Wiring diagram...what KZ is this?

Help me identify what KZ750-4 I have so I can use the right wiring diagram. The title says it's a 1983 KZ750 (no letters) and the vin matches the frame sticker. It still has the original frame sticker on the neck, which says it was built in September 1981 and states that it is a KZ750H. However, there is an original sticker also still on top of the rear fender, and it says the bike is a KZ750F.

The bike is bone stock (right now) and has never had major parts replaced.

So, '83 or '81 (maybe '82) and H or F, the wiring diagrams are slightly different. Does anyone know what bike this actually is?

Try here:
www.motoverse.com/tools/vin/kawasaki.asp

And here:
www.zedder.com

Well, your frame VIN will ID the bike. However, deciphering the VIN will differ depending upon where you are in the planet, as codes differed depending on geopolitical considerations. You don't have a location in your signature so all we can do is guess. If you are in North America, then the seventh letter in the frame VIN will be the letter designation for your model...e.g. H or R or E or L (if you are in Europe, in which case the sixth letter will be the model number). Ignore the sticker on the fender...and your title, as the title will reflect what info is given to the local DMV. Are you sure the motor hasn't been swapped? BTW, your build date likely makes your bike a 1982 year model.

I'm in California. Yes, I figured it was an '82. The seventh number in the vin is H. However, there were several H's such as H1 H2 H3 and so on. How can I tell which is which? I can't see any evidence that the engine has been changed. I do have the engine number. How can that help me identify the bike? Is there a site where I can look up the engine number? Thanks!

The site that we generally look up frame/motor VIN's was given by Mike (MFolks as www.zedder.com )...unfortunately, that site is really weak on info on 650's and some 750's, including yours. Yours is an H3, BTW. The '3' merely references the year of the model, e.g. that is the 3rd year that the H model was produced. The motor VIN will tell you that it is a 750 but in the early 750(4)'s, Kawasaki used the same motor series in a number of models (different cams, etc. in different models, but all from the same engine VIN series). Models were only clearly differentiated by frame VIN.