Can't turn the choke off

Hey all, I have an 80 KZ750 LTD and my issue is that I can't turn the choke off. The bike starts fairly easily and though i'm new to bikes I can get a feel for when to turn the choke down or up. Unfortunately if I attempt to turn the choke completely off, the bike wants to die out. Mind you, this is after the bike is adequately warmed up. I'm not to good with carbs, especially small ones, so please help me out here even if it's just to give suggestions as to what to check. I also have a small oil leak that i'm not too sure where it's coming fom and a somewhat minor exhaust leak right before the muffler on the left side exhaust pipe. Not sure if any of that helps but i'd like to at least get this thing running good for once.

Could be a number of things.

I would say that you can turn the choke off, it's just that when you do, the bike dies.

How is your filtration? Is this the result of a gradual declination or was it sudden?

Has there been any other changes to the bike recently? (tune ups, sat for a winter, used questionable fuel, loaned out, taken to shop....)

How do your plugs look? (black and sooty, wet, oily)

Have you tried turning up the idle a bit?

Could be your pilots are plugged/fouled..

First off, try some gas treatment, and read your plugs. I advocate using a can of "Sea-foam" to attempt to clean out some of the crud that may be blocking some of your carb passages. See if this helps at all. Then, replace your plugs if you feel it is needed. (If you change/fix two things at once, it is harder to tell which one had been the initial problem.)

The pilot circuit on your Keihin CV34 carb assembly is dirty/partly obstructed. Clean pilot circuit including the slow jets.