I've been working on this bike on and off for several months, but I'm at the end of my expertise now. Motor has 32k and only runs on cylinders 1,2 and 4. I have tried everything I know, so here's the list. When the motor is running pulling wire 3 makes no difference, yet putting a plug in that wire and grounding it gets a great spark. I can put my hand over the other 3 carbs and kill the motor, but on 3 it sucks my hand against the carb, but has no effect on it running. Compression is 135-145 on each cylinder. Had tried 3 different sets of carbs, all have been cleaned, same result, no 3 not firing. Pull the plug and its wet. Pulled the head off, nothing obviously apparent. Reground the valves, new seals removed all the carbon on head, valves, pistons. With pistons 2 and 3 at bottom, I poured 2 inches of Marvel into the cylinders and 4 days later it was all still there. That tells me the rings are sealing. Put it back together, tried a different set of carbs which have been cleaned, no difference. Even changed the coil with no effect. I am really stumped here, I have worked on bikes most of my life and never ran into a problem yet that defies trouble shooting like this one. So tell me what an idiot I am and how I overlooked something obvious!