RE: Saito 100 idle
Pinching the fuel-line at idle; if the mixture is set richer than normal, will momentarily raise the RPM...
However, if does not constitute a "pinch test"; as it applies to a two-stroke engine...
In a four-stroke, the crankcase does not participate in fuel induction and thus fuel cannot pool in it; like it can in a two-stroke...
Pinching the fuel-line does, however, lean the mixture momentarily, causing the ignition to occur sooner and the burn to reach maximum pressure sooner...
This causes the RPM to increase momentarily.
This idle RPM is pretty close to the bottom line.
My Saito .72 cannot idle any lower either.
Saito engines have a pretty hot cam, which like in full-size engines, keeps the idle elevated...
With just one cylinder, this engine cannot really have 'lope' and will simply shut-down, if you try.
A YS will idle lower, because its forced induction allows getting good power with milder cam timing, so it can easily maintain a 2,000 RPM idle, but only on a more expensive fuel...
EDIT: Closure.