How to Rebuild the Yamaha YTM 225DX's Carburetorby William Machin
Rebuilding the carburetor on a Yamaha YTM 225DX three-wheel ATV is as easy as it gets. The simplicity of the Mikuni VM-24 carburetor affords novice mechanics an introduction into basic carburetor functions. Removing the unit for rebuilding is a matter of disconnecting the fuel line and throttle cable, and removing the air cleaner before taking the carburetor off the intake manifold. Rebuild the Yamaha YTM 225DX carburetor using the parts from a rebuild kit.
Disassembly and Cleaning
Hold the carburetor over a utility pan. Loosen and remove the brass drain plug at the bottom of the fuel bowl with a metric wrench. Drain the gasoline from the bowl into the pan. Place the drain plug in a carburetor cleaner basket.
Turn the carburetor over. Remove four screws at the fuel bowl with a screwdriver. Take the bowl off the carburetor body and discard the gasket. Put the fuel bowl in the cleaner basket.
Take the twin float off the base of the carburetor and place it in the cleaner basket. Loosen and remove the needle valve assembly at the underside of the carburetor with a metric wrench. Discard the brass needle valve and place the assembly in the basket.
Loosen and remove the brass pilot jet and larger main jet from the underside of the carburetor body with a screwdriver. Discard both jets.
Turn the carburetor upright. Loosen and remove the carburetor cap by hand. Pull the throttle-return spring, throttle-side piston and the long jet needle out of the carburetor by hand. Place the parts in the cleaner basket.
Remove the pilot-air screw and the idle adjuster screw from the side of the carburetor with the screwdriver. Put both screws and the springs in the basket. Place the carburetor body in the basket.
Put on latex gloves. Immerse the cleaner basket in the can of carburetor cleaner for 30 minutes. Rinse the parts with fresh water and dry each with shop rags.
Install the pilot-air and idle adjuster screws and stem springs into the side of the carburetor with the screwdriver. Insert the jet needle, throttle-slide piston and the throttle return spring into the top of the carburetor.
Place the new cap washer from the rebuild kit on the carburetor and screw the carburetor cap on by hand.
Turn the carburetor over. Install the new brass pilot jet and main jet into the underside of the carburetor body with the screwdriver. Install the needle valve assembly and new needle valve from the kit into the base of the carburetor and tighten the assembly with the screwdriver.
Press the cleaned twin float in position at the underside of the carburetor by hand. Put the bowl gasket from the kit on the rim of the fuel bowl. Attach the bowl to the carburetor with the saved screws. Put the new ring gasket on the face of the carburetor flange before installing the carburetor onto the intake manifold on the engine.
- Refer to the instructions and include any new washers, clips or springs provided in the rebuild kit.
- Remove excessive lacquer deposits with spray cleaner and steel wool.
- Replace the air filter cartridge and install a new fuel filter.
Things You'll Need
- Mikuni VM-24 carburetor kit
- Utility pan
- Metric wrenches
- Carburetor cleaner basket
- Latex gloves
- Carburetor cleaner
- Shop rags
William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.