850 Head Job

Nice job on the head there Mick, you cant beat Hydroblasting for a better than new finish. Hydroblasting is fine glass beads in water and the results speak for themselves. My Norton head has copped the same treatment, looking for some time off to get the cases & G/box done now!
Incidently,just as a precautionary measure, any engine or gearbox/trans parts that are hydroblasted or just bead blasted, I believe should be heated up (before assembly) to release any glass beads that may have embedded themselves in the metal
(internally of course). We dont want that stuff coming out and contaminating the oil, makes for a good grinding paste! When parts are in the ol'girls oven you can hear the glass beads release. I tell my wifey if she goes off at me, shes sounding like an ex-missus!
Foxy

People ask: Does a vapor blasted head look like its been painted silver??? No doubt about it. That's the comment I get most often from guys who have never before seen clean aluminum and don't know what it looks like. A vapor blasted casting looks silver, like it just came out of the foundry, before it went onto that filthy assembly line. Old-time dealers tell me, "The bikes never looked that clean when we opened up a new bike in a crate!" I know; they were already dirty when they were crated.
You will also see that vapor blasted studs get about 50% of the cadmium plating blasted off during vaporblasting. Not a problem. You'll probably be cleaning and repairing all those cad-plated fasteners and then sending them out to your local helicopter shop for cad plating before you reassemble your engine.
If your vaporblasted engine looks too clean for you, don't worry. Just spray it with WD40, it will get a little dusty, and you'll be happy with the results.
Have fun with your project. Jeff G. at www.vaporblasting.biz

No thanks on the glass beads. Don't they splinter and wind up in all the nooks and crannies?

In the USA its called vapor blasting or liquid honing or hydro honing. In the English-speaking world, it might be called vapour blasting or acqua bead blasting.
Its all the same: parts are blasted with a slurry mix of the finest glass beads suspended in water and detergent and accelerated by compressed air. Some guys claim their process is so secret, that they deserve to charge more money, but its no secret. Vaporblasting has been around ever since WWII.
Nice work. I'm Jeff G. at http://www.vaporblasting.biz

The only thing I can think of that would do that kind of upper piston damage would be an old worn out amal chunk of slide fracturing and getting in the combustion chamber. Luckier people have the chunk blow straight out the exhaust port immediately. Nice clean head.