How to Tune-Up a Honda Metropolitan

Remove the battery cover from the footwell of your Honda Metropolitan. The well is under the rubber mat and held in place with a bolt or screw (depending on what year Metropolitan you have). Disconnect the cable from the negative post. Lift the battery out and check for any leaks or corrosion on the post. Clean if necessary with a wire brush. If any liquid is present, replace the battery. Return the battery to the compartment but do not connect it.

Remove the rear side fenders. These are bolted or screwed onto the frame. Once the fenders are removed, you can see the drivetrain on the left side of the scooter and the air filter and carburetor on the right.

Examine the drivetrain casing for cracks. If you see a crack, take your Honda Metropolitan to a dealer or scooter repair shop immediately. If there are no cracks in the casing, continue on to the next step.

Locate the gear oil drain plug. The plug will be on the under side of the drivetrain. Place a drain pan under the plug and, using a socket wrench, remove the plug and drain all the gear oil out. Replace the plug and hand-tighten when done. Locate the fill plug on the top of the casing and add in the recommended amount of gear oil as per the manual for your size Metropolitan engine.

Remove the air cover filter and air filter. Discard the old filter.

Spray carburetor cleaner inside the carburetor through the opening accessible through the air filter assembly. Look inside the carburetor, if you see excessive amounts of a black carbon deposit, take your scooter to a dealer to have the carburetor removed, dismantled and cleaned. Install a new air filter and replace the filter cover.

Remove the spark plug from the left side of the engine, there is only one in a Honda Metropolitan scooter. Spray the tip of the spark plug with carburetor cleaner and gently clean remove off the tip with a wire brush. If you have had the same spark plug in the engine for a year or 500 miles, replace it with a new one rather than clean the old. Return the plug and reconnect it.

Locate the engine oil drain plug. This is usually on the center bottom of the engine (more easily accessible from the left side). Put your drain pan underneath and remove the plug allowing the oil to drain. Replace the plug and open the fill plug on the left top side of the engine, add in the recommended amount of oil as per your manual for your size engine. Replace the plug.

Re-connect the battery cables and start your Honda Metropolitan (while in neutral and on its center stand). Adjust the carburetor with a flathead screwdriver by turning the adjustment screw on the right side of the carburetor (factory carburetor only), turn it in until the engine begins to sputter and almost shut off and back the screw out until the engine runs smoothly. Shut the engine off, replace the side covers and you are ready to go.