I run my kids stock ported Blaster wtith uni in the box,no lid,toomey pipe with 310 main.My other kids is HJR ported with same intake and exhaust,340 main.Kevin said try a 360 main.Blasters love the extra fuel for cooling.Just run it fat and you'll have to test and tune.Not that long of a process with those bikes.Just run it rich,They like to blow up from friends that I've seen.