When you say abrupt stop do you mean lock up? In the past the bike has simply stopped running, but the lead up to this is the stuttering/and staggering, what seems like misfiring or something. It goes from smooth to rough in acceleration, and this is usually the precursor to the inevitable engine shut off.
Is a tightening up of the motor the feeling of jerking as opposed to smoothness?
I could find someone to compression test it. I aim to do compression and bottom end testing asap.
In terms of spooge, there is only ever one drip or two hanging from the end of the pipe.
Now that I shut it off before it stalls I find it kick starts immediately after stopping. The bike turns over almost first time every time, hot or cold. Post top end rebuild I haven't let it get to the point during a ride of it stalling/shutting, so I can't say for sure how it starts after that.
What are the chances of this problem being electrical? As far as I know it has all the original ignition parts.