Horizons Unlimited - The HUBB - XT 600 Hard to start cold engine

Greetings all:
Name here is Marty. I'm a new member of this forum, though I have browsed it for info in the past. My ride is a 94 XT600 with electric start and a little over 10,600 miles. I bought it around 2001 and it ran great. Then I let it sit maybe 12 or 13 years. Tried to get back on it about 4 years ago and naturally it took quite a bit of work to get it going. I expected to squirt some carb cleaner in the carb, add fresh gas and go. Nope. Carb was much too clogged. Upon removal of the carb both of the intake boots to the head fell apart. So 2 new boots and a carb rebuild kit from ebay and I was back in business. All was well. For a while. Then I wound up leaving it sit for another year or two and It was very hard to get running again. When trying to start it it would run for a few seconds then die. I kept restarting it and the run periods slowly got longer until it would finally keep running. Once warmed up it would start and run fine. But it was a bitch going through that starting procedure every morning. Especially since I only ride it when I go camping. No garage. No electricity for battery charging.
Well I last rode it in mid August of 2019. Less than 2 months ago. I tried to start it this morning and it wouldn't even spit. It would run on ether, but not fresh gas from the tank. So I got the toolbox out and stared at the carb. I REALLY did not feel like tackling that job. Hmmm. I wonder.... I pulled the tank off just to get it out of the way. Left the fuel line attached to the carb. Got the line to stick straight up between the frame and side plate. Luckily I have a small funnel that fits into the fuel line. I sprayed carb cleaner into the funnel until it filled. Cranked the engine for a while but it would not accept the fluid. So I left it sit for an hour or so. Finally the fluid began seeping into the carb. I cranked the engine to pull the fluid through. It was a slow process but it finally started catching. Spray. Crank. Let sit. Did this many times through the course of the afternoon. Run time got progressively longer. Eventually it got to running on the carb cleaner. Of course it was popping, spitting and smoking. Replaced the tank, which already had fresh fuel and now it purrs like the proverbial kitten.
The objective of this procedure was to get the bowl, jets, orifices, etc completely immersed in carb cleaner without removing the carb from the engine. Sometimes it takes a bit of time for the carb cleaner to dissolve the really stubborn clogs, so take your time. Let the cleaner do its' job.
After reading some blogs I think this bike seems to be more susceptible to this problem than most. Over the years I have treated many bikes the same way I treat this one and never had such a hard time putting them back in service. Is this specific carb the problem? Or is it modern fuel? I'm not sure of that answer.
Regards,
Marty Braun