cleaner or alternative

I have used S100 for cleaning bike from some local suggesting with decent success (willing to get more advice on this). However, I have also noticed some corrosion on bolts (look at photo for example). Should I just use something to coat with oil after a certain amount of washes or change...

Hey I dont have my air compressor handy.. So I was wondering if I can do the same trick I did to my V65 magna- Pull the low speed carb screws and just blast in some b-12 chemtool carb spray.. then re assemble.. Will that work as a decent alternative to the "shotgun" cleaning method? She runs...