Britbike forum Forums Thread Like Summary - Vapor blasting engines? like it?

I am meeting up with a new local shop doing "Vapor Honing" he calls it. From what I've seen and heard this is the way to go for making our English engines look real nice and stay that way. I'm wondering what you guys thinks of the process. Any suggestions as to what I should ask this shop so I have confidence the jobs going to be done correctly? He says he has done many motorcycle engines and that the process is by far superior to other methods.

I especially like it for when you need to replace the valve guides. Cleaning the head, ports, and old guides BEFORE they are removed reduces the chance of scoring the valve guide holes with carbon. No searching for bits of media in every nook and cranny either.

Cheers,

Steve

I had my engine case hot washed before vapor blasting and after too. I have a machinist with a spray washer which is basically a giant industrial dishwasher. The parts are very hot when they come out.

Muratic or Hydrochloric acid is not advisable for use on brass unless you are very careful and stop as soon as the surface corrosion is gone, once the surface crud is gone it then attacks the zinc part of the brass faster than the copper, hence why the brass takes on a pink hue after treatment. You then have to polish the brass to remove the high copper surface to take the pink hue away. Better to use an acid that will attack the zinc and copper equally, so citric acid is a better alternative. Acetic is not a good alternative as it goes for the copper over the zinc.

Another advantage of citric acid is it will create surface passivisation, which allows the surface of brass to resist staining by handling residues and atmospheric contaminants.