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Well, after reconnecting my wiring, I got my KZ400 running again. It still sputters and dies, so I covered the throttle valve rings with grease and it idled fine.
The problem is, it idles at 4k RPM in first. I didn't realize until I had taken a stroll around the block that I couldn't get it any lower. When I pulled into my driveway, it lurched, the rear wheel lost traction and I went down. I pushed the bike away instead of trying to save it and suffered a dangling left blinker and a bent up shifter, but more importantly, the wiring is messed up again.

I put the key in and turn it to on, and nothing shows up still and the electronics don't work.
My wrists is bothering me wright now, so I'm taking a break and allowing the JB weld to fix my blinker.

Any clues as what I might have knocked loose?

I also want to say that it won't stay running if I don't rev it. It did it for the previous owner, too. If I pull the clutch lever, the engine dies.

All right, I got it running again, but now it's having the same old problems. It refuses to idle for more than 5 seconds (Literally) and it is incredibly hard to get it moving from a stop. I'll put it at 4k RPM and it will still try to die on me, and when it does get moving, it starts sputtering like a maniac.

The carbs are clean, I've sealed the holes I had, what could the problem be now? Should I try replace the rubber manifolds?
I was thinking of buying '77 or newer carbs to see if that would help, along with a new head gasket. I just don't know if newer carbs would fit my '76.

I found a seemingly complete set of carbs for '77 and was wondering they'd fit.
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Electrically..... get a wiring diagram and a multi tester, start at the battery and test everything. While you are testing every wire and connections, have a good look at each connection for corrosion and tightness. Make sure the grounds are clean and tight..... by 'make sure', I mean take them off and clean the conducting surfaces to bare metal before re-attaching them. It sounds like one of the safety cut-out switches might be bad. But with the history of this bike, everything needs proper checking.

The carb trouble sounds very much like an air leak someplace in the intake tract. If the boots between the carbs and intakes in the head are cracked, dry or split, replace them.

"covered the throttle valve rings with grease".... what? Could you clarify this for me please? What parts did you grease?

The grease could have sealed some bushing? on the shaft? and temporarily sealed an air leak.....

That's what I greased.

I know that a couple of the rubbers are cracked, but I was told those were the manifolds and those didn't need anything, yet I managed to almost pull one off (Those screws are in bad spots).

That appears to be the bushing the throttle plate shaft rotates in. Is there alot of play in the shaft? That can cause a noticeable air leak. Grease will temporarily seal that leak, so if the bike runs fine with a glob of grease on there, then you need new bushings and possibly a shaft, depending on what's worn. No idea about how available these parts are, a used set of carbs might be easier..... I don't know.

Yes those boots are a manifold, and they can leak from cracking or from not making full and correct contact with the carbs or heads. You already know how hard it can be to fiddle around in that area from you're clamp experience, it is easy to catch a lip on the manifold or have the clamp slip and create a bad air leak. Be awfully extra careful when putting this area back together on any bike.

There's zero play in the shaft, and when I put in new o-rings, I had to coax it in (I spun it slowly until it went in). I even gave it a blow test to see if air was going through and none was. I'm not sure if greasing it helped a whole lot, but I think it may have done something.

I don't think I have the clamps tightened, either, just barely tight (The screws were stripped, after all, extremely frustrating).

After an oil change, some fiddling with some settings, playing with the cables, etc. it idles! At 2.5k RPM... Not too much more now,, I'm going to try and get the carbs balanced later in the week and I'll be riding next Monday, woo.

thats a damn good bike when you get it running

that wierd idle stuff is common for an air leak, check the boots into the air manifold especially (its where the filters go)

to see if you have a leak in the carb boots start it up and spray some carb and choke cleaner all around the boots, if the throttle increases, it means the boots have a leak, if not, they should be solid.

good luck
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Dodge Cars

dont for get to check the valves its easy to do and good to check it. Make sure you have no air leaks anywhere except for overflow hoses dont block them off. Make sure you have the air filter on too.