Jumped out of 3rd gear at highway speed

[aigram]

Today while getting onto a highway my '89 fell out of 3rd gear while under power, and the motor revved to the moon. The bike proceeded to roll "in gear" (allegedly) with the clutch out. This is the third time this season that the gearbox has popped out of gear while accelerating with some purpose. I returned to neutral and put the bike back in gear at a lower speed and had all forward gears afterwards.
Any idea what happened here? I'm not thrilled about having likely redlined the motor (is there a rev limiter?) and I've been wondering if/when I would run into the FJ shiftfork design flaw.

[T Legg]

One of my 84 FJ1100's used to pop out of second and third gear under hard acceleration but it always jumped out then would go  right back into gear by itself as fast as it popped out. I fixed that by installing a transmission with undercut 2nd and 3rd gears and new shift forks. I have had my bike pop into neutral from a weak shift and remain in neutral but if it was already in gear when it popped out it would alway drop back into gear. Your problem is a little different in that way.

[RPM - Robert]

There is a rev limiter. You can still mechanically over rev the engine if the bike drops down a gear, say you are at 8500rpm already and you bang it down a gear you will mechanically over turn the engine and the limiter wouldn't be able to stop it.

If you were in third, it popped out, and it revved. The limiter should have kept it from over revving.

This is also an interference motor so if you over rev it, mechanically and floated the valves you would end up with bent valves unless you really lucked out somehow.

TLDNR: doesn't sound like you over revved it.

Sounds like you need to split the cases and fix the transmission and shift forks. Each time it happens the dogs on the gearbox round a bit more and it will do it more and more frequently.