Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: AshimotoK0 on September 09, 2015, 09:29:33 AM
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Thought I would start a thread with the finishes on the original CB750 Engine. Please comment. and please add later model finishes if you know them
Crankcases ... Silver painted
Head ... Silver painted
Barrels ... Silver painted.
Clutch cover ... polished then clear coat
Alternator cover .. polished then clear coat
Transmission ('mission') cover ... polished then clear coated
Rocker cover ... polished then clear coated.
Cam chain adjuster housing ... Silver painted.
Oil filter housing ... Silver painted
Breather cover ... Silver painted ?
plus on cycle parts:-
Wheel hubs F & R plus rear sprocket carrier ... polished then clear coated ?
Fork leg sliders ... Polished then clear coated
Brake caliper arm and holder ... Silver painted ?
Brake caliper housing ... Silver painted
Top Yoke ... Black satin painted
R & L bar switches ... black anodized
Front brake M/cyl & cap... Black anodized
Any thoughts on surface prep on the aluminium? The 'Alodine' aircraft style treatment looks the dogs B but pretty nasty stuff as it contains chromic acid and some treatments contain hydrofluoric acid .. again nasty stuff. We don't want to become one of Nurse Julie's patients do we ::)
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Hi Ash, here's my opinion for what it's worth, everything on the engine as you suggest, but I think the smooth breather cover and cam chain tensioner housings had low gloss silver.....which I suspect will just be lacquer over the same paint applied to the rest of the engine.
Cycle parts, as you suggest, but I have never seen unmolested hubs with a true polished finish between the spoke webs....plain cast bright alloy on the rear hub with polishing limited to the outer surface of the spoke webs and the same on the front, no polishing of the centre part of the hub, just the outer webs.....the central portion, as far as I know is bright matt alloy with a thin layer of lacquer over the whole thing.
Wheels that have been 'restored' are usually blindingly obvious because the entire hub gets a mirror polish.
Fork sliders, polished and lacquered, but with that very fine brushed effect that is so hard to replicate.
Brake caliper....silver paint.....not sure about the arm, it looks like barely polished on the top surface and matt elsewhere, possibly just with a coat of thin lacquer, but I'm far from sure.....I doubt they would put any finish at all on the face where the caliper mounts.
It might be an idea to throw some part numbers into Google to see if there are any decent pics out there of NOS parts; failing that, take a look at the SOOC site, the high res pics of an unrestored bike, and the caliper in particular which is photo number 25... even then it's a bit of a guess. Further to that, photo #41 shows the rear hub finish very well
Can you get access to that 500 mile unrestored UK bike....or get someone to take some appropriate pics of it? Failing that, brochure pics or contemporary road test photos might give you a clue.
Just my opinion of course, but I do like anorak detail, so I'm happy to be proved wrong if there is something to learn.
Mick.........kettle738.
PS Are you going to get your switches and M/Cyl black anodised?
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Very hard to get lacquered to stick to a high polished finish, lacquer needs the surface to be keyed the same as paint ;)
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Cheers for that Mick, just the kind of input /feedback I need. I will try and get in touch with Bob Heath who owns the 500 miler plus the Dave Silver Mecum Auction Museum bike only has around 2.5k on it and it was ex-private collection/museum. Bob takes a while to answer emails though. Glad to hear your thoughts about the hub finish as I didn't know what to do about the centres but your observations are in keeping with my 1969 CB350K1 import bike, which was stored indoors and retains all of it's original finishes. It too has clear lacquered finish hubs , semi polished on the faces but unpolished on the inner 'ribbed' section. Do you reckon that the crankcase lower half was painted, I suspect it was but turns out that the CB350K1 I have had silver painted upper/bare aluminium semi-polished finish as original.
Agreed on the brush alloy finish on the fork sliders, I have warmed to blingy chrome but I hate highly polished alloy on 60's/early 70's Hondas ...it just doesn't look right. How about the tappet caps .. what do you reckon on those?
I agree this is all anoraky and there will be many on here who think our obsession is a form of madness but It's a hobby for me that keeps me sane in a weird sort of way.
Unsure on the black anodized finish, may just paint them using the 'Wyatt' method.
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Very hard to get lacquered to stick to a high polished finish, lacquer needs the surface to be keyed the same as paint ;)
You need very nasty chemical treatments to do that Graham ... like Vic World uses.
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Ash - when you come down to mine I can show you two very original unmolested K0's that retain the factory finish everywhere. If I get a chance before then I'll pull them out and do some macro shots of the areas outlined above. James.
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My Black Bomber had just the top crankcase painted......ditto my GT750 Suzuki.
The CB750 is painted upper and lower cases........but the sump pan is plain un painted bright alloy.
Best thing would be to have a good trawl round James' un restored examples.
Mick............kettle738
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Unsure on the black anodized finish, may just paint them using the 'Wyatt' method.
Gave RGP750 some paint to do the master cylinder, he was very pleased with the results. Have been using this paint for a few years now and found it very good.
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Extended the title to plus 500/4
Anyone have a list of the engine finishes for the CB500. I am primarily concerned with the '71 K0 but any advice on all models will be useful.
Anyone know the finish on the CB400F & CB500 alternator cover plate ?
Cheers
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Hi,
Back in the man cave after too much pud,
I have some new old stock tappet caps for 400/4 which are polished and lacquered. Also nos fork sliders for 400/4 again polished and lacquered, but as said before quite difficult to replicate. Most polishers go ott and remove the roughish casting marks around the mudguard bridge and axle hole, these are definitely visible on nos.
I did a page on my site about polishing the legs on my GB 400TT and these are similar to the 400/4.
It's part 2 of the GB 400 stuff and the web site is under the avatar.
Hubs, definitely only polished on outer flanges, rest as cast, then lacquered all over.
Ian
Oops, the 400/4 alternator cover plate (the finisher with Honda stamped on) is clear anodised and satin black detail with clear lacquer over the whole lot.
The alternator stator mount cover is polished and lacquered (both nos)
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Just to add to the pot. A Dutch guy on the HondaTwins site added this to one of the posts on alloy finish and he may well be correct.
These are his words not mine:
"For years I tried to restore the original surface finish of the CB72/77 heads. In 2005 I got a NOS head, boxed and in plastic. The surface finish was a zinc layer. This zinc layer is formed during the casting process. The picture shows the original finish, being zinc. This zinc will vanish during the years and the cylinder and head turns dull. It's difficult to restore the zinc layer".
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I've got to say that I had not thought of a thin coat of silver under the lacquer - makes a lot of sense though and is why we can't really replicate it after polishing. As we know, it wasn't that good really and if you rode on salt laden roads just once and didn't rinse it down, then that familiar mottled effect developed by the following day.
As a complete philistine, I have frequently paint stripped NOS parts to remove the lacquer (and now seemingly this silver base coat) preferring just a polished and waxed finish which I find much easier to keep clean. I wonder if anyone knows what silver base was used and if it would still look correct under a more durable 2 pack lacquer.
You've opened a can of worms here Ash - do you know how many flakes of metal per square inch there should be in the paint on my tank?
Ian
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So why not simply use Alodine 1001 on the now coat-less, polished aluminium surfaces before clear coating them?
http://na.henkel-adhesives.com/product-search-1554.htm?nodeid=8797999529985
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So why not simply use Alodine 1001 on the now coat-less, polished aluminium surfaces before clear coating them?
http://na.henkel-adhesives.com/product-search-1554.htm?nodeid=8797999529985
Considered it but hard to get hold of in the UK , very expensive and VERY toxic, possibly a carcinogen. Surprisingly though the safety data sheet on the dip you use to passivate zinc plate (very cheap from Gateros plating) states it contains Chromic acid and Hydroflouric acids! I know for a fact that the aerospace industry used Chromate dip to promote adhesion as I think does Vic World the CB750 sandcast guru in the States on the likes of alloy fork sliders etc.
http://gaterosplating.co.uk/Replacement-Items.php
Scroll down to this:-
[attachimg=1]
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Evidently Vic World gave a talk on finishes etc in 2009 in Ohio to the SOOC boys but sadly nobody videoed it (well not to my knowledge). Bet the 'acid' mentioned in the article pic below was Chromic acid.
[attachimg=1]
WILL INVESTIGATE THE GATEROS SAFETY DATASHEETS . possibly the blue passivate may do the trick. Dunno...will report back .
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Considered it but hard to get hold of in the UK , very expensive and VERY toxic, possibly a carcinogen.
Alodine 1132 would be a rinse free solution, so no toxic waste water to be worried about.
But we've some hobby pilots and hangar crews around, I'll stretch my feelers to check what their using.
http://gaterosplating.co.uk/Replacement-Items.php
Black passivate, enough to make 5 litres of passivate £24.99
The black passivate sounds interesting, always wondered how that's done.
Fine for a number of brackets around bikes, MCs, switch housings or those carb rubber clips.
Question on the Cloud Silver Metallic spray engine colour from this source: http://www.rsbikepaint.com/en-gb/shop-paints.php?colourscheme=13724&30077=on
- how close is it to the original Honda engine paint? (will it stand out as "fake" or "acceptable" to a knowing person?)
- does it really require the lacquer coat as suggested on the shopping cart?
- will the paint require curing in an oven, or could that be done on the engine by letting it warm up?
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Don't think the black passivate is any good for alloy only steel (like carb clips, fork top yoke D spacers etc). For M/Cyl , switch bodies i think you need anodizing or PJ1 Satin Black baked on in an oven then given a quick buff with Solvol.
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For M/Cyl , switch bodies i think you need anodizing or PJ1 Satin Black baked on in an oven...
hmm, is that PJ1 paint resistant against brake fluid?
Currently my friend is struggling with some (expensive) BF-resistive 2-K paint for the M/C on his z750... quite a hustle it seems... (as he did not listen to me to wait for my soda blaster to arrive first... would have provided the clean, nice surface required for an easy application with durable result...)
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For M/Cyl , switch bodies i think you need anodizing or PJ1 Satin Black baked on in an oven...
hmm, is that PJ1 paint resistant against brake fluid?
Currently my friend is struggling with some (expensive) BF-resistive 2-K paint for the M/C on his z750... quite a hustle it seems... (as he did not listen to me to wait for my soda blaster to arrive first... would have provided the clean, nice surface required for an easy application with durable result...)
Not saying it's BF resistant totally but it's what a top CB750 restorer uses and who wrote the definitive book on the CB750. If you are careful anyway, you can avoid getting BF on the M/Cyl. You can remove the old anodizing using caustic soda on switches.
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So why not simply use Alodine 1001 on the now coat-less, polished aluminium surfaces before clear coating them?
http://na.henkel-adhesives.com/product-search-1554.htm?nodeid=8797999529985
Found this languishing on someone's shelf during today's travels and 'stole' it . For Christ's sake don't Google it. main ingredient of 'Alodine'
[attachimg=1]