Jetting
Jets are located n the bottom side of the carbs. Loosen the hose clamps that hold the carbs to the motor, remove the sediment filter from the bottom of each carb, the gas will drain out of the carb so you may want to have the sled outside for this.
Mikuni makes a nice socket wrench to stick up in side the bowl to remove the jet but you can also use a 1/4" drive socket on a magnetic screwdriver or just use a deep well with a ratchet. Your jets should not have a washer but you might want to keep the wrench vertical as you pull it out to make sure.
Needles are located beneath the flat cover on the top of the carb. Held in place by two phillips screws. You need a metric allen wrench to loosen the keeper, it swings to the side as you loosen it, and lift the needle out with a needle nose. Use a good light and use the needle nose to pull the c-clip off and then reinsert it at the level you want. 1 is on top, 3 is in the middle. Retighten the allen head holder, it should rotate back into the origianl position as you tighten it. Put the cover back on and reinstall the carbs, airbox, etc. Don't forget to tighten the hose clamps and reattach you vent line hoses to the air box.