Inliners International Forums General Discussion Hi Performance 261 with 4:88 gears

Those cranks are steel and relatively strong, but they are old. Once you get into the upper rpms, over 5000, the harmonics are bad. But the other issue with higher rpms, the head simply will not breathe that high, at least not without doing some crazy stuff to the head, and even then, probably not all that much of an improvement.