Joe,
in my very short time with planes I found that tuning and startup procedure is the key to starting and keeping
an inverted engine running. When starting alot of the problems I see are due to overpriming. I usually
do 3 flips with carb at full throttle and finger over exhast (on tank pressure system) then close the carb and
attach the igniter and hit it with a starter or back flip. On pumped engines, carb open 4 flips carb closed
and back flip with igniter on . Getting too much fuel into the engine drowns the plug. after 1st flight I kill
the engine with the TX (close throttle trim) and I don't need to reprime the rest of the day. When I tune engines
I make sure they are a few clicks rich, but never sloppy rich, I found that if you run them too rich they load up
easy and have a tendancy to oil foul the plugs when they are sitting.