KZ 440 stalls when clutch disengaged

Hi everyone. First, thanks for the add. I bought a ‘77 440 a couple years back and am now just getting to work on it after life has slowed down a bit. The owner before me had started a cafe build and I like it just fine. He was having a hard time sorting out the jetting and had had enough so sold it for a lot less than what it should’ve been. I’ve got it running really nice at idle, but when I release the clutch lever in 1st it bogs and stalls. I don’t know if these had a side stand safety switch or if it’s a clutch switch, but it sure seems that way. He did some rewiring and I can find an online manual for earlier than 1979 (maybe 1980?). Hoping someone might have some insight on this. If it is a clutch switch, where is it located? I’m thinking part of the wiring bundle that comes from the left side engine/trans cover?

Is this a KZ400 or 440? Or a 400 w 440 engine? or ....??? .1980 was the first year for the KZ440 in the USA.
The KZ400.com site has information & wiring diagrams for the 400/440s. Do not use the forums as they may harm your computer.
Your bike may not have a clutch switch >> normally located at the clutch lever perch & it would only affect starting the motorcycle.
I'm not aware of any other starter interlock switches on an early KZ. Some 81 or 82-on models had a side stand switch.

I would do a basic clutch adjustment. On some models, including the later 400s & most if not all 440s, you're supposed to turn the clutch release adjusting screw counterclockwise first until hard to turn, then clockwise 1/4 turn. Some manuals are ambiguous as to the direction.
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I’m not really certain now. It must be a 400. The clutch and brake levers are aftermarket , but the signal switch appears original. It only has a kick start and there is nothing electrical attached to the clutch lever. It feels hard to roll compared to all the other bikes I own (‘92 cbr, ‘83 shadow, ‘83 virago) Is that normal?

I’ll try adjusting the clutch. Thanks so much.

The bike should roll easy. maybe try putting it in neutral to see if it rolls easier.
The owner's manual or service manual should have the clutch adjustment procedure. Slacken the cable beforehand by turning in the thumb wheel adjuster at the lever & the mid-cable barrel adjuster (if your clutch cable has it). After doing the clutch release adjustment, adjust the cable to take up the slack. There should be a few mms of play in the clutch lever. Also, I would lubricate the cable, especially the cable end at the clutch lever. I use Permatex ultra disk brake caliper grease in the little packets on the cable ends. 1 packet should last for years.

I had similar issues with my 78 kz400 that had been sitting for a couple of years before I got to it.

As recommended adjusting the clutch cable should come first but if you still are seeing the same symptoms then the clutch may be sticking.

If that is the case then you can try to break it loose a couple of ways. First you can try putting it in a higher gear, try 3rd, and rock the bike back and forth. You may hear a pop from the clutch area. This worked for me once but did not for another bike. Another thing you can try is to start it up, put it in gear, rev it as high as you need to while feathering the clutch to get the bike rolling and pick up speed. Eventually you should be able to let the clutch out all the way and you should feel the clutch release.

Maybe the brakes are dragging. A kz400 should roll very easily in neutral.