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Carb Cleaning 101


The Carb is a fairly simple device, but being small can be a real challenge to clean all the small passages and jets in it.

If the inside looks anything like this I have found that bead blasting works well.
 Another option is to use Hoppe's #9 gun solvent. Give it a good washing with soap and water after soaking for a day or two in the solvent.

If it looks to be just old varnished gas you can soak it in a carburetor cleaner such as Yamaha carb cleaner found at most motorcycle shops. The instructions on the bottle say to dilute the solution, but I use it full strength with no problems. It does not harm rubber or plastic. If you use brake cleaner or carb cleaner be sure to remove the Hi alt knob before spraying, they both WILL eat the plastic knob.

 Remove the petcock and fuel filter.

Once opened up remove the float pin. If it’s stuck, using a small punch or nail VERY gently tap it out. Make sure you support the opposing post. If you break the post off you have just trashed the carb.


Remove the Main, Idle and float valve.


Next, remove the emulsion tube. (the emulsion tube on the round bowl and Ko carbs come out with the main jet holder)

With the main jet out, use a wood dowel (a golf Tee works great) drive out the tube.

The emulsion tube has as series of holes in the sides as well as the center hole that the main metering rod go in.

 The slow idle jet also has holes in the sides. Now the hard part, holding the jet up to a good light you should be able to see two VERY small holes going through it. To clean it I use a strand of wire from a soft wire wheel. Be careful not to bore out the holes. It will cause you problems if you get the holes too big.


The upper left hole goes to the Hi alt control. The one on the lower left goes to the slow idle jet and adjusting screw as well as the small hole in the top of the carb by the main metering jet, as can be seen in the emulsion tube removal photo. The port on the right goes to the emulsion tube/main jet.

 Now that all is super clean reassemble the carb. Be sure to put a new O ring on the emulsion tube. A touch of oil on it makes it slid back in place easy. The tube is fully seated with the main jet.

 Set the float height to proper setting. This setting is measured from the lip of the carb body, not the gasket seat.

 The setting for a Four screw square carb (used on early K1s) 1s

.92 in/23.5mm

The setting on the two screw square bowl carb is .78in/20mm. It's 21.5mm for the K0 carb.

The Round bowl carb used on the 1978 through all CT 110s have a plastic float that is non adjustable

Now it’s time to put it all back together and see if it works properly. Most of the time, a rebuild kit is not needed if the rubber parts are in good shape.

 Don’t be surprised if you need to re clean the thing several times before you get all the small pieces of crud out of all passages and jets.


The K0 carb uses the same aragment as the round bowl carbs.
There is no need to remove that shiney brass tube. 

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