Next Rebuild CT70K0

[kirrbby]

We have a 50lb bag of walnut shells here at work. As it's sitting, I measure it to be approx 18” tall x 14"x12". So I'm thinking 10lb ain't much. I'd bet you'll need 3, if none is being captured. I would blast it inside of a cardboard box so that you CAN capture some of it for a second go. Then, maybe only 2 bags..?

Another option would be to contact fatcaaat, ask him about vapor honing it for you. But you'd have $25 just in back and forth shipping...plus labor.

I would actually like to see how well the shells work. I plan to buy a small cabinet to dedicate to walnut/pecan shells...just for cases and heads and such...now that I have a good big air compressor to run it.
A small harbor freight type cabinet is less than $100. Then...10lbs might do it.

 

[JHminitrails]

Glass beads....vapour blasting.....it's all glass beads hitting your parts. One is dry and one is wet. Why is one ok and not the other??? It doesn't make sense. I've have glass beaded lots of motor parts over the years and still do today. If you use common sense and are thorough in your work, all media can be removed and cleaned out of the components without future problems. I don't see an issue with low pressure glass beading at all. And it leaves a fantastic finish in my opinion.

 

[Robert thran]

All the parts I had vapor blasted have more of a shinny shean then just glass and don’t stain compared to just glass beading,,,, anything that gets on them just wipes off real easy..you do have to spend more time cleaning all the residue before the build. At work I have a 55 gallon open vat of mineral spirts that I use to super clean with an air blower under the mineral spirts,,( parts submerged) it pressure blasts them clean pretty easy…..this is just my 2 cents

 

[hambone]

I glass beaded the head on my SL70, it didn't turn out bad, I taped it up well and didn't get too close. I do want to try the shells, I'm going to buy a bag and see how it goes, like Kirby said, $100 cabinet dedicated to shells would be nice, I will have one soon, saving for OldCT's parts right now, having to drink natty boys. lol!

 

[OLD CT]

So yes, the key is like Robert said, be aware about ''cleaning out'' all the places where oil runs thru, I used a parts washer and pressure back when I had access to a blaster and a safety Kleen tank, with the old hot sauce. They have eco friendly crap now. I want to see how the shells work out for you. ☕

 

[kirrbby]

Search results for query: Blasting cylinder head

lilhonda.com

 

[Gary]

Part of the problem with blasting IMHO is being in too big a hurry and using too high a pressure. I have some plastic abrasive but never got around to trying it. https://www.tptools.com/Skat-Blast-Skat-Plus-Plastic-Abrasive,10580.html?b=d*8020 Did this head with beads years ago, been happy with how it turned out.

 

[Gary]

Also got a double nut stem tube for my 50 a few years ago from kirrbby. It had rust stuck to it from the typical rim rusting that I just couldn't get off. Threw it in the cabinet on a whim, worked great too.

 

[JHminitrails]

Part of the problem with blasting IMHO is being in too big a hurry and using too high a pressure.

Did this head with beads years ago, been happy with how it turned out.

I agree Gary. Slow and low pressure with fine grit glass beads in a dry media cabinet works great. Your head looks just fine in my opinion. These are pics of my K0 motor I did last winter. The finish on the cases isn't far off of what the new E22 head has. I wanted to try one of DrAtvs big dome heads as I needed one for this motor. My only beef with it is the goofy looking circular casting marks on it. I should have filed them off and glass beaded the head, but that's hindsight for ya!

 

[kirrbby]

Racerx would always caution against sandblasting aluminum parts. Changing the "as cast" finish. Removing metal. Creating a rough, dirt catching, and porous, surface.
He seemed to speak from experience, and was convincing.
The as cast finish matters to many, when attempting "correct" restorations. Blasting, no doubt, ruins that finish, and it never comes back. If that matters to you.

Blasting cast aluminum can also open up the "pores" of the metal. Allowing dirt to go deeper, when it goes on. Kinda like polishing a apple with sandpaper...then trying to clean grease/grime off of it.

I've never turned the pressure down on my blaster...so no experience there...but it sounds like a very good plan if you have to blast a head.
I've never had a vapor honed part in my hand...but from what I see and hear...I think it's pretty hard to beat...and, looks significantly better than dry blasting when trying to maintain a correct looking cylinder head. Just my opinion I spose.

Walnut shells...according to Bob, doesn't destroy the as cast finish provided that ONLY shells are used. That would require NO glass grit, no sand and crap from the part...no rust from the part, is allowed to get into the mix. But using shells only, might never be able to remove all of the staining and such. So if you want perfection, you might have to follow the shell blasting with elbow grease...chemicals...whatever. But IMO again, the variation of color and surface smoothness, on a cylinder head, IS what looks "correct" to me. The perfectly uniform color and finish on a blasted or vapor honed head, is what tips you off that it's no longer "as cast". I often find that I'm zooming in, on a part that's been vapor honed, to see if it is actually paint. It's THAT uniformly smooth and colored.
We all, only, have to please ourselves. But what pleases you might not please your critics.

 

[OLD CT]

Well, there ya all go! That's it in a walnut shell. Couldn't have said it better Kirb. I get a kick out guys that think they are purists 100% concours and still vapor blast glass bead or sand media blast a head. I am NOT a purist, but I always recommend purist values first. You do your thing, I do mine.
Please yourself.

 

[kirrbby]

As long as I have some time to keep plinking here...I KNOW y'all want to hear some MORE of my opinions 😵‍💫

Engine cases are typically pretty smooth from the get. Blasting them makes them rougher than they used to be. But it makes them rough enough that you can then begin to sand, scrub, or Scotch Brite them smoother...pretty easily. I like to scotchbrite and wd40 blasted cases,or covers. I think the result looks pretty nice, and smooth.
A fine brass brush, plus wd40 is really good too...whether you blast first or not.

If you dryblast cases...opening up the "pores" then you spill your coffee on them...I'd guess, that the coffee might stain them. Coffee has very fine particles in it that could wash into the pores. Greasy fingers might stain them too..?
But if you oil up those freshly blasted cases, with clean oil...the pores are filled with oil before the dirt can go in. Then the dirt it easier to clean off...since there is a oily layer underneath.
Clay dirt..."red clay", baked into a dry...non oily...aluminum surface, is the most difficult to remove without blasting, IMO. I think the fine particles in clay are able to get into the pores of the metal...then, I think it must be somewhat acidic, or something, that allows it to attach to aluminum. It's almost like a dirt stain, rather than just dirt.
I oil EVERYTHING, before I send it out to get dirty. Even if it's chromed or painted. Get some clean oil into the crevices and cracks and pores before anything else can get in there. Then clean it off and wax it if ya want.

Dirty, stained cases are far easier to scrub clean, and/or polish, than a finned cylinder head. You need all the help you can get to keep the head clean. If you blast it...have a plan to maintain that clean look.

 

[JHminitrails]

No matter how much of a purist you or we are, once the bike has been restored....it's now a restored bike. Period. All originality is gone the minute the first part is replaced or the first part is repainted. So glass beading or vapour blasting cases and a cylinder head isn't hurting the purist value anymore or less than a new seat cover is or repainted wheels. As kirbby and Old CT mention, it's about pleasing yourself and achieving a result that you're satisfied with. And F@#% anyone who wants to criticize your work! If they think they can do better, then I say show me your work. And then see how they like their hard work, research and money spent ridiculed....I bet their attitude changes pretty quick once they realize the effort and time it takes to restore or build a bike of any kind. Let's face it, we are dealing with little honda playbikes here, not Ferrari F40's or first generation Bugatti's! Our bikes AREN'T all that rare. Please yourself and enjoy your projects.

FWIW for comparison sake....this is a head that I just picked up from my machinist. Had seats cut and had him vapour blast it for my own curiosity. Personally it doesn't look or feel much different than other parts I have glass beaded. Yes it looks great, but I wouldn't pay for it again when I have my own cabinet and can achieve damn near the same result.

 

[hambone]

Damn!, that's some great info, my head is hurting now, lol!, Kirb, I didn't realize there was that much info out there, I read thru a lot of those threads. First attempt will be with shells, I will post pics of results, I need to give it a good degreasing first. You see what I'm working with, so perfection is not a concern, whichever way I end up going will fill my satisfaction, I'm not looking for concours, just a nice looking runner is what I'm after.

 

[kirrbby]

I am NOT a purist, but I always recommend purist values first.

That's me too OLD CT.
I have my opinions of what IS purist correct. It would be all but impossible to achieve. But I think FIRST, we should be informed. To know what is, or isn't, considered correct, by...whoever is judging, should be first goal. I always gave Bob HUGE props for how he would restore each part of a bike, BACK to correct, if he was able. To the best of his ability. If he could restore a fender himself, for the same overall price of buying a new one, then he would.
Some folks strive to collect EVERY needed part in NOS condition. Then repaint/ refinish the matching frame and engine. That's a different kind of restoration...but maybe even MORE impressive here in 2022.

I always like to say...TRY to make it perfect. It isn't possible to achieve perfection, but if you at least try, the end result will be closer than if you had never even tried.


But if you don't know what IS perfect, you don't stand a chance.

 

[kirrbby]

Y'all want MORE??!
Ok then...here we go.

There are rare occasions when I can just delouse a head, or engine cases...then drop them into my ultrasonic cleaner...with the right soap, AND temperature...and they will come out looking pretty fantastic. Fantastic considering how easy that is...but never, simply, fantastic. And again...rare occasions with THAT.

I think a cylinder head might look pretty good if you would blast it...then tumble it in a vibratory tumbler. OR, just polish the tips and flats with a polisher/wheel.

Not correct but, LOOK nice...compared to baked on dirt and stain...and pretty easy vs trying to scrub it clean by hand.

 

[OLD CT]

Heads are tricky to get clean. I have never blasted the cases on any engine build, ever. It just takes time with a good parts washer brush, diesel nowadays and you can get them looking just fine. I do not have access to the Safety Kleen tank anymore. I really enjoyed seeing the mighty green CT70 re finish that Mike's Minitrails performed but didn't restore the engine or try to fluff it up. Now how many of you remember the ct70 engine rebuild guy on ebay years ago? 78dodge was the ebay handle.
He used to ''restore'' engines for members here also. The guy blasted heads and didn't clean out the head properly. One member fired the bike up after farming out a build to him and it quickly shut off on a nice HK1 restoration. He took a pic of the sparkplug and said ''what is this'' stuck between the electrode and ground.
I said that's sand blast media! He was not impressed with the shiny build after that. It was more than one complaint from his work.

 

[hambone]

Been degreasing the head, I haven't encountered on of these valve seals before, I think I ordered a new one, will it just pop out with a pick?

 

[hambone]

I figured it out, that valve guide has a sleeve over it.

 

[OLD CT]

That's the valve stem seal holder, it has a washer that semi-holds it in place. The smaller valve spring really holds in place