It was time for the 7500 mile service on my 750, so I'm taking a look at the schedule and...
Lets see... Air and oil filters are good for 11250 miles, but the plugs, iridium plugs at that, are only good for 7500 miles?
Same sparkplugs as in my Krap-a-saki Versys; on that bike I replaced them at 38,000 miles... When I was replacing the head, after the thermostat failed and the head warped to hell. Might as well throw in a couple new plugs when you're at this point, right?
But how did the plugs look? They were worn, definitely, the ground electrode (cathode) is nothing special, only the electrode (anode) is coated in iridium. In the picture is noticeable how the cathode is worn but the anode is like new.
Next time I won't wait 38,000 miles to do them, but 7500 miles is just a waste of money. I plan on replacing them at 22500; I'll report back whenever I get that far on my 750, that is, if I get there, bike ADD is hard to resist. In the Versys I'll get there soon, it's my commuter and tourer, but I doubt anyone here cares about the Krap-a-saki, no to mention that engine revs slower so it puts less wear on the plugs.