i took out 2 shims off the head and installed a nova rossi/rb carb on my 3 port race and it is ballistic. temps went up a bit, finally, i couldn't get it over 220 before it lean bogged, run times are still crazy, about 10 minutes with 125cc in a truggy! very impressed with this motor so far, keeps up with anything out there. i want to try a 5 port next but have heard of longevity issues, crank and conrod, has this been resolved?