ok i put a 38mm keihin carb on my quadracer, it had a 140 main jet in it. the carb has no adjustments on the outside except on the choke button you can adjust the idol there, anyways it would not run right it was loading up bad so, i bought a jet pack for it and installed a 130 main in it, when its warmed up it purrs like a kitten alot of top end really nice.but the prob is its real hard to start you kick forever until it will finally start should i go up a size on the main jet? any info would greatly help, like i said when its warm wow'' vicious. love it. i went down on the sizes all the way until it ran good on a 130 jet. its only hard for the first start up then it starts right up easy after its warmed up.