painted engines

I'm thinking of painting my engine flat black. I plan on using header paint in a rattle can. Will this cause overheating problems. Can anyone who has done this post pics, product used, how long you've had it and how its held up.

I painted mine semi-gloss black using the commonly available engine enamel from the parts store (Duplicolor Rattlecan). Cleaned, sandblasted, cleaned again with acetone, then primered and painted. No overheating issues at all, even in Texas summer heat. Mine has been together for about a year and a half now, and is holding up well. The main thing is getting your cases really clean. Any dirt or oil will prevent proper adhesion.

Not sure about using header paint. I did my header with header paint, and it definantly has a different quality to it. Honestly my header will need a touch-up within the next year.

Painting the engine black can reduce temps by up to 50 degrees.
I use PJ1 satin and bake it on in the oven.
It's very close to the original kwak black but i do start with freshly blasted and de-greased castings for a durable finish.

Long ago I read where Honda first started painting their roadrace engines flat black in order to help their engines dissapate heat. They used flat black instead of a paint that had a "shine" to it because the flat black was "rougher" in texture which gave it more surface area for heat to escape. Anything that had a sheen was smoother and so didn't have all the surface area beings it was level compared to the roughness of a flat-based paint. You don't want to put the paint on thick as it will hold in heat also. That's why chrome, although it looks good, is not good for the motor as it will hold in heat also. The thick paint makes it harder for the heat in the engine to escape so the engine keeps the heat inside which isn't good. Thick paint acts like insulation to keep the heat in and harder for it to work its way out.

Don't know if you get it over there (but pretty sure you do) is heat dispersing black paint comes in satin or matt, might be the same as header paint though not sure.

The main reason why flat black is better is that anything with a shine is reflective. And in radiation heat transfer, the ability of a surface to emit heat, or emissivity, is generally lower the more reflective a surface is. So the flatter you make it, the better it will emit heat. The surface area comes into play as well of course.

I plan to use flat black header paint on the engine, because, while engine enamel is fine for water cooled engines, an air cooled engine probably gets slightly hotter than the roughly 500 degrees that most engine paints are rated at, while header paint is rated to handle upwards of 1600 degrees. I am a body man, so paint prep is second nature. The headers I actually plan on painting flat black as well, and wrapping. I appreciate the input guys. Next up, deciding what to do about these ugly Chrome fenders. I'm thinking about a newer style rear fender, as I plan on running rather large bags. Something like a newer shadow or Vulcan.

Never understood the hate on chrome fenders. :silly:

I may be wrong but I doubt these motors run even close to 500*

I could definitely be wrong on the numbers, but obscene yet to find flat black engine enamel anyway, and the header paint is strictly flat. It may have some hot spots though, plus the exhaust passes millimeters away from the engine in spots, plus the exhaust coming out of the head. I'd rather spend the extra 50 cents and not have to do it again

I found most unite colors for engine at Eastwood's online store.They have an idiosyncratic enamels for all kinds of engines.

As noted by several above, a flat black surface will emit more heat that the stock aluminum without paint. I don't know about these air cooled engines seeing 500 degree external temps either, so I can't see any reason why header paint shouldn't work, and probably work quite well.

As to overall engine temp, painted or not, keeping the engine and cooling surfaces clean, and free of grime/oil/road dust etc... is likely to be a far more significant contributor. It doesn't take very much dirt to make the difference between painted or not painted nearly irrelevant.

I'm not implying that anyone here doesn't keep everything ultra shiny all the time, but there you have it. Its copping some paint manufacturers slogan, but a clean engine is a cool engine. :laugh: