1981 KZ440 LTD carb and 2 into 1 headers problems. HELP!!!

So I bought a 1981 KZ440 LTD really cheap. The bike was dumping gas from the overflow tubes and the guy claimed just cleaning the carbs would restore it to running condition. And I thought yeah right I have heard that a million times. So I went ahead and ordered a cheap repair kit from amazon. I replaced the float valve and the other parts in the kit. So now the bike runs with out dumping gas from the overflow like it originally did. But the idle is all over the place. The guy said the jets where replaced with different jets when he installed the 2 into 1 headers. My question is. What is the correct size jets to use with the 2 into 1 headers? Or could something else be causing this. Keep in mind I have checked boots and any possible vacuum leaks.

Update: I pulled the carbs back off and started going thru them again. And I found that one of the diaphragms is ripped. I will find a new one asap and let everyone know if that fixed it.

I am not very carb savvy (yet), but what I have read is that stock jetting should be good enough to run and ride with an aftermarket exhaust if you have the stock air box. If you have them I would start there. Hopefully someone else will pop in and give a better response.

By devaughn: ... Update: I pulled the carbs back off and started going thru them again. And I found that one of the diaphragms is ripped. I will find a new one asap and let everyone know if that fixed it.

JBM Industries has the diaphragm rubbers.

Exhaust system & Jets. Are the mufflers a stock Kawasaki system?
The 440B came stock with a 2-into-1, so you could compare the jetting. Kawasaki.com, Cmsnl.com, or Partzilla which is the easiest to use.

Martin I dont belive they are stock headers and muffler. They look odd and wrong for the bike. The muffler does have baffles. And I found the JBM replacement but I like to buy from local shops before I go online. But if I have to order a diaphragm thats who I'm going with.

The oem 400/440 2-1 muffler systems I saw on EB have either Kawasaki or KHI KZ440B stamped into the muffler near the mount.