Place carb body and parts in PT503 cleaner or its equivalent. Do not put gaskets and plastic parts in cleaner. Parts should remain in cleaner for 1 or 2 hours. Remove and rinse with solvent. Rinse carb body in hot water to neutralize corrosive action of cleaner on aluminum. Dry parts with compressed air. Be sure all holes are open. Do not use rags or paper to dry parts. Lint may plug hole or passages.

Inspect carb body for damage. Flange sealing surfaces should be smooth and free of burrs and nicks. Replace gasket if necessary. Inspect pilot screw and drain screw for wear at the seating surface. Inspect for weak springs. Inspect main jet, bleed pipe, main nozzle and pilot screw for damage. Inspect inlet needle valve for wear or damage at the seating surface. Inspect clip for damage. Inspect the other parts of carburetor for wear, damage.

Assembly and Installation

Reassembly is the reverse of removal. Note the following points: Install main nozzle, bleed pipe, and main jet by turning clockwise into carburetor body. Do not over tighten screws. Install pilot screw (mixture screw) and spring finger tight. Install pilot jet screw by turning it clockwise into carb body.

Do not over tighten. Install float and float pin. Do not push on float or, inlet needle valve when adjusting float level. When carburetor is upside down, float surface (A) must be parallel to carburetor body (B). To adjust float surface angle, bend tang (C) with needle-nose pliers.

Install throttle linkages and choke linkage on carburetor. Install breather connector on intake pipe. Assembly gaskets, heat shield plate, carburetor, gasket and intake pipe. Install carb assembly on inlet pipe with through bolts.