Restoration tip from Vic World

[Steve Swan]

Sandcast CasesSaturday, February 21, 2009 10:55 PM
From: "Vic" <world@ml1.net>Add sender to ContactsTo: sandcast232@yahoo.comCc: sfauctions@optonline.net
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Hi Steve,

Vic World here. I am writing you to point out something, that the first
time I heard it (from Kevin Dodge), I could NOT believe that Andy Morris
had said it!...and that was that he didn't think that the engine cases
were originally painted from the Factory.

Well, now, I find out that apparently you are of the same thinking!!

Anyway, just to set the story straight about this, I have personally
bead blasted Many sandcast cases, each time watching the original paint
flake off!

It can APPEAR that they weren't painted (as first, the surface is quite
rough of course), and as well, as we all know, Honda didn't pile a lot
of paint on anything back then! Most parts were covered with a very
light coat.

It only makes sense that they would have painted them, just for the mere
fact of trying to achieve some sort of longevity out of the parts. If
the cases WERE bare aluminum, then all of Honda's customers that lived
near either Coast, for example, would be returning to their Dealers
within months with nasty corroded looking aluminum on their bikes.

And if they WERE going to release motorcycles having any bare aluminum,
they why would they have gone to all the trouble to clear coat all of
the OTHER aluminum parts for each bike? (Rear hub, brake backing plate,
front hub, forks, etc.)...as well as of course the (by your own
admission) the cylinder head, and cylinders!

You can be sure that Honda painted the cases, and one of the best places
to verify this, is just check inside the starter motor well, where the
cases have had very little exposure to the elements. You'll definately
see paint there every time.

Anyway, great website still..and a nice job on your early bike!

Thanks much,

Vic

Ohhh...By the way, heard that you gave a good review to the folks at the
AMA regarding my restorations, and wanted to say that was very much
appreciated.

[Steve Swan]

Hi Vic

Since I know of several SOOC members other than Andy Morris who've reported paint not on sandcast crank cases, I am posting your email for the general benefit, view and comment by fellow members

One thing we have learned, with the sandcast CB750, there are no absolutes in every aspect of sandcast CB750 characteristics and ancillaries. When it comes to the earlier vins, these details are even more variable and obscure.

Speaking for the lot of us, some of whom have been in very frequent and regular contact for over five years, we have discovered in our first hand comparisons of specific vin's parts, some very definite and consistent features wthin the vin ranges, not elsewhere noted in period Honda literature we are aware of.

We are collecting a body of information and knowledge, based on first hand experience or witness supporting various features, aspects and ancillary parts characteristic to what one could expect to see within specific vin ranges.

I have no doubt you've seen paint flake off sandcast cases.

As well, I have no doubt other members (myself included) have seen no trace nor signs of paint on sandcast cases that are obviously unmolested since they left the factory.

In order to say all cases were painted or not painted, someone would have to examine every set of sandcast cases produced by Honda.

I have to trust member's (including my own) observations the crank cases they have seen having no sign nor trace of paint on them. At least three members, myself included, have been restoring, for over 4 decades, motorcycles of many different marques from the turn of 1900 forward. So, i am very confident their observations are accurate, experienced, disciplined observations.

As to the rationale Honda had for clear plastic coating ancillaries, in particular the polished parts, i can only assume it was to protect the lustre.

As far as why Honda possibly painted some sandcast crank cases and not others, it's entirely possible. Members have reported inconsistenicies in other manufacturing details.

While I've not seen the number of sandcast cases you have seen, I have not yet to date noted any natural finish on any set of sandcast cases to be severely oxidized or stained. I've looked very closely at sandcast cased engines that have sat outside for decades and the cases were not oxidized and had no trace of anything looking like paint.

Not that you don't have a point, with the extreme costal climactic conditions, but even in a short period of time, a "very light coat of paint," would not remain intact that long nor withstand repeated exposure to chemicals.

Glad to give a good review of your work. Your attention to detail is second to none.

Vic, hope to hear from you on this forum. We'd love to have you participate.

I am sure you have knowledge of many details that would prove fascinating.

Sincerely,

Steve Swan

[mrhonda2u]

Hi Chris,

Thanks for your response and info. When I said "paint flaking off" ...I
didn't mean that literally. What I meant exactly was that whenever you
bead blast a part that has paint, you can see the paint simply "shedding
away", exposing the bare metal, versus, bead blasting just dirty metal,
where it just appears to merely come clean. My blast cabinet has a
really strong filter/vacuum, whereby the parts cleaned are never
obscured by particulates or blast media flying around ...(wasn't so,
with my earlier cabinet!).

I had spoken with Bob Hansen today (who you know Invented the CB750 with
Mr. Honda), and I relayed the possible consensus out there that "some of
the cases were painted, and some were not"....And he basically just
laughed!...Asking me that if I could envision buttoned up crankcases
coming down the Paint line, and that possibly the painter would go out
for a cigarette break every so often, and maybe the cases just kept
rolling down the line (while he was outside smoking), and then when he
returned, he started painting cases again!...thus missing a dozen or two
motors in the meantime!.....

The preceeding was a joke , by the way.

Knowing Honda's attention to detail, and EXCELLENT, (and advanced)
manufacturing processes, we really had a tough time in the conversation
swallowing the "some painted/some not" theory. And for me to see on
every case I've cleaned paint being removed, and for some others to NOT
see any paint on their cases, that could really be the ONLY theory, that
could stand up.

OR....more likely, 1. as the cases ARE rough texture, and 2. given Honda
always painted as little as needed.... 3. the cases ARE pourous....and
4...40 years of time and weather simply WORE away any paint that WAS
there.....I would certainly be more of the mindset that they were ALL
painted, and that the folks today who report their cases AREN'T painted,
simply don't know where to look, (the starter motor well) and are
"fooled" by the current appearance of the (aged) rough metal.

In fact, Bob (Hansen) suggested I call Bob Jameson (whom I've spoken to
many times), who was there in Japan when the very first CB750 rolled off
the assy. line. (and spent a lot of time at the Factory)...and would
certainly be intimately familiar with Honda's processes then.

Well...thanks much Chris for your response, and great to hear from you!

Vic


P.S
Steve you told me on phone they other day that you purchased the frame #232 with no motor and then purchased engine #254 from ebay at a later time . So in real life this motor and frame never came together as they original frame and motor from the factory. So how can you be sure of the real history of the engine???

[Steve Swan]

Hi mrhonda2u

Considering Bob H suggested you call Bob J, exactly the point I made in my earlier post.

No one person has 100% of the knowledge or information 100% accurate 100% of the time.

That's why it's so important to share what we know for a more accuarate concensus.

I DID share with you on the phone the other day E254 was acquired off ebay - however - this phone conversation was not with someone named "Vic," as signed in your post.

mrhonda2u, I have NO quarrel with you. No b.s.

Sincerely,

Steve Swan

[mrhonda2u]

Hi Steve I have still have No problems with you what so ever. I will explain why i wanted your phone Number .With SOOC wanting to be a host club at V.M.D this year, Did you ever stop to think that the AMA might be watching our site to see if we meet ther standards??? They just DO NOT throw out invites to Just anyone. They Have high standards with almost 2 millon members worldwide. And with the A.M.A having 10 people on ther board,Who Knows what people they might know and what peopleThose people Might know !!! And remember,when ever (you) post the things you did on our board your name ( the web site's Administrator ) is attached to it. And ther for professionalism is paramount at all times!! Going into the future, I think that the SOOC should alway keep this in mind . Please feel free to give me a call anytime. Kevin Dodge
 
 
 

[Steve Swan]

Kevin,

I agree with your comment on what's posted on the board.

Your point is well taken.

I have no control over people's perception of message content posted on the board. Nor do I have any control when other people post on the board.

What I do have control over is what is written on the board.

And, when what's been written on the board is direct, personal attacks naming any member by name, the names and offensive words are removed.

And, I have been roundly criticized for removing full sentence(s) of details people have posted. Therefore, I have opted to only removing names of parties mentioned. I have updated censored words in the admin area.

I made it very clear in a recent post, direct, personal criticism of anyone is not acceptable and will be removed from this board.

Nothing I have written has been a direct criticism of anyone.

For privacy's sake, you can contact me by email for any further comments you have.

I will assure you, your concerns will be taken into thoughful consideration and discussed with you.

Steve
sandcast232@yahoo.com

[kp]

Vic, Firstly I'm not going to get into a debate about paint or no paint on engine cases because I don't have a clue either way. My dealings with Sandcasts is limited to 3 engines and whilst I've always believed the cases weren't painted, the mere fact that you've probably seen hundreds will no doubt be the clincher with this debate and I will have to rethink how I finish my future engine restorations.

Having said that, there are some areas that will need a bit more discussion, particularly around the alloy used in case production. I don’t profess to be a metallurgist and the science behind the properties of alloys is far more complex than my mind is up to; nevertheless there are some basic facts about alloy properties that are easy enough to source and understood.

Simply, the alloy used in sandcasting is different to that used in pressure die casting. The sandcast alloy is a far more pure alloy and is less prone to oxidation than the pressure die product. Pressure die casting methods have the benefit of being faster, more accurate and suffer less distortion than the sandcast process. However, the process is not without problems. A significant issue is heat transfer, and getting the alloy to flow under pressure throughout the die (or mould) before it cools. Heat is not so much of a factor with sandcasting as they solve the flow problem with temperature. The problems associated with die casting are partly solved by adding other metals such as Zinc and Lead, and probably others as well. The upside is a lighter (read thinner) casting which means less product used but the downside to this is it's prone to oxidation and electrolytic reaction far more than the purer alloy form. In fact the sandcast cases are not so prone to oxidation at all; rather the die cast alternator, chain, valve, clutch and filter covers are the parts that start corroding well before the sandcast engine cases, including head and cylinders. As for die cast cases (post 7414), there was a clear need to paint these as corrosion was/and is a significant issue for longevity. Add to this a polished finish and corrosion became a really BIG problem and this explains why clear coat was applied to all the shinny surfaces. Exposed die cast surfaces are just not durable from an oxidation perspective. Mind you there are alloys that are not as prone to oxidising such as the carb bodies which have a very high zinc content. They are however prone big time to electrolysis.

Assume paint, then as stated in the initial post, the amount of paint used was minimal thus any inherent ability to stave off corrosion would also be minimal. To my mind not painting should not lead to a major corrosion issue, but for originality paint would be the major plus factor for me.
Finally! I have a question. What colour and/or brand paint should I use on engine cases.  KP

[4pots1969]

Hello,
I do not know if I understood everything..Because I did not manage to translate everything..
But I am going to answer all the same has all and to express you my humble opinion...
I am as well convinced as certain engines did not receive a single drop of paint so small where tiny is..
My engine E-1017118 was not painted and no more under the starter..
I made tries with a very powerful scouring agent capable of removing of the epoxy paint and which is now is forbidden has the sale for 2 years (European standards).
Verdict : no paint nobody leaves and she did not disappear even if she was in very fine coat..

And when I hear that it is normal that the paint is completely worn out and disappeared out after 40 years.. there I say that it is necessary to stop moving forward such nonsense which has all those who tell that.. And even if they are the recognized "Gurus" of the Sandcast!!

Nobody can assert holding the truth, but however it would be interesting that some ask themselves questions rather than to smile..
If several members observed this detail it is because he exists..

The real question which it is necessary to put..
Have you already seen this problem on an engine Diecast of 1970?? Where other? And well I think that you will never see him.. And nevertheless it is good the same paint and it also makes more than 40 years.
Even if she wore out has certain place, there remains well 3/4.
I put the powerful scouring agent paint on a block Diecast of 1970 which I had to repaint, the paint after 10 minutes makes puffinesses, her softened and then it withdraws with no problem at all.. But when there has been never of paint.. Difficult to remove him!!

Just a reflection:
Why an engine Diecast has the smooth aspect would hold better the paint than an engine Sandcast has the aspect rugeux and granulated??    

I had bought my paint Alu driving because I had decided to repaint my engine block not knowing how to restore him his original apect aluminum without for it to abimer the typical granulated of Sandcasts.
And now having read this very interesting comment I think that I am going to leave him without paint.
I am going to turn to the process of very low-pressure cleaning of Aérogommage (bicarbonate of soda).
See 2 videos.

For information I saw my own eyes Sandcast E-1014149 and too his engine block was not painted and there we cannot say that the paint was used because it remained stored without running during more than 35 years..

Hopefully you will have understood what I wanted to tell you..

Gérard.G

[Steve Swan]

Very interesting observation.   Thanks for your comments, Gerard.