Thanks for your reply, the engine is used and came with the model, I did however install it and all the ignition system etc, from that I can assume it ran ok at some point.
It ran ok last weekend, well enough to attempt a maiden, it ran better on the ground than in the air but due to the weather I did a few circuits and that was it.
During the week I removed the high speed needle and attached an extension to it so could tune it with the cowl on, I reset to 1.5-2 turns out but it wouldn't run without either a misfire type sound or very rough today, nothing else has changed.

One thing I did notice was the hobbyking nimh I'm using has quite a small gauge wire, it's a 2200 receiver pack so surely couldn't draw too much on this ignition?

Thanks