Along with pledge for shining the bike, there are other products available for the black wrinkle finish on the motor that work well to restore the showroom look to the cases.
Two that I have used and they both work well are "Pig spit" and "S100 Engine brighter". They are a silicone product and work well also last a while too. I use the straw applicator to spray the cases avoiding excess on the chrome. It wipes right off but used sparingly on just the cases is much easier.
Just spray it on the cases and leave it, no further attention is needed. Any excess on the chrome can be wiped right off.
Two that I have used and they both work well are "Pig spit" and "S100 Engine brighter". They are a silicone product and work well also last a while too. I use the straw applicator to spray the cases avoiding excess on the chrome. It wipes right off but used sparingly on just the cases is much easier.
Just spray it on the cases and leave it, no further attention is needed. Any excess on the chrome can be wiped right off.