Painted cases and heads on late Commandos...

Chaps,
Does anyone know why Norton painted the cases and heads on later bikes? Rough cast alloy seems to me to not really need, or benefit from, painting. So why did they?

And, does anyone know what paint was used? It does appear to be very durable stuff.

We have had this discussion here, some time back.
Didn't come to any conclusion to what they used.

A long time dealer employee here mentioned that it was his job, as a junior,
to take a little can of silver frost and paint the cases of all arriving bikes.
It was noticed that the alloy often went a powdery white if left untreated,
and painting it prevented this.
He said he got pretty good at it, if thinned a little it went on easily and was not easily spotted,
and stuck well.

It seems the factory took note of this, and started doing it in production.

It has also been noted that Amal carbs for quite some years came painted in a silver paint
that was very fuel-proof. Related ?
Impossible to obtain now - it was said that the maker wanted an order for 1000 gals,
and no-one would stump up for that much ?

25 years ago I was driving around in a WWII landing craft delivering freight to remote communities. The paint of choice for that old steel boat was full of lead and chromium. The colors stayed bright, the rust was held in check and I didn't have to worry much about having any offspring. Some things cannot be reproduced even through the miracles of modern chemistry. And it might be argued that it is for good reason. It is likely that the original paint may have fallen into that category. This is something to keep in mind when stripping it off as well.

Russ

Fast Eddie said:

Chaps,
Does anyone know why Norton painted the cases and heads on later bikes? Rough cast alloy seems to me to not really need, or benefit from, painting. So why did they?

And, does anyone know what paint was used? It does appear to be very durable stuff.

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It also helps seal any porosity. The inside of my 72 combat trans outer cover was painted on the INSIDE..... :shock: This was the first time I ever ran into the paint issue in 1987...I used methylene chloride stripper to get the gasket off and it bleed down inside the cover and what a shock when I went to wipe it off...

If you closely examine the heads and cases..then chemically strip the paint you will find underneath the paint... the aluminum clean and fresh. Is "later" like my 65 atlas engine or my 1959 88 that had been painted ? Conversely where the paint has flaked off the aluminum has corroded the bare finish has changed from a dulling all the way to a blackish stain.
IMO an overhauled engine that has been blasted and not been painted is not a very good job for a road use engine. After a few years they usually look like crap. Racing engines that get torn down frequently and cleaned for rebuilding or never see rain/water is no big deal.

The paint I use is described here:
http://www.britbike.com/forums/ubbthrea ... Post384804

IMO an overhauled engine that has been blasted and not been painted is not a very good job for a road use engine. After a few years they usually look like crap.

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odd, because seven years ago I had the head off and had it blasted clean and it still looks good now?

I am trying to remember if any of my stock Commando heads came from the factory painted silver, did they?

If they did, someone did a very good job because I could see no evidence of paint used on the heads

in fact the only motor paint I remember was the black first used on the Combat cylinders and then some later?

1up3down said:

IMO an overhauled engine that has been blasted and not been painted is not a very good job for a road use engine. After a few years they usually look like crap.

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odd, because seven years ago I had the head off and had it blasted clean and it still looks good now?

I am trying to remember if any of my stock Commando heads came from the factory painted silver, did they?

If they did, someone did a very good job because I could see no evidence of paint used on the heads

in fact the only motor paint I remember was the black first used on the Combat cylinders and then some later?

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Yes some heads were definitely painted. Mine was one of 'em (1974 RH10).

I chose to go the bare metal route, I had the alloy parts vapour blasted as this closes the pores of the metal better I am led to believe, making it more resiliant to dirt ingress etc. I also ensure copious and regular dowsing with WD40 or AC50 etc. and, to be honest, I don't ride much in bad weather!

But my basic thinking was that if alloy dulls, it can be brought back with scotchbrite etc. whereas I've seen many silver painted engines go yellow or flaky over time.

Hence my question about the Norton paint, you really do have to look close to tell its painted at all, and there are many 40 plus year old painted Cdo engines out there that still look great!

The ability of the original paint jobs to continue to fool norton owners is a testament to the thinness/lightness and good color match of the paint.
Just yesterday prior to my yesterdays posting, I went with methylene chloride stripper to the back of the 1959 88 engine and splashed a bit on then swished the back of the case to release the silver metalic flakes with a stiff artist brush. A swipe with a clean paper towel picked up the silver grayish residue I have evidenced over and over again.

1up3down, where is the wastelands and how much "weather" does you bike see? Here in new england with salt residue on the road in the spring only trailer queens will go unblemished only if you wash them off routinely.
Painted heads/cases with bare patches get corrosion and right next to that is clean paint.

I have a bike that was given to me with blasted head and engine case that has duly suffered weathering. I'll try to add it as soon as I can to the warehouse and get a pix. :twisted:
What you will get in humid environment with no paint:

When did this painting take place 1974 on ?

My '74 MkIIA had painted cases & gearbox shell, but the head...? No traces by the time I got my hands on it, but it had been around the houses a few times :wink:
No paint on the insides of the cases, just the outside, and it came off very easily with modern paint stripper.
Not sure it was done to combat porosity - I think there's some epoxy impregnation process for that, from recollection of my days in the UK automotive industry.
I believe some early Hinckley Triumphs had issues with such things.
No idea what type of paint it was, or what to recommend, but for my 750 silver barrels I'll be using 2K automotive paint. Durability is very good, but can't speak for how the heat will affect the colour as the only ones I've run so far have been black to start with :mrgreen:

I have a head here (RH 10) that is original painted in a very durable silver. Also , I've seen engine cases and gearbox inner covers painted with the silver. A very tough and durable paint that resists stainings. For certain models and years only ?

My (Dec 1973) Mk2a has no paint on either the engine or transmission case or head.
We are talking a stock bore, stock crank, Made in Portugal layshaft bearing bike with original frame paint including the back bone decal.
That includes no silver paint remnants anywhere.

Time Warp said:

My (Dec 1973) Mk2a has no paint on either the engine or transmission case or head.
We are talking a stock bore, stock crank, Made in Portugal layshaft bearing bike with original frame paint including the back bone decal.
That includes no silver paint remnants anywhere.

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Interesting... mine left the factory in September '73

B+Bogus said:

Interesting... mine left the factory in September '73

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Maybe being an export (USA) bike made a difference.
The jewelers eye glass needs to be used for a close up of the surface perhaps, this random picture shows a small patch of something by the timing side.
I very much doubt there is any modern product (silver paint) that would last 40 years on a cylinder head let alone the frontal sections of the cases.

They look awful clean.
What were they cleaned with ??

I've seen that aluminium paint on an aussie delivered Commando,
don't recall if it was an 850 Mk 1 or a Mk 2.

Rohan said:

They look awful clean.
What were they cleaned with ??

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Bunnings wooden handle brass wire brush in medium and soft (wire gauge)