So have spark but still won't run?. WD40 should get a result if everything else is in order. Personally I use CRC5-56 which I guess is the equivalent of WD40. Have a video up here somewhere of my yamy 100 running on it with no carb just straight down the spout. The other night I sprayed WD40 in the log fire onto some useless cheap fire starters &--won't do that again--went whoosh in a flash so is volatile & somewhat lubricating.

Eye brows need attention periodically.. (:

Next time, if there is a next time, i'll use diesel lol.

Update: just shot some Johnson's starter fluid down the air box. Nothing. Well, that's not exactly true. It kicked differently this time. Sharper, crisper. I know that makes no sense, but it's like it had a little more snap or resistance to each kick. But still wouldn't start. No sputter even (as if trying to turn over). After a few more kicks, that crispness went away and now it's back to its regular resistance. I guess that steep hill is next.

Not pushed a crank seal out. Sorry my vintage iPad won't update so not sure what bike at the mo except 250 generally don't blow seals out. Will look later on main computer.

I've replaced the crank seal. It's new.

Seal on each side as i'm sure you know but could other have been pushed out pressure testing. I guess it'd show imediately even if it happened right at end of testing. I did have one blow out right at the end of running on a 100cc & had me stuffed for a while when i went to restart.

I replaced that side when I rebuilt the clutch a few years ago.

Just did several bump starts/push starts/clutch pops. In second, choke off: gurgle, gurgle, real low, never caught. All these are in second: choke on, cranked like a banshee, screaming high rpms. After this, it would start via kick starting, choke on or off, but always scary high revs. Now, the tach that's on it is a '71 tach. Does that matter? Is that accurate? If so, even though it sounded terribly scary high, tach always read 7,000 rpm. Adjusting the carb's idle adjust screw at various positions had no effect. I even tried giving it some throttle to see if that would "unstick" it, no effect. Smoked a little white smoke first couple of times, clean after.

So it's running now but screaming--if I'm understanding it all.
Is the throttle slide misplaced on the guide pin which would put it on about 3/4 throttle which would be scary if ya push starting it & end up hanging off it like a flag.