How to Clean Old Motorcycle Carburetors

Although it's not the first thing you'd think of when it's time to clean your carbs, lemon juice is one of the most effective cleaning agents around.

Restoring an older motorcycle from a state of disrepair will almost always require a carburetor cleaning. While there are several cleaning agents available from your local auto parts store, most of these products are made from toxic compounds that can make using and disposing of these products extremely difficult. However, one of the best cleaning solutions for an old, gunked-up carburetor is in our own kitchen. Lemon juice, containing powerful citric acid, has been used to great success by motorcycle mechanics the world over, allowing a cheap and efficient method to get your vintage bike back on the road.

Things You'll Need

• Screwdrivers
• Container
• Plastic bags
• Lemon juice
• Water
• Large pot
• Electric hot plate
• Toothbrush
• Air compressor
• Wire
• Gaskets

Instructions

1. Remove the carburetor from the motorcycle. Disconnect the fuel lines from the carburetor, allowing any fuel left in the lines to drain into a container. Unscrew any hose clamps that secure the air box to the carburetor and the carburetor to the motor. Push the air box boots away from the carburetor and pull the carburetor off of the motor.

2. Set the carburetors onto a clean work area. Remove the float bowl drain screws from the bottom of the carburetor with a flat screwdriver. Allow any remaining fuel in the float bowls to drain into a container. Set the float bowl drain screws aside.

3. Disassemble the carburetors, removing the float bowls, floats, jets, needles, and diaphragms. Place these in individual plastic bags to prevent them from being misplaced.

4. Prepare a cleaning solution of 6 parts water to 1 part lemon juice in a large metal pot. Heat the solution to a rolling boil with an electric hot plate. Once the solution is boiling, place the disassembled carburetor assembly and float bowls into the pot and allow it to soak for thirty minutes.

5. Pull the carburetor assembly and float bowls from the lemon solution with a pair of tongs and rinse thoroughly with clean water. Using a toothbrush, scrub the inner and outer surfaces of the carburetors to remove any remaining debris or buildup. Rinse again with fresh, clean water. Dry the carburetor and float bowls by blowing compressed air through the carburetor body and fuel passages.

6. Clean the carburetor jets with compressed air to clear the passages. Remove any remaining debris with a thin piece of wire.

7. Reassemble the carburetors, installing the jets, needles and floats. Replace any damaged or worn gaskets.

8. Install the carburetor on the motorcycle, tightening any hose clamps to prevent air leaks. Reattach the fuel lines to the carburetor.

Tips & Warnings

• Replace the fuel in the motorcycle's gas tank prior to reinstalling the carburetors. Old fuel may have deteriorated or may contain debris that will clog the carburetor's jets and fuel passages.

• Using a lemon juice solution may create a dull gray appearance on the carburetor's aluminum bodies. This will not harm the operation of the carburetor and can be polished away, if desired.

• Soak the carburetors outdoors, if possible. The cleaning solution will not create harmful fumes, but will emit an unpleasant odor that may be difficult to remove indoors.

References

• "The Professional Motorcycle Repair Program;" The Professional Career Development Institute; 2000

Resources

• Evan Fell Motorcycle Works: How to Clean a Motorcycle Carburetor, The Right Way
• Do The Ton Cafe Racers: Cleaning Carbs on the Rack by Boiling in Lemon Juice