Vapour blasting wont damage bores - it's a non aggressive process. The bores will flash rust very quickly though ( within minutes) due to the amount of water that will be used in the process. I've had plenty of rebored barrels vapour blasted after reboring them first. Make sure you rinse the barrels really well afterwards - the vapour blasters should do that as a matter of course, but I always do it when I get home to be doubly sure, then thoroughly dry, and then oil up the bores to stop the flashing. Once you've got oil on the bores you'll be fine.
I would blast before boring and I wouldn't agree that its non aggressive either, how does it remove shit if its non aggressive, (I have a Vixen vapour blaster), I'd also be very, very careful after blasting to clean the item you've had done, the picture below is what I got out of a set of cases I had done and looked spotless, i run a tap down every thread and pipe cleaners through any holes, the process is fantastic if treated correctly.
I've had probably 7 or 8 cases vapour blasted plus twice that many cylinders over the years, and never had any problems with damage or media floating around a rebuilt engine. I'm not sure about media types with vapour but the stuff both my current guy, and the previous firm use is almost like flour - it's very fine. I'm very careful with rinsing afterwards - I put my parts in the bath, take the head off the shower hose and blast all the passageways out with hot water. All threadways have old bolts wound in before blasting, but I still run cotton buds - lightly greased - down all the holes when the bolts are removed just to be sure. I left some old seals in the first set of cases I had done years back and it didn't damage them at all - the lettering on the seals was still as good as prior to blasting. As with everything, prep is all important, and also finding the right people to do it who know what they are doing and care about doing a good job. The fella I use now is fussier than me - if that's possible !! - and the last set of cases from him that I rinsed at home didn't dislodge any sign of blasting media whatsoever - it's easy to see in a white bath if anything was left. As always, go with what makes you comfortable, but for me, it's not a problem getting them vapoured after a rebore
I'm not trying to diss what your saying Dusty, I have no doubt you know exactly what your doing with your builds and I'm always impressed by them but that debris came out of my professionally blasted cases and even if the stuff is like flour its an abrasive. It might just be me but I don't vapour blast 4 strokes at all after having issues with the Alfa after having its head vapour blasted I chemically stripped the Buell when I rebuilt that.
My brother bought a Z650 from a well known Classic bike dealer some years ago. He paid top money for it. It was newly rebuilt and had featured in Classic Mechanics magazine. He hadn't had it long when it started to make a horrible noise from the engine. It went back to the dealer who ended up stripping the top end to find blasting media that hadn't been cleaned out, had mixed with the oil to create an abrasive mix sloshing around the engine ! He got his money back ! I didn't think you were dissing me - just telling of my experience of vapour. Others may have good reason to do it differently of course, and that's fine The particles in your pic look nothing like what I've experienced which makes me wonder if there are more aggressive medias used in vapour blasting ? I know a couple of guys on here have industrial vapour blasting units. Would be interesting to know what they use ?
I use 150 grit in my industrial vapour blaster, its to achieve an even surface finish aluminium parts used in food packaging machinery and it is quite abrasive, its not what my cases where blasted with, they where blasted by a professional blaster. When I bought my alfa it came with an incorrect alfetta engine in it, I rebuilt it and it was very nice, a while later I came across an engine of the correct period that required rebuilding, I bought it through a specialist in London and decided to let him rebuild it for me and fit the motor because I'd done enough of them, I insisted on every new part under the sun and that everything was to get vapour blasted, he did the work but the engines need running for around 300 miles then re torquing, fine this took weeks because he had to drive it to and from work etc. We had arranged for me to collect a week later and he left it running in the shop for some last minute tuning and it seized, it f**ked everything, cylinders, crank, oil pump the lot and that was blast media.
I do lots of Vapour Blasting and the above photo looks nothing like what I would use, looks more like metallic particles to me
I cannot comment on what a company might use or not use Vapour blasting is none evasive it can be used on machine surfaces quite safely.
As to the removal of blast media, any decent/Professional company should use a 3 stage dip tank then always finish with hight pressure airline before final rinse and clean off.
I have never had anyone say they have had issues if done correctly and Dusty will confirm this as his rebuilds are first class and always gets his parts Vapour blasted. "Suppose if you build engines you make sure they are fit for purpose in your prep and final finish" !
Last Edit: Dec 31, 2019 0:31:50 GMT 1 by shandyboy