Question about stopping an automatic engine ?

Is it better to stop the motor in Neutral or in Drive with the kill button ?

Dont think it matters as in low rpm the clutch is disengaged any way, best practice is probably neutral tho.

The manual says to only use neutral when starting the engine. At all other times we are supposed to leave it in drive.

I stop mine in drive, and leave the system engaged until I want to start it next. Less chance of me forgetting to engage it again when I park it up and the cable getting stretched.

Good question.

VMX Magazine issue #42 has an article on Husky Automatics. Which you probably have seen.
He says... "I'll say it again, the transmission should only be disengaged when starting the bike. At all other times, including when not in operation the transmission should be engaged."

To be safe, I leave mine in drive all the time except when starting.

I tried to coast at more than 40 mph by putting it into neutral. It did not disengage and also did not damage anything. That was a 430 which I believe is a later engagement design than the 390 if it makes any difference.

I do not recall doing anything but hitting the kill button and then putting in neutral later when it came time to start. By the title I thought the topic might be what to do in a two cycle run away scenario.

Yes, when thinking about it, it does not matter if the motor is on N or D.
But When I move the bike in the garage, I prefer to put it on N.

I always leave the early(spring operated) transmissions in gear, the later, post 80,( lever operated) it doesn't matter