Highly developed engines use fuel more efficiently, but not if they're poorly tuned. Mikuni pilot jets are one piece of your tuning puzzle. Pilot jets are replaceable and the pilot air screw is adjustable. If the jet is too large or the air screw is in too far, then the air/fuel mixture may be too rich. That's one reason why Mikuni pilot jets come in different sizes. The brass pilot jets will deliver a precise amount of fuel so you can have your machine running perfectly. Don't waste time trying to do the impossible--replace your pilot jets and start having fun.