I have a 2003 Mule 3010 4x4 with a Mikuni carb on it. The brass plugs have been drilled out and I am in need of new jets to replace the oem pilot air jets. I ran across a discussion on another forum that talked about enlarging the jet openings to .020 and replacing the oem jets with industrial (?) servicable jets. Does anyone know where I could get replacements and/or any knowledge of this process. There isn't a whole lot of information on the subject.

 

You can probably buy the pilot jets in about any size from a dealer/shop or on line from a place like Jets-R-Us? No drilling, drilling may screw the inner surface up enough to actually reduce flow due to turbulence of the flow. A friend had that happen, drilled the jets bigger, ran leaner. Find out what's in the carb and even go to a dealer to see if they have a size or two bigger... or smaller depending on your elevation where you run. There are I think two designs of pilot jet threads used in Mikunis that I know of. So you need to know what style it is.

The way to know what you need for pilot jet is easy to learn. If the idle mix screw is on the intake side as opposed to the air box side you are adjusting fuel flow with the idle mix screw. If at the air box end it is adjusting air flow. I'm betting it is the fuel mix. Screw in to make lean, out to make rich. There will be a range where the idle will rise and hold for a turn or so. Run mix screw in gently. Turn out 2 turns. With engine running and idling, turn screw in until idle drops (leaning out) counting the amount of turns. If it drops immediately it is leaning out, start turning out. Turn out until idle drops again (too rich), counting turns. If it doesn't drop the pilot is too lean, go one or two sizes bigger. If it is within 3 turns adjustment will be half way between the lean idle drop and the rich idle drop. If the adjustment is less than 1 turn out go one size richer on the pilot, if more than 3 turns out go one size leaner on the pilot.

Maybe that helps a bit.