Grounding?
 

I have a gsl-se with a t2 motor and a microtech lt-10s with x4. I just rebuilt the engine and it fired up right away. Now depending on the day/its mood it will run fine(still a base map). It only has about 45 minutes of run time (idling and a little revving). It started running on one rotor recently. It was the front one, and after dicking around for a while I switched the leading plugs and it was running on the rear. So I switched to new plugs all the way around. ran well for 2 minutes and then the rear rotor went out (checked with a timing gun). while it was still running I pulled off the plug wire and it was arcing against the chassis. Then I check my plugs and they were fine as I'm running normal afrs and the plugs are clean.

I have the batter in the rear with it grounded with guage 1 to the chassis. the block however is grounded with a 12 inch segment of thin batter wire to the chassis. Could this not be enough ground? I figured a bad ground would just result in weak spark or intermittent spark. With the timing gun the non-sparking rotor is either firing perfectly or not at all.