Thoughts on Mikuni carburetors.

[Ariel Red Hunter]

I do not want to oversell the idea of changing a Hawk to a Mikuni carb. The Keihan is a very good carb in it's own right. The problem with Keihans has always been the difficulty of getting jets, needles, and slides. And the advantage of the Mikuni carb is how easy it is to get almost anything you need for the little darlings. A 26VM Mikuni has a 26mm choke(venturi), and 30mm opening where it bolts on to the cylinder head. You should not have to change the needle, but be forewarned that the needle jet is a wear item. This is not hard to visualise when you realize this engine is inhaling up to 2000 times a minute. When the engine inhales, the needle is dragging on one side (engine side) of the needle jet. Eventually, this wears the needle jet, and it will over fuel in the midrange. The needle it self almost never wears. If you ride a lot, maybe you should think about changing to a new needle jet after a year or two. Once you have settled on the main jet, the needle normally has the clip in the middle slot. Raising the needle richens the midrange, dropping the needle leans it. The pilot jet controls from idle to 1/4 throttle. If you ride much off road, especially in the eastern United States, you will want the engine to idle as slow as possible and still run. Coming down a steep trail with the engine idling too fast is not fun. If neccessary, switch the engine off with the shut-off on the right handlebar, and come down in second gear. Personally, I always set my carburetor so that the engine will not run, or even think about running, when I release the twist-grip. But most of you will want the engine to idle because you are used to cars that always idle. We are all comfortable with what we are used to. Now when you have jetted the carburetor correctly, the first movement of the twist grip will be applied as you roll out near the bottom of the hill, and the engine will fire immediatly. This is why you want to have the right pilot jet in there.