garynortheast wrote:Get the carbs off and apart. Clean them out thoroughly, blow the jets through with an airline. Replace every single o ring on them you can find.

is there any where i can get a specific kit to do an overhaul, if so how much?

I believe Jay (gsxr400racer) can do you a complete O ring kit if you pm him. He'll be able to give you a price on them. Also try reading this http://tonysleep.co.uk/gsxr400carbs
Tony forgets to mention the o ring for the main jet block apparently so change that as well. There are a couple of PDFs on carbs in that list further back in this thread. I haven't looked at them yet but it may be worth a read.