Very interesting. I took a look at the older "parts" motor and sure enough, solid connectors where exhaust comes off the engine. That makes perfect sense. I'm fairly certain it's not the plugs. I've replaced them multiple times. I'll try pulling gas from a separate tank directly to fuel pump and see if there is any difference. And the nests! Yes, I've dealt with that on my 250. Was riding a few years ago and couldn't believe the smell of burning nest, urine, whatever. It ran hot that day and I'm lucky it survived. This year i didn't do a good job of checking and sure enough, a nest. Now that one is out of commission too. Good stuff.
The electronic stuff is my weakness. Lucky to have an electrical engineer that works on these with me. we replaced the green switch box, wiring harness and everything works form spark to lights. It has a CDI system which is "powered by a flywheel mounted generating coil and a trigger could attached to the housing." I'm probably wrong, but with how easy it starts and smooth it runs, seems timing isn't horribly off. Even if off a bit, wouldn't the thing still rev up more when throttle opened?