Originally Posted by
mudnut
My rb30 had the same stuff happening when I bought it. I put it on a Dyno and was getting a whopping 30kw at the wheels. :( The Mechanic fiddled with the second stage butterfly. He found it was stuck shut. The engine immediately gave us 70kw. :) He advised me to take the carby off and have a go at the second stage with wet'n'dry. I found that the butterfly had worn a groove in the bore. I smoothed the butterfly and the bore. It took me quite a few goes to get it right, but persistence paid off. It has had no such problems, for over 12months.