O.K I 'm going to put a stick in the bees nest and say this. Why not set up your throttle linkage so that when you hit the throttle cut button on your transmitter it kills the engine? Then set up your fail safe so that the throttle goes to idle if there is a signal loss. Add a quality switch to turn on the battery power and your done. No mixing, stirring, shaking, or anything else. KISS. Think about it.... how many big glow engines have kill switchs? None. I have the RCexel kill switchs on my gassers and when a brand new one went bad, Idid just this. Also leave the spring on the throttle connected and if your linkage breaks then again it goes to idle. Here come the bee's