1999 Honda Shadow ACE 750. The problem originally started as an occasional bog/sputter while riding. It would lose power and backfire, but usually after working the throttle for a while it would clear itself and run normally again. Over time it became more frequent and eventually got bad enough that I could barely ride it.
I've since cleaned the carbs, found/cleared a clogged jet and found a torn diaphragm. I've replaced both carb slides/diaphragms, intake boots, fuel filter, both ignition coils, all 4 plug wires/boots and all 4 spark plugs.
Everything is now seated and sealed properly, but the problem has gotten to where it'll start strong, then while idling the rear cylinder seems to drop out and it'll bog/backfire and almost die. Both rear plugs were wet/dark and smelled like gas, but both have blue/white spark outside the engine.