I popped the cleaned throttle body back on along with new rubber seals and bellows last night (and new rocker cover gaskets as they were a bit leaky). I bit of a pain to align the manifold air pressure sensor, the choke (yes I know, not a real choke!) cable and the various other wee bits and bobs so that they fitted under the head steady or between the head steady and the injectors, but I got there. I also check down the spark plug hole whilst the tank was off (access to throttle is far easier with tank off - not necessary but less cut hands!) and noted that the top of the piston was just as black as the throttle was
A wee poke with a flat head screw driver lifted some of the black deposit up through the plug hole. Mostly soft carbon like deposits, similar to some bits of the throttle body (especially the airways), but there was also quite a caked on hard black material under this softer stuff. Having not pulled many engines apart (except for clean ones in college) is this bacl build up something to be expected given my throttle was in a similar state, and will it burn off when I get the mixture right? Or should I be considering a head off, decarbonizing task in the near future... or perhaps an Italian tune up?
BTW I could take the bike out for a test run, but it idled nicely in the garage when I reconnected the battery etc.