Thanks Auke,
Sorry for the poor description, re read it my self and it only just makes sense
Its a 1991 XTZ660 Tenere, the airbox has been removed and most of the bodywork also.
I've recently had new camchain and guides fitted, but while the guy did a good job on the engine he didn't look at the carbs.
I had the carbs off today and gave them a bit of a clean out and its getting a bit better, i will try it under load on the way home from work tonight. I think the problem was a bit of cack got in there when i ran out of petrol (forgot to take it off reserve)
Again, sorry for being so vauge.
Thanks for the help
Paul