pros and cons of painting engines

[Mista M]

black absorbs heat first, but it also dissipates heat the quickest on the color spectrum if you want to get all scientific.

[Agemax]

get the engine vapour blasted and leave it bare aluminium. no problems with heat dissipation,flakey paint or oxidization.job done

[tkent02]

Absorbing heat isn't in play here, engines get them selves hot. Is the increase in dissipation due to being black more than the increase in insulation from the added paint? I think it just doesn't matter. Paint it if you like the look. I like it, I paint some of them, they don't get any hotter than the others as far as I can tell. Too hot? Not gonna happen.

[Griffyn]

The black/absorbing thing is fact, except it doesn't work that way here. Why? Because heat ALWAYS travels from hot to cold. And since the temperature of the engine is higher than the heat from the Sun, the black paint will actually move heat from the engine to atmosphere. Really.

This is the truth. All the good air-cooled VW mechanics know that chrome engine tins will make the car overheat. Black is the way to go and nothing else will do unless you're doing a full custom car or a buggie with the exposed engine and extra oil cooler and all that jazz. Then it usually overheats because of people running the valves tight and the carbs lean no matter what color the tins are.
And all of my physicist friends tell me that the science backs me up on that.

As for the original topic, my advice is to prep, prep, prep. If your engine looks dirty and oxidized and it's just too much work to polish it up, then it's not clean enough for paint and you should just run the bike dirty until it dies under you. Paint is easier to keep clean over time, but you need the engine a lot cleaner to paint it than you do to polish it. Unless you've already had the motor blasted and steamed and all that jazz, in which case 'Good show. Do as thou wilt upon thy own lands.'

[FLHGSRay]

I think it just doesn't matter.

I'm with this guy. Even though the science supports black dissapates heat better, I'd guess the difference is minimal. A few degrees at most.

[tkent02]

If your engine looks dirty and oxidized and it's just too much work to polish it up, then it's not clean enough for paint and you should just run the bike dirty until it dies under you.

Heres a bit of news. Dirt on an engine won't make it die. Ever.

[Old guy]

Paint it. Touch it up with rustoleum paint pen. I don't have the patience to polish.

[Griffyn]

Heres a bit of news. Dirt on an engine won't make it die. Ever.

Never said it would. Don't even know where you'd get the idea that I suggested it from what I wrote.
I just said that if it's too much trouble to polish, run it dirty until it wears out.

[Rob S.]

Me old too. Touch up the headers frequently - spray it on cardboard, then apply it with a brush.

[tkent02]

My bikes don't die, I maintain them.

[Griffyn]

My bikes don't die, I maintain them.

Wasn't talking to you when I said it then, was I?
Seriously, are you going to try and add to the conversation or just challenge for the world's worst semantic trolling job ever?

So yeah, paint or not to paint is an individual preference. Done right it neither helps nor hurts the cooling by more than sub-functional degrees. Do it wrong and you will uncover a world of aesthetic problems, mostly in chipping, peeling, flaking and looking like crap. Your bike, have fun with it.

[Gorminrider]

Even with the best prep

Anything you paint has to be repainted, someday. Ask anyone with a house, a boat a car and yes, even a motorcycle. Ask SuzuKi. They put a good varnish on the engine originally and what happened?-right.
So the first time you do it it'll look great for as long as it takes for the first stone to chip it, the first edge to lift a bit and let some water in...so it goes. But good prep helps a lot (7 years sounds darn good to me! http://www.thegsresources.com/_forum...10&postcount=3)
But bare metal needs maintenance too. There's no rest for a perfectionist.

[tkent02]

Wasn't talking to you when I said it then, was I?
Seriously, are you going to try and add to the conversation or just challenge for the world's worst semantic trolling job ever?

I already added plenty to it. Paint it or don't paint it. Whichever you want.

[Rob S.]

I just ordered some glossy black engine paint - good to 550 f, my exhaust is flat black good to 2000 f. The engine paint's half the price of the exhaust.

[GSX1000E]

I use VHT Hi-Temp Caliper paint of my engines. It is rated to 900 degrees Fahrenheit and costs no more than the inferior Hi-Temp Engine paint that is only rated to 500 or 550 degrees. The choice is yours as to which one to use.