Got the answer
Got the answer
Found the answer on the Rotax Owners Forum. Here it is for those who are interested.
I could be wrong here, but I don't think the older single ignition breaker point systems had the grey wire. If you have breaker points rather than the newer solid state ignition, the MGL tach can be hooked up. I believe you can hook the tach wire to the wire between the coil and the breaker points. This will pick up the firing pulse. Since the rotax fires at the top and the bottom of the stroke, you would have to program the tach so that two pulses equals one RPM. The MGL is programmable to work with just about any combination of pulses. Basically, you would be hooking it up like an older automobile tach. If you go to the MGL website, I'm pretty sure they have schematics showing how to wire the tach to a breaker point system.