~
Count me in the "DON'T USE S-100" camp. I tried it, didn't like it... Had friends tell me to try it again, and still didn't like it. IMHO it's just too caustic for many finishes used on motorcycles. I've had much better luck with just mild liquid dishwashing soaps, and believe it or not the old "Mr Clean" vehicle cleaning kits were pretty damn good.
OTOH, I'm sure most all of you know this, but good ol' WD-40 is one hell of an engine cleaner. Hose the bike off, let the water run off a bit, then douse the engine with WD-40 and let it sit a while, then rinse it off again. Amazing how well it works for that specific application. Just don't do when the engine's hot. Of course you should never be washing the bike, and especially the engine, when it's hot. Once you're completely done with your bike cleaning dampen a rag with WD-40 and wipe the engines surfaces down and it'll be a lot easier to clean the next time, even if it's weeks later.
Been using it for decades and never had any ill effects.
Just FYI... YMMV.
Dallara
~