Here's my 836cc racer engine I built over 2 years ago. Rather than risk damage to the expensive innards I didn't get the cases blasted, but rather, I thoroughly degreased everything, then again I cleaned up the cases with turpentine and "wet and dry" sandpaper to flatten the old paint, then etch primed them with a "zinc rich" etch primer, then painted with engine enamel.
Luckily I didn't get any fuel on it before the paint had time to "heat cure" when I fired the engine up for the first time, but since then I have spilt fuel on it a couple of times, with no problems, whatsoever.
The factory cases were primed and painted in a similar manner, but Honda was renknowned for using the absolute minimum of paint, (the rumor is that the early K series tanks were never primed, but rather Honda used the silver base coat in the "candy" paint as an undercoat) so it's not surprising that the OEM engine paint started to chip off so early in the bike's lives.
My advice is that as long as you spend plenty of time preparing your engine properly you don't need to get the cases blasted, but if you do, make sure you spend an hour or two cleaning every nook, cranny and internal thread to remove any grit with warm soapy water and brushes, bottle brushes, pipe cleaners etc, and flush it several times, or there's a good chance you'll be rebuilding it again real soon............ Cheers, Terry.
