If WG can make your carbs work on remote control from Texas to Alaska, and with the rebuild kits available, he is a true wizzard.
I have a reason to believe that the rebuild kits won't work in your 76 model carbs. I have tried these kits out in both the 74, 75 and 76 model carbs, and they don't work good in any of them. I have aslo gotten the same report from a few other owners. And the reson? First of all, the jet sizes in the kits are for the early 1974 model carbs, which were a bit different when it comes to the internals than the late 74, the 75 and 76 model carbs. The carbs for the 74-76 KZ400 went trough several minor modifications at the factory btw, and these modifications are not listed in any of the workshop manuals.
The second reason is that the parts in these rebuild kits are duplicated from parts coming from a worn, and maybe worn out, set of 1974 carbs (this has been confirmed by Keyster btw).
The biggest problem with these kits are the needle jet and jet needle. They will cause an extreme rich mixture in the mid range, between 3000 and 5500 rpm, with fouling spark plugs as a result. And if you try to cruise in that rpm range, the engine will run very rough. The idle was fine, so the pilot screws worked, and they performed pretty good above 6000 rpm, but as said, in the most used range, they didn't work well at all. They even run very rich in the mid range when I took out the air filter.
Also the gaskets for the float bowls was of a bad quality in the kits I bought, causing a leak from the float bowls when the bike was parked on the sidestand.
And the option? Well, the parts that will wear out is the jet needles and the needle jets, and unfortunately these parts are no longer available.
As I see it, you have got a couple of choises. First of all, clean the set you have and try it out. If they are badly worn, try to find a decent used set on Ebay. Just keep in mind that the 32mm carbs for the 1978 and on 400's will not fit the 1976 model. There was a change in the cylinder head design in 1978, and the spacing between the carbs was shortened.
Another option is to contact this company and ask if they can set up a set with Mikuni VM carbs for the 400, or at least give you some advise about the Mikuni VM's:
MIKUNI CARBS
They do have a set for the Honda CB350/450 twins, and I think the KZ400 should be able to use approx the same set up. There will be a few mods regarding the trottle cables to make though, but it should work.
Anyways, whatever you choose to do, I hope you can get your bike fixed and rideable.
Post edited by: ibsen22000, at: 2006/05/29 09:20