This is starting to drive me crazy. Maybe someone has an idea. My 1981 kz 650 csr 14000 miles always garaged has a problem. The bike is in very good condition BUT... After riding for a short period, maybe 10 minutes, a few miles, it starts missing sometimes barley able to keep it running. It sounds like it is running on 3 or even 2 cylinders. This usually starts when I slow down to make a stop and the rpm drop to an idle. It will miss badly for a time. it seems to clear up after a bit if I can manage to rev it to 6000 or so. Almost like the vibration shakes something then Instantly, full power. like someone turn a switch on. It only happens once per ride then it could be good for hours. shut it off for a while and it will happen again. NEVER HAPPENS when I am near or at home to effectively analyze it. Fuel is good. no water in there. I had the carbs off a couple of times. first time there was some dirt that would clog the main jet and fall off. thats all cleaned out. put new coils on new wires plugs. The timing advancer seems to be in proper order. I've been in the mechanic end of the auto industry(maint,repair,race) since I was old enough to hold wrenches for my dad and brothers dealership so I have a some knowledge. I may be stupid but i'm not a total idiot. Anyone ever had a problem like this?