I remember years ago when the Triumph TR7 was the course car, My friend on a Norton Commando 750 was waiting for the roads open car to pass by, then follow it, if he could all the way back to the start. By the time the rope was dropped, after the car had passed, it had disappeared. My friend chased the car in hot persuit, but in doing so for several miles, burned a hole in one of his pistons, which ment we had to try and locate a left hand piston somewhere on the island, as Norton pistons were not the same in both cylinders. We could only locate a right hand piston, and fortunatly of the same bore.
My friend then borrowed an angle grinder of some sort, and roughly ground out the valve pockets of the piston, so it could be fitted into the lefthand cylinder.
It was a bodge job, but it got him back home to Cornwall.

The bodged piston now sits proudly on his mantlepiece, as a momento.