Or the newly rebuilt A65 engine (not mine) with the spark plugs out in the workshop just waiting to be timed before being fired up, and the little boy exploring the workshop who thought secretly dropping a few 1/4 inch half nuts down each hole would go unnoticed
It did for a couple of hundred miles....and then knock knock rattle rattle and into the support van it had to go.
The "evidence" found when the bike got home was hex shaped impressions all over both pistons and the head.......and a smaller pile of nuts on the bench.
The total repair bill will depend on whether there is big end damage
At time of writing the little boy has yet to be "interviewed".