In the old times (when I used slimy power plants) nothing worked better than "Top Job" and water (much better than dish detergent). Now it is sold under the name "Mr Clean" leaves the monocote shiny like new.

It also works on gas engines, but they are not that messy

To clean my electrics, after the flight, you want to shake off all the watts and amps that might stick to the airframe during the flight:-) I actually clean the dust off my the electrics before going to the filed...

Gerry