Full rebuild after low-side; troubleshooting idle/running problems.

[Al Capwn]

You are referring to the PAIR system, correct? My '06 had that as well, and I plan on blocking it off - the less junk to take off the easier it is. I will certainly take pictures of the before and after valves and see what we will find. Thanks for all the help, I appreciate it!

[Al Capwn]

Ok, good news and bad news.

Good news is that I replaced the head successfully and it is firing on both cylinders.

Bad news is I am pretty much right back where I started in terms of behavior. So, fuel delivery. Bike will run on ON, drive it around for a moment, and it will stall out. Put it on PRIME and it roars back to life. Plugs are showing a rich condition, but each time I give the bike throttle, it will hang up at 3-4k RPM before very slowly returning to idle.

I looked at the spark plugs, both of them have black carbon build up; rich condition. So...how can I have a lean condition symptom such as an vacuum leak (hanging revs) but carbon build up on the plugs? I can also adjust the idle screw back down and it won't start/idle, but giving it gas will cause it to start work properly and the throttle response to be correct. So, maybe idle jets clogged up somehow and the idle screw is not set properly?

Choke continues to be wonky, turning it on when the bike is warmed up doesn't cause it to increase in revs as expected. Perhaps these is an issue with the choke cable? 

The carbs are not sync'd perfectly, but I can't imagine it causing a fuel starvation issue.

[W201028]

It could be a combination of idle speed screw and idle mixture screws. I recently had a similar problem with my old ford truck. it wouldnt run at low rpm. I had the mixture screws at factory settings, and I had to bring them both out to about 3 turns so it would run on the pilot circuit. Before I figured it out, I had to have the throttle open far enough to make it run on the main jets.
Not sure if this is your problem, but check the mixture screws. Seat them lightly and then bring them out to 1.5 or 2 turns. If you havnt messed with them yet, chances are the passages are clogged, as you really cant fully clean the pilot circuit without removing these screws.