Topic: Sandblasting engine - answered

[Floshenbarnical]

As usual, a long-winded post to ask a simple question.

My 77 F2 engine is solid enough but is a bit of a mess. The bottom end is enameled black and it looks "fine" but the top end is painted aluminum silver and is kinda #$%*ty looking.

I want to strip the whole motor and repaint the whole thing aluminum silver, and then polish the living daylights out of the covers. I feel like every cafe racer has a matte-black engine and I'm sick of it.

Can I have the sandblaster strip the engine while it's in one piece, or do I need to have the entire thing disassembled?

He claims he can block off ports and crannies using tape and silicone and caps and whatnot. If so, great. However, I'm concerned that media will still enter the motor, which is bad for it obviously.

Thoughts?

[craz1]

In my experience I would disassemble the whole motor. That media can get into the tiniest crevasses. Im Sur others will come and say just the opposite so the bottom line its your engine. I would find a good vapor blaster and just use the finish that it produces. Do not sandblast.

[Floshenbarnical]

Yeah I'm not disassembling so I guess I'll be stripping and sanding.

[pjlogue]

I will caution against sandblasting.  Most certainly double caution you against sandblasting entire engine without full tear down.  I sand blasted my '76 750 engine back in 1984 and regretted it.  When I restored my '76 back in 2016 I researched things and read about vapor blasting.  The sand blast job I did back in 1984 lasted all of about 1 year until the paint started coming off.  The restoration vapor blast job I did is still like new with paint intact. 

With both vapor blasting and sand blasting you need to be very, very careful about cleaning  each piece before assembly.  Vapor blasting will leave a satin like finish.  Sand blasting will leave a very rough finish.

-P. 

[Floshenbarnical]

Good stuff guys. Thanks for confirming.

[calj737]

It entirely depends upon the media type the Blaster uses. Fine glass, Aluminum oxide, etc are good for stripping, easy to infiltrate any orifice. Taping off and blocking ports is about a 95% assurance. That last 5% could bite you badly.

Soda blasting is an option too. That media is more easily flushed. Vapor blasting leaves a "peened" finish and its lovely. The problem is, most vapor blast cabinets cannot manage an assembled engine. Great for parts, assemblies, but not so much for 150#+ lunks of metal.

If you dont want to disassemble, I'd recommend soda blasting. Easy to spray down your motor afterwards, and easy enough to flush out. Does a very good job at stripping withoiut so much abrasion as traditional "sand blasting".

[bryanj]

Dont do it, the media will get into crevices, mix with oil, turn into sludge then concrete then it will block the tiny oilways reulting in a catastrophe

[pjlogue]

what CalJ737 said is also an option.  The blast media will dissolve in water but you still need to clean everything well after blasting.  If this a do it your self project any media you use, you need a respirator and face shield.  Soda blasting will ruin your air ways and any plant life the dust falls on. 

-P.

[Stev-o]

In my experience I would disassemble the whole motor.  I would find a good vapor blaster and just use the finish that it produces.

+1...that is what I did on my last motor rebuild.

[BenelliSEI]

In my experience I would disassemble the whole motor.  I would find a good vapor blaster and just use the finish that it produces.

+1...that is what I did on my last motor rebuild.

+2. Only way to do it.

[Floshenbarnical]

In my experience I would disassemble the whole motor.  I would find a good vapor blaster and just use the finish that it produces.

+1...that is what I did on my last motor rebuild.

+2. Only way to do it.

Good stuff. Thanks for the input everyone. I'll get it sandblasted when I inevitably take it all apart in the next couple years. It's an F2 so I want to have the valves messed with by a seasoned professional.

[MauiK3]

Coarse media is pretty rough on the soft aluminum, careful, it may do some serious damage

[craz1]

I have developed a system to blast cases with SS media and polishing lightly with 0000 steel wool. Very close to Vapor Blasting and I can do it in my cabinet. But you do have to disassemble everything

[Floshenbarnical]

I have developed a system to blast cases with SS media and polishing lightly with 0000 steel wool. Very close to Vapor Blasting and I can do it in my cabinet. But you do have to disassemble everything

Beautiful bike you got there and thank you for the advice.

This year I'm going to paint the cases aluminum gray and polish the living daylight out of the covers. I used to be super into the satin black engine until I saw some of the bikes on here and now I want the thing blinged out wherever possible. It'll match my nice shiny billet aluminum top fork clamp and my shiny new Delkevic headers.

I'm keeping the original JIS screws on the carburetors (those carbs seem to be made of cheese and I'm terrified of stripping holes) but love the shiny socket cap allen bolts elsewhere, e.g. engine covers. I bought a set last year and installed them with anti-gall. Where do y'all go to buy nice fasteneers? I want to replace every crappy, rusty, #$%*ty looking bolt I possibly can.

[calj737]

https://boltdepot.com/

Scroll down on the left and choose metric. There you can find all types of metric fasteners for your particular need.

[craz1]

I buy a lot of stuff from theses guys
https://belmetric.com/socket-products/allen-socket-head/?FilterMaterial=Stainless__Steel&filterPage=1

[Floshenbarnical]

https://boltdepot.com/

Scroll down on the left and choose metric. There you can find all types of metric fasteners for your particular need.

Oh my god this is gold

[ozm29c]

As my engine was in pieces I chose to glass bead blast, etch prime and then paint my cases. For the machined surfaces I made cover pieces out of old sheet perspex. Photos best show the end result.

[jsmith800]

This engine i sandblasted in the booth after total disassembly then powder coated.

https://photos.app.goo.gl/mscR7EyFMc71LWdn7

This engine I had someone vapor hone.  I'm not thrilled with his vapor hone quality but finished bike looks fresh and new.

https://photos.app.goo.gl/XfHZ1fekfsh2w8xg8

Both procedures are susceptible to having media in crevices and threats.  I recommend washing all parts in soap water after procedures and before rebuild.  Also chase and blowout with compressed air ALL threads before assembly.

[Stev-o]

I have developed a system to blast cases with SS media...

What is this SS media, craz?  It sure leaves a beautiful finish.

[calj737]

I have developed a system to blast cases with SS media...

What is this SS media, craz?  It sure leaves a beautiful finish.

Stainless media is an excellent choice for blasting/tumbling alloys. It won’t scratch, won’t contaminate, and does a beautiful job removing oxidation, grime, and paint. Many ammo reloaders use SS media to tumble brass.

As for the so-so outcomes from vapor blasting; not all blasters are equal. Their choice of media, air pressure and liquid ratios determine the finish quality. Simply calling it vapor honing doesn’t ensure equal results (sadly).

[willbird]

This engine i sandblasted in the booth after total disassembly then powder coated.

https://photos.app.goo.gl/mscR7EyFMc71LWdn7

This engine I had someone vapor hone.  I'm not thrilled with his vapor hone quality but finished bike looks fresh and new.

https://photos.app.goo.gl/XfHZ1fekfsh2w8xg8

Both procedures are susceptible to having media in crevices and threats.  I recommend washing all parts in soap water after procedures and before rebuild.  Also chase and blowout with compressed air ALL threads before assembly.

Seems as if it is tough to get a nice consistent vapor hone on a large surface. Some have said that it is necessary to soda blast first then vapor hone after so maybe how even the soda blast is becomes a factor too ??

Bill

[craz1]

Yep Stainless Steel. Two types, on badly oxidized surfaces I use a cut wire with sharper edges at low pressure 50-60 PSI. Then I go back over it with a conditioned wire which tends to peen the surface. Then I wash everything in hot water with Dawn and buff with 0000 steel wool which gives me the desired finish. Not quite as good as Vapor Blasting but I can keep 4
$400-$500 in my pocket. I bought 25 LBS of each type many years ago. I have modified my cabinet. You can clean the media and use it again and again if you're careful. I wont go back to beads for what I do. Don't get all the dust. I use maybe a cup or two at the bottom of my modified booth. I will be doing a set of cases  for a friend for his GT750 Suzuki with some pretty bad cases. I can post some photos. I used to use blanking plates but not any more. But I do use screws in every female thread and tape off bearing surfaces with gorilla tape and cover or plug any passages just so I dont worry about media getting caught. Still have to check very carefully

[willbird]

Yep Stainless Steel. Two types, on badly oxidized surfaces I use a cut wire with sharper edges at low pressure 50-60 PSI. Then I go back over it with a conditioned wire which tends to peen the surface. Then I wash everything in hot water with Dawn and buff with 0000 steel wool which gives me the desired finish. Not quite as good as Vapor Blasting but I can keep 4
$400-$500 in my pocket. I bought 25 LBS of each type many years ago. I have modified my cabinet. You can clean the media and use it again and again if you're careful. I wont go back to beads for what I do. Don't get all the dust. I use maybe a cup or two at the bottom of my modified booth. I will be doing a set of cases  for a friend for his GT750 Suzuki with some pretty bad cases. I can post some photos. I used to use blanking plates but not any more. But I do use screws in every female thread and tape off bearing surfaces with gorilla tape and cover or plug any passages just so I dont worry about media getting caught. Still have to check very carefully

Some of the engine builders use a bake oven first on cast iron parts, then a machine called a wheelabrator that uses a flywheel to hurl steel shot at the part, much too agressive for our parts tho. It sure does a great job on steel and cast iron tho. One prior employer warm formed aeroquip fitting blanks and we used a wheelabrator on them.

[craz1]

Yes I would say hurling shot at our cases would be pretty hard on them.