Bicycle motor coloring?

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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A couple of things lately brought me to post this.

Six of the bicycle motors I have or have had, had a natural finish on them. One has paint....I didn't figure that out until I was cleaning it.:crash:

I clean all bicycle motors prior to giving them the once over for a couple of reasons...one is it's a lot nicer to work on an engine thats not covered in some funky Chinesemoline that smells almost as bad as the cheap grips that come with some of these kits. Another is if you don't clean them, that stuff bakes on to various degrees and looks like **** after a short time.

Polishing them is labor intensive and a specific look, enjoy!

Painting them is easy, and uses no special paint. Just be sure to clean the bicycle motor thoroughly with a strong solvent first. You don't need high temp. paint! I have painted with "regular" Krylon with exellent results. The only place the paint won't hold up is the first 6" of the exhaust, it will turn a funky grey. Most of the time you'll leave the pipe chrome anyhow. Clean the engine, and spray with your favorite aluminum paint for a refined look. Black for the vintage 70's look, or color match the engine to the bike if you went to art school. (camo doesn't count, see second picture;) )

Finally, a nice charcol finish can be made using oven cleaner....follow the directions, or better yet, apply, wait a half hour, rinse THOROGHLY.

See the engine in the middle for an example of a "darkened" motor, still not cleaned up for mounting, but you get the idea.
 

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jasonh

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Jun 23, 2008
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Eventually I'd like to get around to painting my motor. I have a few ideas, will just have to wait and see. Won't do it till I get a new frame though. Not sure if the current frame is worth cleaning up, since it's bent a bit.
 

azbill

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May 18, 2008
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I used an old paintbrush and thinner before i painted mine
(I ran it for 60m before I did it, to make sure it ran well)
I like the 'darkened' look, does the oven cleaner only affect the aluminum like that or all it touches???
 

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Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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It only affects the aluminum, and the longer you leave it on, the darker it gets up to a point. It doesn't hurt the aluiminum or eat it away at all, just darkens it. It does take a bit to get all the residue off, but nothing out of hand.

There is still some residue on the engine in the picture, but I didn't scrub it completely, just rinsed it so it would stop darkening.

It goes without saying- don't get any inside the ports.
 
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jasonh

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How is painting the fins going to help? Really if anything it will hurt cooling. You could use radiator paint though, and that should have little impact.
 

HT60CC

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I'd been led to believe that the colour black is a good radiator of heat, thus would radiate more heat from the engine. I was probably misinformed. Nevertheless it would make oil seepage from gaskets ETC.
 

jasonh

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Jun 23, 2008
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Yes a black car in the sun will get hotter than a white car, but any kind of paint on aluminum fins will hinder the cooling ability, as it "blocks" the air somewhat from the fins.

Now, using the oven cleaner method would work, as it doesn't paint the aluminum, it just causes it to oxidize and discolor, but you still have raw aluminum.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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Yesh, yesh you do.

I have read that flat black paint helps disipate heat quicker....didn't retain why. I know it's used on a lot of engines.
 

jasonh

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I just don't think paint will aid in cooling. Aluminum is able to transfer heat much better than any paint would be able to.

You're cooling by passing airflow over the hot aluminum fins. The great ability of aluminum to transfer heat would be hinder by covering it up with something. Just like wearing long sleeves on a hot day. You're not going to cool off nearly as well as if you had short sleeves on. Or heck, just paint your arms and see what happens.

If you want to color the motor and not hinder the cooling capacity, you could go the oven cleaner route, or try anodizing the aluminum. That would actually be interesting. I read a while ago how to anodize aluminum yourself at home. Might be fun. My wife would probably try to kill me for it though.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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You could always say "I'm cleaning my engine honey, I need the EZ-Off." Then when you spray it all off, just say; "Uh, Oh, look at that!, I guess I'll haveto live with the black engine now...
 

jasonh

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doing that would be no issue. I was referring to the DIY anodizing :)

Just think, I could transfer the motor to my blue bike and have the motor and all parts be colored blue as well. Or some other cool color.
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
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up north now
I call rattle can paint jobs "Hillbilly anodizing". I just hook up the battery charger and clamp the pos. on the bike and the neg. on the can of paint and....
 

eDJ

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Jul 8, 2008
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I used to be of the school of bare metal discipated heat better than painted metal. I was around some engineers who worked with refrigeration equippment
and got into a discussion with them about this very thing.

They were explaining the merits of painted metal giving up heat much better than bare metal. I've noticed since my 500cc motorcycle has a painted black
cylinder and the motor painted with clear coat.

The engineers were explaining the reasons they paint much of the air conditioning equippment they built in their factory as with the refrigerators etc.

Anodizing which is basically dying aluminum isn't difficult. I first learned how to do it with a book titled, "Formulas Methods Tips & Data". I want to look into Jasonh's link and see what it says about anodizing.
 

jasonh

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Jun 23, 2008
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yep, it is. But you can also color it while you're at it :) But I'm not saying it helps heat transfer any.

eDJ, I wish I could've gotten in that conversation, since that goes against pretty much everything I've learned. I'll have to bust out some google-fu today and see what I can come up wiht.
 

Norman

LORD VADER Moderator
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Jan 16, 2008
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painting your engine will not hurt it. I like the bare metal myself eaiser to see if its leaking where it shouldn't be. But for you guys and gals that want to paint it go for it.
Norman