Motorcycle Repair: Carburetor adjustment, 1983 honda nighthawk, salvage yard

Question
I have a 1983 Honda Nighthawk 750SC.  The problem began when a slide in No. 4 Cylinder stuck.  I found a slide at a salvage yard and replaced it. I disasemble the all the carbs. and cleaned.  I replaced the air cutoffs on the side of the carb A(with new).  I replaced the float needles on all the carbs(with new).  The floats are plastic and appear to be permanently set (no bending).  I adjusted the set screws to 1.5 turns.  I was able to remove the secondary jet and clean, but not the main jets as they have been in too long and none would come out without permanent damage.  The slides are free moving and if I shoot air into the inlet chamber (above the choke venturi) they open and close well.  The boots are ok and I think I have them all tight, although getting the rear ones right seemed more difficult than the front ones.  The only other observation that I made was that the set screws were all set differently when I took it apart, and some were more than 1.5 turns out.  That being said, here is the problem.  I choke the bike to start it.  I warm the bike up, but opeing the choke kills the engine.  I have mercuy tubes and I did synchonize the carbs. but it was with the choke on and the engine running at a fast idle.  The engine will not accept throttle without dying unless you quickly open it completely up and then it races to 8000 rpm.  I put new plugs in and checked them after warm up.  They show some black from running rich but I think you would expect this since the engine only ran with the choke on.  I am wondering if when the choke is on, then all the vacuum is forced to the vacuum slides and the engine is idling with the slide and the needle jet open insteand of taking gas from the set ciruit.  The engine starts easily, and sounds good running at fast idle as long as you don't give it throttle or don't remove the choke.  I am frustrated.  The eninge in this bike was overhauled just a few years back, and it hasn't been ridden much. It really ran well til this.  Due to its age, I reaal don't want to sink a bunch of money into it and it seems to me that something fairly simple is the problem, I just don't have the skills to deal with it.  Got any ideas? Thanks. Roy

Answer
Hi Roy,

With the engine start and idle without choke?

Air-fuel screws may have different settings. See my files for explanation.

Send me an email. I'll return several files on carburetors that will assist you with tuning.

My email address is: mshively1@woh.rr.com

Respectfully,
Mark Shively