Black engine finish

[byron]

I would like to black paint these vapour blasted barrels prior to assembly and was wondering if anyone has any good experiences of suitable paints which are heat resist and petrol and oil resist. Thanks and advance
It almost seems a shame to paint something so nice and clean!!!!!

 

[solidstate100]

I have painted a small number of barrels and cylinders etc back in the day. The main problem wasnt so much what paint, it was getting decent coverage in the depths/sides of the fins wihtout overpainting the exterior surfaces etc. Decent surface prep with any decent heat resistant paint will do it, but to be honest I cant really see why you would paint those barrels (IMHO of course).

Ultimatley after a short period I always wished I hadnt painted them.......

 

[dr nosh]

Byron.

1. Don't paint them.

2. If you have to, then I used VHT primer first. Applied paint by brush 'down' the fins, and whilst wet, sprayed over, but as said above don't over cover the outer edges of the fins. Did the same with VHT Satin Black to finish. 2 coats.

 

[dubster]

Why's everyone advising not to paint?

 

[Kenny]

Pots on an airhead are notorious for collecting dirt...they'd look rubbish after a few rides out..and a right bugger to clean. May even devalue your bike.

Just my 2d worth

 

[sparky56]

Have you considered ceramic coating? <a href="http://www.camcoat.com/main/coatings13.html" target="_blank">Linky</a>

If I read it correctly it's £40 for two cylinders.

 

[Skid06]

as above, ceramic coating try camcoat, just used them to paint some headers

http://www.camcoat.com/

 

[B Murr]

Is anodizing an option?

 

[solidstate100]

Is anodizing an option?

Im guessing that ALL the surfaces would end coated if you anodize, ie sealing surfaces bores etc which could be a problem. That said I am well out of touch with surface coatings these days so could be well off......

 

[Beemerboff]

According to people in a position to know there is a fine line when coating engine parts between improving the cooling, as black radiates heat better than silver, and applying too thick a coat which impairs heat transmission.
Powdercoat is usually too thick and impairs cooling.
Ceramic coatings are probably worse in this case too - they are commonly applied to auto exhaust manifolds and headers for this very reason.
Engine coatings are usually a cost saving measure, according to Phil Irvine the Vincent motors were only painted black after they released it was taking longer to fettle and polish them than it was to machine them!

 

[Andy B]

All the barrels on a modern boxer are painted or part painted so how do they do it? Whilst I've seen flaking paint on the front of engines I've not seen it on the barrels.

 

[chrisshrops]

as above, ceramic coating try camcoat, just used them to paint some headers

http://www.camcoat.com/

How did they come out ?i have some rusty lanfranconis I may have blasted and coated

 

[Beemerboff]

Looks like Camcoat have a thermal dispersant product for auto cylinder heads, which could be the go for barrels if it has UV resistance.
The site also confirms that ceramic is not he way to go if you want heat dispersion, and you probably do from barrels - these fins are there for a reason.

 

[Rob Farmer]

The barrels aren't such an issue to paint but soon get stone chipped. It's the cylinder heads that are a problem. The variations in temperature round the head make it hard to find something that will adhere for any length of time.

I shot a few pictures of my airhead engines with a thermal imaging camera. This should give you an idea of what your up against. Don't pay any attention to the displayed temperature. That's a powder coated rocker box, you can see how much heat it's holding in.

 

[byron]

That is an amazing photo Rob and gives a clear indication of how hot some parts really do get. I only want to paint the barrels and decided to buy Halfords super high temperature paint to see how it goes.
Thanks again for your help chaps

 

[Beemerboff]

Rob, my rocker box gets cooled by the oil inside it , if yours doesnt you have a big problem coming up.
Do you have an image of a uncoated box for comparison, IMHO one image doesn't tell you anything unless you have something to compare it with.

 

[Rob Farmer]

That's engines done 220,000 miles I'm sure if there was an issue I'd have known by now .
I'm not suggesting that powder coating is a bad idea just trying to show the differences in temperatures around the engines.

This is my pd engine for comparison - standard rocker boxes with no powder