I doubled checked the plug gap and it was spot on.
Both bikes start and run ok with the 7s in them but with the 8s they seem to run better noticeably so much so that I will be sticking to 8s from now and the 7s that I have I will keep in the tool kit as get me home if in the unlikely event the plug in the engine packs up.
I will be updating the fuel consumption on the Fuelly web site