Thanks for the welcome and response :-) Tried fuel additives to stop carb icing, non worked really :-( I did know about the heating system for the carbs and wondering if the small pipes from the coolant system were blocked, I now know they are not as I've got the carbs off the bike, so no problems there, in response to ChristoT, I agree that smooth throttle works wonders but when you need to drop a cog and overtake a car or 3, the last thing you expect is for the bike to not go anywhere, not speed up, nothing, just judder and sound worse than Worzel Gummages tractor, not good really, so def a fault somewhere. Also had the bike almost 4 years and it's not restricted :-D Darssi, got the standard air filter in, it's clean too, as for plug caps, that is one for me to check y82ugp, was suggested I find somewhere really dark, easy here, and see if I have any arcing over, once the carbs are back on, that is one to try. I did chop off 1cm of the leads to the caps, it is a 13 year old bike and on original caps etc, made no difference but was worth a go. Arfa, I do have a multi meter, the coils are one thing I will need to look at. The local bike shop suggested fuel pump, any thoughts on this?