Engine Soda Blast after Sand Blasting

[AlphaDogChoppers]

You pretty much have to go nuts with cleaning after blasting engine parts. I use Simple Green and hot water, followed by dishwashing detergent and hot water. I blow out all passages multiple times with compressed air, between each washing. I have a narrow tube on the end of one blow gun that I can insert into bolt holes to blow out debris from the bottom of the hole out. I shoot carburetor cleaner into all of the nooks and crannies and oil passages, and blow out with compressed air again.

It's a royal pain in the ass, but if you want to powdercoat an engine, sandblasting is what you have to do. The cleaning afterward is burdensome, and you have to be extra anal about it.

 

[SmotoBobTT]

@Tim wanted to jump in on this very old thread as i was searching and your comment it unfortunately where i am at> I was rebuilding my top end and found a bunch of issues and remembered that i had this nicer looking head/rocker cover. I lapped and masked the faces with out thinking too much of it threw on the black but it looks like the prior owner i think had either blasted or just painted this Silver color on the mating surfaces. Can you or anyone with more experience confirm that i would need to have them dressed/resurfaced or is this just a minor sand on a flat surface.

(*also for reference the cam in these heads run on actual bearings so even that surface which is curved "U" seems to be blasted or painted)
1976 Xt/TT 500

 

[Tim]

I guess I'd have two concerns. The mating surfaces of course you don't want to leak. A layer of paint wouldn't likely cause issues with a gasket and perhaps some strategically applied sealant.

But depending on the paint used on the interior, I'd be concerned about it coming off with exposure to oils etc. in the engine and clogging passages. Odds are it would just dissolve, and the 500 engine is pretty bullet proof/easy to tear down and rebuild as necessary, not that anyone wants to do that.

Maybe try some solvent to remove the paint on the cylinder head and see how easily it comes off / how smooth the mating surface is. It looks a bit 'textured' but that could just be the paint.

 

[adventurco]

Are you sure that is painted, or just vapor blasted? It doesn't look like a painted surface to me.

Get a piece of glass from an old picture frame and stick some 600 grit paper to it and clean up the mating surface a bit. You'll be able to tell pretty quickly if its paint or not.

 

[irk miller]

Picture frame glass is too thin and imperfect and conforms to the surface it's placed on. If you want to have a low-tolerance true surface, it needs to at least be thick tempered glass if you don't have access to a surface plate.

 

[SmotoBobTT]

Are you sure that is painted, or just vapor blasted? It doesn't look like a painted surface to me.

Get a piece of glass from an old picture frame and stick some 600 grit paper to it and clean up the mating surface a bit. You'll be able to tell pretty quickly if its paint or not.

i am starting to think the same i tired some paint stripper and that did very happily take of my black i painted but nothing on the silver parts. Was actually leaning towards the glass sandpaper idea for the non important rocker to head *as the bearing runs in the head directly and a machine shop for the barrel to head surface.

Weirdly the local motorcycle shop was no help and i tried a paint removal disk and that did literally nothing.

Thanks for the comments

 

[teazer]

It's hard to tell from a photograph, but that looks more like corrosion that was glass bead or walnut shell blasted to make it look clean. If it were mine, I would wet lap it with 600 grit on a surface plate and see what it looks like after that.