Thanks all, there is a small hole in the exhaust which I have patched up and I intend on taking off the carbs and giving them a good clean out / service. I'll check all the rubbers and see if anything has perished and needs replacing too.
Just a quick note to Cynic, this is a four stroke V Twin not a two stroke :-) it's basically the same as the XV535 Virago just with smaller 400cc heads.