It's a hyper 21 3 port I believe and the first plug was a bit dirty but I think that blew because I left the igniter on too long whilst figuring it out, the second plug looks clean and fine, the filament has broken that's all. I have started tuning from factory settings yes but have played around quite a bit to teach myself.
What is the best way to test for an air leak as I don't know what is easy or hard to tune as I haven't had a nitro rc before so am not sure if this is the problem. I did get it running and ran a few tanks through it doing some high speed runs and it seemed ok but then when I next looked at it later that night the plug had gone.