If you are “lucky”, some of the smaller motors have a simple mount consisting of a couple of bolt studs, gasket & O ring, and nuts securing the carb to the mount and mount to motor. If that’s what you have, assuming you’ve removed the air cleaner connection, simply remove the nuts on whichever end of the mount you wish, and remove the parts carefully.
Removing carbs from a motorcycle must be done carefully to avoid damage to the carbs or their mounts. Most carbs attach to the motor with some form of flexible mount which tends to harden over time. It’s a sort of rubber-like material. The choke end of the carbs usually attach to another flexible tube which in turn connects to the air cleaner.
- If you aren’t very familiar with the bike, now is a good time to consult a manual & label each cable, and then take pictures of the setup with the labels. Check your pictures to make sure you have captured the subject well. I make notes about my pictures on a clip board as I proceed. This sort of detail can be a life saver when you get to reinstall.
- Remove the tank – get it out of the way to avoid damaging it. This will give you much better access to the carbs.
- Note, it’s usually best to leave choke and throttle cables connected to the carbs if you can, until you have the carbs removed from the motor. Also, if the choke is cable actuated, pull the choke ON which will pull the actuator at the carbs into a position that is less likely to snag things as you remove the carbs. Online groups may have some tips/tricks to help you also.
- Loosen fasteners holding carbs to their mount at the motor, but do NOT loosen any fasteners holding the mounts to the motor. If possible, loosen the air cleaner box and move it back as far as possible. On some smaller Honda SOHC fours, the CB400F for example, you can dismantle the connection to the carbs, so do check manuals and/or online groups covering your model. And at very least, loosen clamps holding air cleaner connections to carbs, at the carb end.
- Note that the carb-to-motor mounts are usually some sort of rubber-like material that tends to harden with age. If you just wrestle the carbs off these sort of mounts, you almost certainly will damage the mounts. Use hot water in a kettle, slowly dribbled over each mount. For multi-cylinder motors, go back and forth a few times, before trying to pull the carbs back (see next).
- For multi-cylinder bikes whose carbs have a steady plate just behind the mounts, this presents an leverage point. Use a scrap of wood about 1″ X 2″ and 18″ long. Hold the stick vertically on one side of the motor, with the bottom end on the motor cases behind the cylinders. Place the upper end of the stick so it contacts the front side of the carbs’ mounting plate, and with the bottom end of the stick well seated on the motor, gently pry backwards to pull the carbs free of their mounts. Do one side and then the other and your carbs should come free.
- For smaller bikes like twins, if there’s no front steady plate for the carbs, you will have to very carefully pull or gently pry them back. Never use a metal pry bar! Carbs are not aluminum as many people suggest – they are zinc alloy (aka Pot Metal) which is not strong and cannot be welded, even with TIG. Also using a wood pry bar will be much less likely to break fins on the motor.
- Once the carbs are free, on Honda fours, it’s usually best to pull them gently to the left side of the motor. Be very careful that cables don’t hang up, that the carbs don’t snag wiring, etc. Once the carbs are clear of the bike, then remove the cabling.
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