How to Clean a Carburetor on a Ninja 250

The Ninja 250R is one of Kawasaki's best selling motorcycles and has been in continuous production since 1986. The Ninja 250R remained largely unchanged since its introduction until it received its first redesign in 2007. While there are some differences between both variations, they both use a pair of carburetors to feed the 249 cc parallel-twin engine. These carburetors can clog as gasoline has a tendency to degrade over time, reducing to a thick, sticky sludge that prevents air and fuel from passing through the carburetors' jets and passages. The carburetors must be removed and disassembled to completely remove sludge buildup.

Things You'll Need

• Allen wrench, 5 mm
• Flat-head screwdriver
• Socket, 10 mm
• Socket wrench
• Pliers
• Phillips-head screwdriver
• Open-end wrench, 10 mm
• Gas can
• Container
• Carburetor cleaning solution
• Punch
• Socket, 12 mm
• Box-end wrench, 8 mm
• Aerosol carburetor cleaner
• Air compressor
• Torque wrench
• Gloves
• Protective eyewear

Instructions

1. Lift the motorcycle onto its center stand and let the engine cool for at least one hour.

2. Remove the seat using the keyed release latch. Pull the side covers, located under the seat, off the motorcycle's frame. Remove the side fairing panels using a 5 mm Allen wrench.

3. Turn the fuel valve located under the left side of the fuel tank to the "on" position, using the valve lever or a flat-head screwdriver. Pull the fuel and vacuum hose off the side and rear of the fuel valve using pliers. Unscrew the fuel tank mounting bolts using a 10 mm socket and a socket wrench. Lift the fuel tank off the motorcycle, then unplug the fuel level gauge connectors from the bottom of the tank.

4. Disconnect the diodes and the headlight relay from the top of the battery cover, located between the seat rails. Remove the battery cover using a Phillips-head screwdriver. Disconnect the negative cable, followed by the positive cable, from the battery, using a Phillips-head screwdriver. Lift the battery out of the battery box. Remove the screws from the bottom and sides of the battery box, then lift the box out of the motorcycle's frame.

5. Unscrew the mounting bolts from the top of the air box using a 5 mm Allen wrench. Loosen the clamps attaching the air box ducts to the carburetor and the carburetors to the engine using a Phillips-head screwdriver. Push the air box ducts off the carburetor inlets, then pull the carburetors off the engine.

6. Loosen the choke cable holder screw, located at the top of the carburetor assembly, using a Phillips-head screwdriver. Pull the choke cable end fitting out of the choke arm. Loosen the throttle cable locknuts, located on the right side of the carburetor assembly, using a 10 mm open-end wrench. Turn the throttle cable adjusters clockwise to loosen the cables, then pull the cable ends out of the throttle valve. Unbolt the idle adjustment knob bracket from the left side of the motorcycle's frame using a 10 mm socket.

7. Loosen the float bowl drain screws, located on the bottom left side of both carburetors, using a flat-head screwdriver. Drain the remaining gasoline into a gas can, then tighten the drain screws. Remove the float chambers using a Phillips-head screwdriver, then place the chambers in a container filled with a carburetor cleaning solution.

8. Remove the floats and float pins from the bottom of the carburetors using a punch. Pull the needle valves out from the valve seats above the floats. Unscrew the float seat using a 12 mm socket. Unscrew the main jet from the needle jet holder at the center of the carburetors, using a flat-head screwdriver. Unscrew the needle jet holder using an 8 mm box-end wrench. Unscrew the pilot jet, located next to the needle jet holder, using a flat-head screwdriver. Place the main and pilot jets, as well as the needle jet holder, into the carburetor cleaning solution.

9. Remove the top caps from both carburetors using a Phillips-head screwdriver. Pull the diaphragm valve, valve spring and the jet needle out from the tops of the carburetors. Push the jet needles out of the diaphragm valves, then place them in the carburetor cleaning solution.

10. Remove the air cut valve from the left side of the carburetors using a Phillips-head screwdriver. Pull the air hoses off the top and bottom of the air cut valve.

11. Spray the fuel passages on the bottom of the carburetors as well as the air passages cut into the carburetor inlets with an aerosol carburetor cleaner. Clear any debris trapped in the passages using compressed air. Blow compressed air through the fuel hoses. Repeat until air easily can pass through all of the carburetor passages and fuel hoses.

12. Remove the jets, jet needle holder and needle valve seat from the carburetor cleaning solution. Blow compressed air through the holes at the center of the jets, needle holder and valve seat to remove obstructions. Hold the jets up to a bright light to ensure the jet passages are free of debris. Blow dry the float chambers and jet needles with compressed air.

13. Reinstall the needle valve seats and valve needles into both carburetors, followed by the floats and float pins. Screw the needle jet holders, main jets and pilot jets into place. Reinstall the float chambers.

14. Push the jet needles into the diaphragm valves, then slide the valves into the carburetors. Push the diaphragm springs down and reinstall the top caps onto both carburetors. Reinstall the air cut valve onto the left side of the carburetors, then push the air hoses onto the air cut valve.

15. Reinstall the throttle and choke cables, then push the carburetors into the engine's carburetor holders. Push the air box ducts over the carburetor inlets, then tighten the clamps on the front and rear of the carburetors. Screw the air box mounting bolts into place. Mount the idle adjustment knob bracket onto the motorcycle's frame.

16. Reinstall the battery box and battery onto the motorcycle. Connect the positive cable, followed by the negative cable, to the battery. Reinstall the battery cover, then reconnect the diodes and headlight relay.

17. Reinstall the fuel tank onto the motorcycle and reconnect the fuel and vacuum hose onto the fuel valve. Tighten the fuel tank mounting bolts to 7.6 foot-pounds using a torque wrench. Reinstall the side fairing panels and the seat onto the motorcycle.

Tips & Warnings

• Extremely flammable vapors will be released by the gasoline held in the carburetors. Do not smoke or work near an open flame while servicing your Ninja 250's carburetors.

• Most carburetor cleaning solutions are solvent-based and can cause severe skin irritation. Wear gloves and protective eyewear while working with carburetor cleaning solutions to avoid injury.

References

• 2007 Kawasaki Ninja 250R Motorcycle Service Manual; Kawasaki Heavy Industries
• 2003 Kawasaki Ninja 250R Motorcycle Service Manual; Kawasaki Heavy Industries