Engine Misfire

[Bignose13]

Got an Align gov on my heli and all works fine untill this morning, I turned the gov on flew but the engine was misfiring now and then, I have checked the magnets and all was fine but I have put a new header tank since flying last, so would this cause the misfire.

[mewsikman]

Might be running a tad lean..... Change the plug it might have burnt up the last time you flew