Honda CB750 Sandcast
The Restoration Shop => Engine - Cosmetic Only => Topic started by: vnz00 on October 31, 2011, 06:02:05 am
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Hi Guys,
Just painting my engine prior to assembly.
I have painted my cases, matching the colour to the inside of the starter motor recess. It is really quite bright- only slightly less shiny than vapor blasted aluminium.
Couple of questions:
Is the oil pan also painted, or is it natural cast finish. I'm guessing natural.
The oil filter cover (die cast, finned, no inner supports), I'm guessing isn't painted.
Head and barrels- are these a slightly darker silver than the cases?
Cam chain tensioner housing - I don't believe this is painted.
Grey epoxy sealant near oil line bosses- not painted?
Thanks guys!
Steven.
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Steven
Mark B's restoration thread over at SOHC4 should answer almost all of your questions. I'm using it as my bible!
http://forums.sohc4.net/index.php?topic=64283.0 (http://forums.sohc4.net/index.php?topic=64283.0)
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Wayne,
I'm flattered by your loyalty.
Steven,
Those were conclusions that came about from observations on the bikes I have and reading as much as I could. Others may have other opinions. But to summarize what I think is correct, the cases, finned oil filter cover, cam chain tension housing, cylinders and head and breather cover all painted the same color. The oil pan, no paint. I also believe the smooth oil filter cover had the same finish as the other polished (brushed) covers. As far as the grey epoxy (I always thought is was something like JB Weld to repair flaws in that area and other areas too) I just painted over it. Anyone else have opinions I would like to hear them too. I'll be painting the same parts on #97 soon.
Mark
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My two cents worth, all the breather covers i've seen clearly have a gloss painted finish, silvery grey color, which appears (to me) very different than the aluminum color on cases. The broken set of sandcast cases (accompanying 232) came with early engine parts (including sandcast cam chain tensioner and a painted gloss silver grey breather cover.) The sandcast cam tensioner appears to have an aluminum finish covering the metal, appearing same as cases. The one early finned oil cover I've seen, with no internal webbing, *appeared* to have a painted surface, the coating of the paint was thick, not as bright aluminum color, compared to the thin painted coating seen on the cases. I'm not sure what to say about the head and the cylinder block. My personal belief on early heads/cyls, based on not having the best early examples to look at, these parts were painted same as cases, but i would hazard to say there was possibly a thicker layer of paint on the upper surface of top fin of head, next to the cam cover. Later (not sandcast, perhaps later K0 and certainly K1) heads/cyls, my observation,used another type of coating, a very thick coating that seemed "rubberized," would peel, could actually pull off, "stretchy," in consistency and when subjected to high pressure cold be peeled off in loose areas, half to 1 inch at a time. I'm also going to hazard the guess, as production numbers advanced, the finishes used on these engines was also a more refined and automated process. What i am saying, is the early and very early bikes engine finishes may have been applied differently, using different application methods and materials, compared to later bikes, even perhaps, the later sandcasts.... Deciding what an original engine finish may have looked like for a particular Evin range, particularly in early production might be a challenge to say, finishes were "exactly" like this.....? I would not be surprised to hear varying observations.
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Hi Guys, thanks for the responses. Now I have had a closer look, I thought I'd chime in with what I found and ended up doing.
Head, barrel and engine cases all appeared to be painted the bright aluminum color. I observed and color tested a patch, and bright alu is what it is (almost as bright as fresh cast alu color).
The oil pan I noticed wasn't painted- I had it vapor blasted and it is an as cast aluminum look.
The finned, non-internally ribbed oil filter cover is definitely painted. It is however a matt finish aluminum color. I also noticed (also on a 2nd similar cover I have from another sandcast) that the sides of the oil filter cover appear to have been linished after being painted. Subsequently the sides are polished bare alu where the finishing was done with some residue of paint in recesses. I'm curious if anyone else can confirm?
The breather cover and cam chain tensioner housing are a gloss finish alu color. I.e. Same shade as the oil filter cover but a gloss finish. Strange but true. My tens housing was diecast however, not sc as per steves. I have a NOS tensioner housing which is as cast and not painted, so maybe later housings were not painted.
The front brake caliper and arm appear to be a similar colour matt finish alu to the oil filter housing. It's original color you can see clearly on the arm once you remove the caliper.
So I will say that most of my observations coincide with Steve Swan. I managed to find 3 matching silver paints, so I'll post pics of b4 and after one day soon.
I was blown away by how bright the alu color is on the cases as it seems the only place which still had some color was in the starter motor recess. Defn painted however, and the color I used matched what I found.
Welcome any comment for/opposed to my findings here. Oh and BTW, I left the epoxy plugs unpainted ;)
Thanks,
Steven V.
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After my last post I looked at my finned oil filter cover and breather cover and I'm tending to agree with Steve and Steven. I would be interested in knowing what the paint spec is. For now I have only painted the cases, cylinders and head the aluminum color.
Mark
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Steven, i'm glad you brought up that linished finish on the sides of the finned o.f. cover. i have seen that bare aluminum on the sides of these covers.
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I haven't seen that term before, what is linished?
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Per Wikipedia - Linish is an engineering term that refers to the process of using grinding or belt sanding techniques to improve the flatness of a surface. The flatness may be two-dimensional, i.e. with the view of achieving a flat plate, or one-dimensional, e.g. with the view of achieving a perfectly cylindrical shape. The machine that does this may be called a linisher or a linish grinder. The technique may also be used, with finer grades of grindstone or sanding belt, to polish a surface.
Could not find the word in the dictionary.
I believe linishing is an older machine operation, from the turn of the 1900's or even earlier. My good friend, who was a machinist and motorcycle man from the 20's through the 80's used that term.
Would be good to hear Keith's thoughts on the term linishing.
In any event, after reading Steven's post, i DO remember seeing what appeared to be factory created sanding/grinding markings on some of those o.f. filter covers. (and thinking to myself, "That's odd.")
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Linishing is a commonly used term here in Oz, at least by us old farts ;D
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Honest to God, I have never heard the term before and I have been a machinist and/or in the machining business since 1974. Learn something new every day! I guess we have always used more specific terms such as grinding, lapping, and polishing. We do use belt sanders from time to time for loose tolerance deburring or cleaning of rough parts. Don't normally deal much with the latter. Most of our parts are very complex, high precision, exotic material stuff.
About the oil pan. I think I have 3 versions of SC oil pans - as cast, clear coated, and painted. Pretty sure all of them are stock Honda stuff. Would have to dig them out to be sure but I think I recall 1 NOS, as cast, and 1 NOS, clear coated. A couple of my unrestored SC's appear to have painted pans.
Keith
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There are at least 2 different casting of K0 oil pans. One has a casting square on the underside middle where original sandcast seem not to have this casting feature. I have an unpainted and also have seen the clear painted type
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Honest to God, I have never heard the term before and I have been a machinist and/or in the machining business since 1974.
I've been a an engineer for about the same time and a machinist before that too. Thanks Keith, I'm glad I'm not the only one who hadn't heard that term.
So does anyone have any idea what VIN's had unpainted pans? My #97 sure looks to be unpainted but it was so crusty it's hard to know for sure.
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I've not seen a pan with a coating.
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I presume KPis observations were actually about sandcast rather than K0 pans, and if so I agree in full.
As to "linishing" - a common term here in the Uk. In fact at work we have a "linisher", this being a floor mounted continuous abrasive belt machine used for clean up on flat metal surfaces, taking burrs off edges / corners, etc.
cheers - Chris R.
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I presume KPis observations were actually about sandcast rather than K0 pans, and if so I agree in full.
As to "linishing" - a common term here in the Uk. In fact at work we have a "linisher", this being a floor mounted continuous abrasive belt machine used for clean up on flat metal surfaces, taking burrs off edges / corners, etc.
cheers - Chris R.
Yep, correct Chris. I should have said sandcast. As for the clear painted oil pan I saw, this item was on eBay so could have been clear coated by the seller
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Hi folks, Thanks for all the discussion! Great that we have it all here for future reference.
Yes linishing is a common term here, especially for a light clean up of crank journals. They are not machine cut, but retrued back to a flat surface by linishing. It just removes light wear marks. In reference to removing casting flash, the belt sander Chris described would be used. I couldnt see it being polished off with a mop and compound, and a disc sander wouldn't have enough 'give' and would result in flattened edges on the rounded cover.
Well painting again on the weekend, hope to get some finished pics up there..,
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My two cents worth, all the breather covers i've seen clearly have a gloss painted finish, silvery grey color, which appears (to me) very different than the aluminum color on cases.
Sorry to dredge up an old post but are you saying that the color is lighter or darker than the cases? Anyone have a paint spec for a close match?
Mark
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Mark, slightly darker gloss finish to the engine cases which are a bright alu finish.
Ill post a pic of what I painted mine which I colour matched to original.
I believe the cam chain tensioner housing is the same colour.
Regards,
Steven.
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This is the finish of a NOS sandcast cylinder head breather cover (12321-300-010), it was in an original Honda closed package. I think that the cam chain tensioner has the same finish.
Marcello
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Thanks for the feedback guys. However, it's really hard from the photos to tell the shade.
Steven, just to make sure, you are saying the breather cap is lighter/brighter than the cases? I have several caps that are different (lighter and darker). I guess the key thing here is what was the color on early covers. I've been holding off on painting the cover (and the cam chain tensioner too) until I could sort this out. I have to dig out my caps this week. I hope I have the #97 cap labeled.
I'll have to take a closer look at my cam chain tensioner too. I always thought they matched the cases. I'm not doubting anyone's observation but it does seems odd to me that Honda would have two different colors for engine parts although it would make more sense that the breather cap was different.
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Hi Mark, sorry I didn't word my response very well:
The breather cover and cam tensioner housing are a slightly darker silver, gloss finish, to the rest of the engine which is a bright alu finish.
Ill post pics of 1853 which is what I used as my reference later.
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Hi Mark, sorry I didn't word my response very well:
The breather cover and cam tensioner housing are a slightly darker silver, gloss finish, to the rest of the engine which is a bright alu finish.
Ill post pics of 1853 which is what I used as my reference later.
Agreed with Steven. The cam cover breather covers i've seen that came with engines, clearly appear to have a painted finish. Light grey. Not silver or aluminum. Finish is not a high gloss, but certainly every bit of a semi-gloss+. imho, one cannot use a later production part as an example of what one would think the finish or appearance would have looked like on a part used on the assembly line.
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Dear Steve, I agree that a late production part cannot be used as an example, but the NOS head breather cover (12321-300-010) above was superceded by (12321-300-020) after serial number 10.338, an non longer produced from October 1969. Couldn’t a glossy paint from 1969 become a semi glossy at 2014?
Marcello
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Dear Steve, I agree that a late production part cannot be used as an example, but the NOS head breather cover (12321-300-010) above was superceded by (12321-300-020) after serial number 10.338, an non longer produced from October 1969. Couldn’t a glossy paint from 1969 become a semi glossy at 2014?
Marcello
Hi Marcello, So i understand what you are saying... :)
1. That new breather cover is high gloss finish?
2. After 45 years, gloss finish degrades to semi-gloss ?
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Steve, my NOS cam breather cover has a gloss finish, more a clearcoat with a little bit of silver paint.
I supose that due the time and usage a gloss part from a 69 bike today has today a semi-gloss finish.
Marcello
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Yes Marcello, i suspect you are correct.