This happened back a great many years ago, around June, IIRC.
Driving North on the M6 around the end of the Lune Gorge (roughly) on my 1960s AJS motorbike, doing about the speed limit I decided that the view of the waggon I had been following was getting boring, so I started to overtake.
About 2 / 3 of the way alongside it, there was an almighty bang and the engine stopped.
I snatched the clutch in and used my right hand to indicate going left / slowing down and headed for the hard shoulder...
coasted down it until I found a phone.
Stopped and put the bike on the stand. Quick examination - smoking oil up behind the cylinders and seized completely solid.
After I stopped shaking, I rang the motorway control to report my presence and to request the AA send a relay (don't bother with the roadside inspection, it ain't fixable, they still sent a mechanic, who agreed with me at once).
Police patrol checked I was OK a couple of times while I waited for the relay. (went to relative's large garage, arriving very late at night)
Surprisingly, there weren't skid marks on the road - I went and looked a couple of days later).
Turned out that she'd put a leg out of bed.
The big end was almost opened out flat and that had punched a hole about 2" across in the aluminium crankcase on the affected side. Cause was some old red hematite sealant from a previous rebuild (not mine, I used high temperature gorilla snot) had blocked an oil way.
Bike was put back on the road, after a lot of work - and a fight with some twats that bored one cylinder oval and not vertical. Getting that sorted was the most difficult part of the rebuild. The next time she needs a rebore; it will have to be a relining.
I went round the Beamish Trophy route that autumn on the same bike.
The life and times of my beloved 1960s AJS 650 twin ...