Hello- I tried the 'jetting forum for this problem, with no luck, so hopefully someone here can help out. My buddy has an '86 600r that seems in decent condition. It had been sitting for a while, and it supposedly ran before he got it, but not too well. It had a stock intake with a crappy, filthy K&N type filter, stock header with White Brothers "supertrapp" style exhaust with 12 discs installed and 45 pilot, 125 main 1.75 turns out on the air screw, needles @ 3rd slot. I took the carbs apart, cleaned all passages with cleaner and compressed air. Removed the jets and cleaned and inspected them and found no issues. Assembled carbs, installed a new stock air cleaner and put in fresh fuel. I could not get it to start. No spark. Traced the issue to what I thoght might be the stator, and my buddy just happened to get a free Ricky Stator with the bike, so I installed that, but still no spark. Put an Ohm meter on all electrical parts, and found the exciter not in spec. Replaced it with a new unit. Full choke, TDC, kick and it fired first try! Great! I let it run for a bit, then knocked the choke down to mid point, it still ran okay. Pushed the choke off, and it immediately started to cough and pop until it died. Did the whole procedure again, with the same results. Sounded like a lean condition. I took the carbs out, disassembled, cleaner, compressed air, etc. Installed everything back in and it fired and ran great on full and mid choke, but stumbles and dies when the choke is off. So, we got a 48 pilot, 128 mains and I once again tore the carbs apart and THOROUGHLY cleaned them. I tore everything I could off the carbs and inspected each part for issues, slides, air valve, jets, etc. I replaced a couple of O-rings on the tubes that cross between the carbs, but everything else seems okay. Fired and ran great on choke, but once again popped and died off choke. I had someone keep the bike running off choke with the throttle while I sprayed starting fluid and choke cleaner around the carb plates, expecting a vacuum leak, with no results. I am deserate at this point. I checked timing, I have checked and set all the valve lash, I even removed 6 discs from the exhaust with no change. The bike runs great on full and mid choke- no hesitation, absolutely not 1 ounce of smoke, and the sparkplug shows almost black (but I cannot do a true plug chop because of the idle condition) The 48 pilot is the largest made for the carbs that we can find, but I can't imagine this needs a bigger pilot- I feel I am missing something in my trouble shooting. Any ideas other than removing the gas cap and parking a new bike under it? Thanks!