So, the throttle problem was twofold... throttle housing allowing twistgrip past the zero position under hard use, leading to the cable popping out the bottom and perversely hanging up enough inner wire to put it at like 1/3 open. Ordered new throttle. Did this to keep the cable in place till it arrives.
But the engine was still starting to lean out over the course of every ride, getting to the point of no fuel in carb at all. Coupled with my throttle issue the engine was just skyrocketing through the revs...kill switch would barely cut it off. After chasing through sticking carb needles (since applying the tickler didn't give me a gush of fuel) and tank cap vents, I found the cause.
Nice new Tygon fuel lines get even softer and droopier as engine warms up. They start to sag and kink. First I splinted them at the carb using some big 3/8" fuel line, which helped but only forestalled the inevitable.
Turns out I just had to put the old lines back on and voila, nada problemo. The whole Tygon setup was just drooping on itself and kinking up.
Of course, because I am me, I also lost the oil tank cap a ride or two ago, possibly while flogging it back to life by the side of the road on the last test. So this got me through today's test with the new fuel lines; sushi takeout to the rescue. Replacement to arrive with the new throttle on Monday.
But today's ride was spectacular. Weather, local VA scenery. Blew past the CIA HQ at around 85 but the carb got a little balky at WOT. Maybe needs that float bowl extension after all.
Certainly the brakes are performing much better with the new cable, but going fast is an exercise in nerve even with them working well. Might put a twin-leading-shoe brake plate up front if I ever plan to use it in anger.
But for today, burbling along at 45-50 most of the ride with nothing to prove and a big grin may have been one of the best rides of my life.