Rode 25-30 miles with one busted spark plug... did I mess up my engine?

[Old Jock]

I'd just put in a new plug and try it

I've had ocassions where one of the Guzzis lost a cylinder and just rode it home, stopping to investigate in the middle of nowhere with few tools wasn't the preferred option

Once rode an old T160 Triumph Trident, that broke a tappet outside Birmingham, home to Glasgow on the remaining 2 cylinders, that's around 300+ miles.

The bike was fine and later when it holed a piston (different cylinder) a long time later and I had the head off, the bores were in good condition.

That's not recommended of course but a lot of the well meaning advice posted would have you doing a full engine strip, or leave you worried that you'd permanently damaged the engine.

My advice (for all that's worth) is to put in a new plug ride it, I think it will be fine. If it's not then start to investigate further.

[Road Rocket]

They don't because they don't know which cylinder is dead. The Lambda turns on the CEL because it knows a cylinder "bank" has a misfire or no fire but not which one. I don't know of any motorcycle or automotive efi that does what you suggest. When you interrogate the CEL logged code it will throw a code for "misfire bank 1 or 2" etc such as P0300 or P0312.

Ciao

Of interest to our conversation....Fro m an independent  engineer who I asked about injector deactivation......."I do not believe the OEM uses that strategy for an ignition failure. Most OEM and many aftermarket scan tools have the ability to do a cylinder balance test by turning off the injectors to diagnose a missfire. Technician commands the injector off and observes RPM drop. The OEM diagnoses a missfire by using the crankshaft sensor to watch the speed of the crankshaft, and missfiring cylinder does not accelerate the crank at the same speed a firing cylinder does. It is very accurate, often this system can detect a weak cylinder when the driver does not feel a missfire."

[lucky phil]

Of interest to our conversation....Fro m an independent  engineer who I asked about injector deactivation......."I do not believe the OEM uses that strategy for an ignition failure. Most OEM and many aftermarket scan tools have the ability to do a cylinder balance test by turning off the injectors to diagnose a missfire. Technician commands the injector off and observes RPM drop. The OEM diagnoses a missfire by using the crankshaft sensor to watch the speed of the crankshaft, and missfiring cylinder does not accelerate the crank at the same speed a firing cylinder does. It is very accurate, often this system can detect a weak cylinder when the driver does not feel a missfire."

Yes this is true of later systems/more sophisticated systems and i'd forgotten about that. Earlier simpler systems when the lambda senses excess O2 in the exhaust makes the assumption there is a miss fire. I'm not aware of any that kill the injector though. Yes testing equipment can do as you've outlined. Misfires happen regularly and the ecu counts them over a time duration. If they exceed the limit then it throws a CEL. On my car with the access port installed you can see the live misfire count and log it if you like. On a DI engine such as it has there is always something esp at idle speeds when cold. 
Ciao