Hi, I've had a '96 Heritage for about 10 years. It's an 80 inch with an EV-27 cam,modified Keihin carb, .050 off the heads, 2 into 2 aftermarket pipes. Dyna S Dual Fire Ignition. Compression tests out good. For a long time now is, that the Rear cylinder sounds like it's missing at idle. The front cyl sound is very pronounced. But, the back cyl. sounds like it hits about every 5th stroke. More noticeable when motor is hot. The rear cyl does'nt warm up as fast as the front either. Now...when I half-choke it when hot, the rear Jug hits Every beat. I've been chasing a possible vacuum leak for years with this issue. Over the years I've changed all intake seals bout 3 times. Intake manifold at least twice. I've changed plugs,wires, you name it. Also running a #60 pilot jet. Plugs burning good. The motor is not running on 1 cylinder. It's just weak in the back. Mid range a & hi-speed is great! I just tried this...Closed spark plug gaps down to .025. from .038. Low & behold, The rear fires every time now! I've also had about 3 coils on this ,too. It's now running Great with the Smaller spark gaps. Would my slightly higher compression be blowing out the rear cyl spark? I'm stumped! Any help would be appreciated! Thanks!