Kevin, that's what I've been told too, but I've never seen a 350 that could support the weight of a grown man for more than a few seconds...might well be the fact that everyone's bike here is clapped out to some degree.
Mine won't hold me past 2-3 seconds, but it's only got around 275 miles on new piston/rings/cylinder and it feels very good by local standards.
Ace, no idea if I can find a proper gauge locally. I know they exist but dunno if they're any better than the Harbor Freight cheapies found in the US.
I began to suspect this was an ignition/timing issue, so I went and replaced the contact breaker plate, with new points and condenser. The old auto-advance unit seemed much smoother than the new one I had, with nothing disconcerting going on, so I left it in place.
I tried ping timing per Snidal and settled on about 2/3 of the way advanced. I never got a clear pinging like a spraypaint can being shaken (heard that on my UCE 350 once); at best when I was on or past 3/4 throttle on the hill I heard a vague rattle underneath the engine and valve clatter. Bike also became really hard or impossible to start around that setting, so I backed off a bit and seem to have found the sweet spot.
But it didn't solve the spitting problem and idle remains lumpy despite my continued best efforts to tune it smooth.
Question, though, since the guy who put the bike together did many suspect things...if I'd been unable to make it ping when fully advanced at the contact breaker plate, what then? Can you just break/re-set the taper and start again? That was my only guess.