I have both peripheral port and pridge ported motors. I have never

recorded the opening and closing events of these engines, but my guess is
that the bridge ported engine has a bit more opening period than the
peripheral port. The peripheral port will idle down to 1200 RPM before it
starts bucking and poping. The bridge port starts acting up at about 1500
RPM. I set the idle for both at 2000 RPM.
 Lynn E Hanover

Mike Wills wrote:

Lynn,

  What size tubing did you use for intake runners on this PP engine? I've
heard numbers anywhere from 1.5" - 2.25" diameter. The Powersport guys I
think are using 1.5". My guess is that idle quality improves with the
smaller tubing by keeping the velocity up. Trade off would be less peak
power at the higher RPMs. I suspect that for our purposes and the RPM
ranges we operate at that the smaller runners would be a better choice.
Opinions??

  How does the power output compare between your PP and bridge ported engines?

Mike Wills

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