I didn't have a lot of time to tinker today, but I did manage to pull the spark plug and plunge the business end of my Harbor Freight Inspection Camera down in there for a looksee. As you can see from the attached photos, the plug looks pretty reasonable, but then it's only a few weeks old. As for the top of the piston, I'd say it's about as coked up as Steven Tyler's nasal cavities in the hotel room after a '70s Aerosmith concert. One imagines the head and valves must be similarly grimy.
So, for the time being I got a spray can of SeaFoam with one of those clever tubes for injection into an intake manifold vacuum hose or port and one of the bottles too. I sprayed just a bit into the spark plug hole, buttoned it back down and kicked it over a few times. I did this twice, the second time with the decompression lever engaged in order to let it get all up in there. Now I'm gonna just let it marinate until nicer weather is said to return in a couple of days. I also dumped about 2/3 of the bottled SeaFoam into the fuel tank as a sort of shock treatment. Lots of folks do this as a quick Spring Shock Cure for the "ethanol snots," stale crap fuel having often mucked up the system over the winter. I imagine a little overdosing might also do my combustion chamber the power of good and perhaps help trim down at least a few of those black stalactites.
On Wednesday or Thursday I'll pull the decompressor assembly off to see what's going on there, clean it up, adjust as necessary, re-install it, and then fire her up. Once she's warm, instead of pulling the air filter assembly, I might just rig up some reasonably airtight hose from the spray can SeaFoam into the little Pulse Air Valve vacuum hose port on the underside of my intake manifold. Bit by bit I'll empty the can and then stall it with the stuff for a good hot soak for a bit. After a quick run I'll then see how she looks.
Plan B is that I might break out my little handheld steam cleaner for drapes and upholstery and such, jam its little nozzle into that PAV vacuum hose tube off the intake manifold, and just let it and the bike run together for a bit. Nothing gets a combustion chamber so squeaky clean as
water injection.
Plan C is to probably repeat Plans A and B...maybe a couple of times.
Plan D is to be a man, and pull off the damned head already.