Anyway, the scoot was a bit sluggish but would pickup and then start 4 stroking at about 3/4 throttle in all gears (with Mark on the back I didn't achieve that in 4th
). I've not changed anything since we got back and have just been out to the shops (8 mile run) on it and managed to get it to 4 stroke flat out in 4th at 65mph(Garmin). On leaving to come back it wouldn't fire up as normal but did run on the choke until I turned it off at which point the engine died and wouldn't fire up with or without the choke. Took the plug out which was quite black and messy so stuck a new one in and it fired up straight away. Now for the strange bit, the 4 stroking has completely gone 
I actually saw just over 65mph in 3rd on the way back 
its never done that before, 60 mph was the best I had doing some carb fine tuning on the morning I left for Ireland. Just wish the road had been clearer so I could have seen what it would do in 4th Is it likely that a plug would do this or have I developed an air leak