R3 classic running like a twin. Backfiring and stumbling

[busy_rydin]

I haven't posted since 2020 but I'm back! Here's the situation. My 2006 RIII Classic is backfiring and missing like a MOFO. I just returned from a bucket list ride down to Key West on Father's day weekend and just about when I hit the Overseas HWY my bike started to snap crackle and pop. Felt like it was misfiring and stumbling. Of course... there is nowhere to stop out there so I had to push through. I made it to the bottom and back up to Port St Lucie before I had to put it on a trailer. It never went out on me I just didn't want to push my luck any farther... (had already done 383mi on it sounding like that).

Got it back home and started investigating. Here are the things I checked:

• The front cylinder header feels cool to the touch at first start while the rear 2 heat up fairly normally
• Checked the vacuum hoses to make sure there were no MAP sensor issues causing stumbling.
• MAP voltage is within spec and no found cracked lines
• Checked the clips on the ignition coils and even swapped the #1 and #2 coil to rule out coil failure. No change, the #1 cylinder still cool to the touch.
• Checked Coil impedence and verified spark at the plugs. There is spark but I changed all of the spark plugs anyway to rule that out.
• Ran TUNE ECU to verify TPS voltage and reset. Everything is within tolerances with the exception of the MAP voltage which appears to be due to the cylinder not firing so it's reading incorrect air values.
• Did a compression test and all cylinders are at 190 PSI (WHEW, I thought I really messed something up)
• Checked for correct resistance at the fuel injectors. All clear there.I figure if I have compression, air, fuel and spark.... why is it not firing?!?
  Any suggestions on what I can do to further test the fueling? That seems to be the area least explored with the exception of making sure the injectors have not failed. Any cleaners recommended to make sure injecter ports are not clogged? Any suggestions are much appreciated. I'm missing my ride up to PA this weekend because of this.

 

[busy_rydin]

I actually went to my local dealership this morning to feel them out and he (maybe jokingly??) said, "based on what you're telling me, it doesnt sound good and I wouldnt waste the money on it. Just buy a new one. Those bikes always have problems". Mind you, this is the first time I've had a problem with it and I have no plans to get rid of it. Only 18000 mi and I got it at 6000. There's life in this ol' girl.

I wont be taking it to them to troubleshoot. So I'm here. Getting more intimate under the big girls skirt