The re-builder said that he's fairly sure he replaced the accel pump spring; it was a kit.
Keep in mind, it was doing this before the rebuild. After the rebuild, this issue lessened in severity. I played with the timing to completely eliminate it, so as far I know, it was a combination of the carb rebuild and the timing that solved it for me in the past. But only recently, it reared it's ugly head back up.
First thing I did was go to the timing, and found that it was off. So, I set the points gap is set in the dead center of the tolerance range on 1-4 and 2-3, and my test light lead comes on EXACTLY at the right time, so I know timing is very spot on, by the book. OEM points/condenser, and those also don't have very many miles on them. I confirmed that the advancer seems very tight with a strobe...no oscillation or anything. Of course if I "mildly" wrap the throttle with the strobe, it only advances half way while it sputters until I back off and slowly bring it up. Anyhow, the advancing mech seems tight. So I'm pretty sure I ruled out everything with the timing system.
I noticed on the carbs a week ago that the air mix screws were 2-3 turns from all the way in, which is way out of spec. It's been that way for a few years, so hopefully it doesn't confuse what the plugs show. I backed those down to 1.5 turns from all the way in, but didn't impact this issue. I think those were originally set by a 40-50 year old exhaust analyzer (a "Heathkit"), and I've only recently started to question its accuracy. Also as I've mentioned, I removed all clearance between the pump rod and the "tab", which didn't have any impac (yes, you can do this while the carbs are still installed). I also tightened up the air boots (some screws were lose) which didn't have any impact either.
It's about 30F here. I let the bike warm up for several minutes (7 minutes or so). Perhaps I should let the bike warm up for much longer before trying to twist the throttle grip? When it's able to idle perfectly and smoothly without choke, I've been deeming that as "good to twist the throttle!"
Thanks for the continuing help! Nope, I don't expect it to "wrap" like a new bike, but I don't feel that I have to be "careful" with the throttle if I wanted to rev it!
I'll post pictures of the plugs tonight. I'll also run a drill bit through the mouse ears to clean them up a bit. We'll go from there!
I've noticed on previous threads that "lucky" recommends a larger pilot jet, like a #40, but my bike is bone stock (accept for the K&N filter)...so not sure. Hopefully tonight you can help me determine a list of what to order so I can slap it all back together.
One thing that I found interesting is that when I obtained the bike long ago, it had individual filter pods. The bike ran pretty darn good with them (no wrap issues), except for on windy days at high speed. Interestingly enough, the jets were all stock for the bike. So I wonder if the jets have been drilled or tampered with so that it could run good with the pods, which is causing running issues when I got the bike back to "stock" with the airbox? I remembered awhile back when I put the airbox on, I didn't touch the carb, and the bike immediately ran even better (more consistant acceleration and more low end) so not sure...
Anyhow, just shooting the breeze here.
Twotired, it sounds like you think the "squirt" should be instant, the moment the throttle lever is moved on the carbs...if that's the case, I will certainly check that as well.
