I recently had to trouble the RNLI after my Yamaha 30 came to an abrupt halt. A piece of impeller had wedged against the thermostat causing it to overheat.
This is the second engine I have killed in a month or so.
This is the thermostat along side the new one:
And the pistons:
The 'scratches' on the cylinder walls weren't enough to catch a fingernail/credit-card so I have taken a chance on honing (that I knew wouldn't remove the scratches) and new pistons and rings. New Old Stock standard pistons were available at good prices - oversize pistons were really expensive.
Fool's errand?
Honed cylinder: