Vibration on mine was worst at 5-6000 rpm, where the plane sounded like a buzzer with the shaking of the monokote. Wouldn't idle right but was a great at full throttle. My theory is that the leak was nonlinear, ie there is some threshold suction required to start the leak. On mine, I think the threshold was reached at a fairly low rpm. At higher rpm, the leak is just part of the needle setting but at low rpm, the leak would suddenly start leaning the engine, then shut off as the carb suction decreased when the intake valve closed, then start again on at same point on the next revolution. Now, there are a number of Saito 100's at my field. Mine is the only one that ever was a problem. At this point, I like it so well I'm going to buy anoter one since 91FS size planes are my favorite.

Roger Hill