take the bowl off and remove the idle(low speed) jet. Then blow carb cleaner directly into the hole where the idle jet came from you should see it coome out of a few tiny ports in the engine side of the carb. Immediately after blowing carb cleaner through take an air compressor and blow directly into the same low speed jet hole. You should repeat this a few times each time looking at the flow coming through the ports. Then take your low speed jet and look real close at the openings they should be round and perfectly clear. Take some carb clean and blow through each of the holes in the jet then use the compressor and blow it off (hold onto that thing tight so you don't blow it across your garage... been there done that!!). Most of the time idle problems lie in this jet. Next remove the idle mixture screw and blow through it with carb cleaner and air. When re-assembling it turn it in all the way and then out 1 1/2 turns (don't tighten it too hard!! or it will damage the screw and the seat).The next thing you need to do is remove the float by pulling the pin that slides into the carb body. Be careful when removing this there is a tiny spring clip that holds the needle to the float arm don't lose it. Clean the mating surfaces of the needle and the needle seat. next check your needle to make sure the spring inside it moves freely. If it does not spray it with carb cleaner and work it in and out with your fingers this will usually clean it out and allow it to flex again. Then reinstall the parts and check your float level. Stock setup on most mikuni carbs is the float tab set parallel with the bowl flange. So when you hold the carb upside down your float tab (the brass lever the floats use to close the needle) should be perfectly parallel with the flat surface that the float bowl mates to. if it is not parallel then take a small screw driver and adjust it by bending the brass tab until the float arm is parallel. Now remove the main jet and spray it with carb cleaner, again viewing the hole to make sure it is perfectly clean and round. In the worst cases I use a piece of fine brass or copper wire to run through the holes to clear them out, or just the bristle of your brush. Now finally before you put the bowl back on take your brush and clean out all the gunk that is dried in there. If it is heavily varnished spray it down it carb cleaner and allow it to dry and it will rub right off like a powder. The most important thing is an eye for detail blow through all the small holes that you see and look for the carb cleaner to flow through freely. Not only will it clean your carb it will also give you a good understanding of how this seemingly complex peice of equipment is very basic and easy to understand.
Last edited by Manaen; 09-20-2010 at 02:59 PM.