How to Take the Carbs Off on a CB 900 C

by Chris Gilliland

A Honda CB900C's carburetors are key elements in providing fuel to its motor. If properly maintained, a CB900's Keihin constant velocity carburetors are reliable and work with very few problems. Issues may arise as regular maintenance slacks off. Old fuel and dirt can clog the carburetors' passages and jets, restricting the flow of fuel and preventing the motorcycle from running. Little can be done to remedy the situation without removing the carburetors entirely. Extracting the carburetors is not as difficult as it would seem, as the CB900C's frame allows almost unrestricted access after some disassembly.

Park the motorcycle on its center stand. Remove both frame covers from the CB900. Grasp the sides of the cover and pull it away from the rubber grommets on the motorcycle's frame.

Unscrew the mounting bolts on both sides of the motorcycle's seat, positioned near the rear fender's support rails, using a 12 mm wrench. Lift the rear of the seat up and pull it to the rear of the motorcycle until the tang under the nose of the seat is freed from the frame.

Turn the fuel valve, positioned on the lower-left side of the fuel tank, to the "Off" position to stop fuel flow. Remove the bolt at the base of the fuel tank with a 12 mm socket and a socket wrench. Raise the fuel tank's base off the frame and pull the fuel line off the tank's valve. Pull the fuel tank toward the rear of the motorcycle until it is freed from the rubber posts near the handlebars.

Loosen the air box mounting bolt, positioned at the front of the seat's mounting rail and at the base of the fuel tank (when mounted), using a 10 mm socket. Loosen all four clamps attaching the air box to the carburetors with a Phillips screwdriver. Push the air box away from the carburetors.

Drain the carburetors' remaining fuel supply into a small container. Place the container below each carburetor. Unscrew the drain screw on the bottom of the carburetor with a flat screwdriver to drain the fuel. Tighten the drain screw and move to the next carburetor. Repeat until all four carburetors have been drained.

Loosen all four clamps securing the carburetors to the motor, using a Phillips screwdriver. Pull the carburetors off the motor and out from the left side of the motorcycle's frame. At this point, the carburetors will only be attached to the motorcycle by the choke and throttle cables.

Loosen the small screw securing the choke cable to the front of the carburetors, using a Phillips screwdriver. Pull the choke cable away from the carburetor. Loosen the throttle cable adjusters' lock nuts with a 10 mm wrench. Turn the cable adjusters clockwise to loosen the throttle cables, then pull the cables off the carburetor.

Items you will need

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About the Author

An avid motorcyclist, Chris Gilliland has immersed himself into the two-wheeled world while balancing work life and raising three daughters. When he is not managing the parts department of a local, multi-line motorcycle dealership, Gilliland can often be found riding, writing or working on his motorcycle blog, Wingman's Garage.