I have a thundertigre 1.20 two stroke engine. Never had any trouble with it, but I recently put it in a new plane (inverted now....) and I dont know if it is when I inverted it or when I put in a new plug that it started to be very difficult to start. I never noticed what plug was in it or which one I replaced it with.

But, once it is running, runs perfect. Good idle, good transition etc....

It seems like I have to prime it by holding my finger over the muffler exhaust for a second or two....because I dont get a spark...but if I hold it there a little too much, it wants to vapor lock. I completely replaced the remote glow starter, and I am getting a green light on multiple glow drivers....

Any idea's, and what plug should I run in it? I have been flying rc for 20yrs, never too late to learn something new.

Thanks in advance,
Patrick