SOHC.co.uk Forums > CB500/550

Were 500 casings originally polished alloy or sprayed with Aluminium paint?

(1/7) > >>

McCabe-Thiele (Ted):
A pretty basic question about the 500 K1 was the engine originally all painted or were the side covers polished?

philward:
From memory they were polished and clear lacquered

Oddjob:
They are painted and then lacquered, if you’ve ever polished a casing you’ll see how much the paint covers all the blemishes and casting marks are under the paint. There are LOADS.

Trigger:
500 K0/K1
Crank cases = painted
Barrels = painted
Head = painted
Sump pan = painted
Oil filter housing = painted
Tacho drive housing = painted
Rocker cover = satin polished and lacquered
Breather cover = satin polished and lacquered
Alternator housing = satin polished and lacquered
Clutch cover =  satin polished and lacquered
Left crank case / front sprocket cover = satin polished and lacquered

Oddjob:
Sorry Graham but you're wrong on this one, the casings are 100% painted and lacquered, Honda are still doing this to this day, there are a few reasons why they do it, firstly, it's cheaper, secondly, the casings are not as good as they appear, they need to disguise the casting marks and the blemishes that they exhibit, painting does that, polishing would actually get rid of a load of them, which shows they ain't polished, thirdly, time, it takes a good amount of time to polish a casing, even if you have the machinery, Honda didn't have the time for that, it would have delayed production and that's something Honda would never have allowed, Fourthly, the consistency, every casing looks the same, you can't get that with polishing, the alloy itself changes with each batch, even if it's only a little, fifthly, if you've ever sanded a casing by hand you can actually see the paint layer, you wouldn't see a polish layer and lastly, the finish is across the casings, into areas where you cannot polish even with really good equipment.

The paint they use is a sort of bright but matt silver, it's the lacquer which gives it the shine. I've never been able to find the colour and I expect it's something that Honda protects as they like secrets.

If you want proof, sand a brand new casing, one that's never been fitted and used. See how many marks are on the surface, there are swirls, injector markings where the alloy was injected and then the excess was cut off, sometimes there are really apparent, sometimes they don't show until you sand them, I've got a grab rail off a VT1100 that you can just make them out and that's after being sanded really flat, there are cavities, where an air bubble sat on the surface, paint fills those in, polishing doesn't.

The major difference between the casings and the crankcases etc are that the latter are unlacquered, the silver is just flat but oddly it's not the same silver as the casings are covered with.

Navigation

[0] Message Index

[#] Next page