So I continue to make progress with my 65 Revive project and have come to the point where I need to address the finer finishing details. The engine has been disassembled, cleaned, inspected, and parts have been ordered. Before the reassembly can take place the external engine components need to get color on them.

The plan from the beginning was to powder coat all the visible engine components. The difficulty comes in deciding what color, and textures, to use to finish the engine with. Everyone has fairly specific taste when it comes to the details therefore I decided to follow my wants.

I know that I do not want anything “showy” or flashy. I want to maintain a raw, natural, mechanical look to the bike. I want to maintain the look of a “machine” so I decided to keep the color palette in line with an industrial and stock look. Those colors being blacks, silvers, and greys.

So once I decided what the basic colors were going to be it was time to start browsing all the powders available in the color line up I wanted. Unfortunately it is somewhat difficult to get a good feel for the colors just by viewing a jpeg on the computer. Since the color scheme was too important for me to screw it up I figured the only way I was going to figure things out is if I started to spray some samples.

3 sample EGRs blasted, cleaned and ready for coating.

So I ended up ordering 13 different powders from 3 different companies. I then got my grubby hands on some old automotive EGR valves that would serve as my sample test pieces. I chose the EGR valves because the aluminum finish was similar to that of the bike, plus they had some corners and curves that would allow me to practice coating, and they were free. The valves were fairly carboned up so after I stripped the electrical drives off them I gave them a good scrubbing to clean them up. Then they all received a blasting in the glass bead cabinet.

So over the next few days I was able to get all my samples sprayed and the actual decision making process of what colors to chose could begin. After comparing samples and getting 2nd, 3rd, and 4th opinions on what others thought I finally settled on 4 colors that would serve as the palette. HD bead blast silver, Anodized Aluminum, Wrinkle Black, and Tuscan Matte Black was the direction I was headed.

The chosen colors. Clockwise from top left; Tuscan Matte Black, HD Bead Blast Silver, Anodized Aluminum, Wrinkle Black.

However I was still not ready to jump full into the final stage of powder coating without first shooting some more samples. I decided to take some of the old engine parts I had, that were broken and useless, and shoot them with my color samples to see how things would work out in real life.

Cleaned and bead blasted sample cylinder ready for powder coating.

I started by coating the cylinders and cylinder head with the Wrinkle Black and it was a good thing I did. The powder coating aspect worked out great however I now had second thoughts on using the Wrinkle Black. The comments I received from others included that it looked like a BBQ that hadn’t been cleaned for 12 years, to it looks like a truck bed liner, to it looks like a big ball of oil and grease. I agreed and therefore have decided against using the Wrinkle Black. I have since changed my mind to Tuscan Matte Black for the head and the jugs however I have no samples to shoot therefore my good parts will get sprayed in hopes that I am making the right choice.

Wrinkle black test cylinder. This color is not going to work. Will try for the Tuscan Matte Black finish on the good cylinder.

I had better luck with the Anodized Aluminum color. I shot a broken side cover with the color and it worked out great! The color is very close to the factory looking silver used on side covers. The texture is nice and smooth and I think the color will contrast nicely with my cylinders and engine case.

So with my testing complete it will be time to move onto prepping the real parts to receive a powder session. The prep is always the most time consuming as it involves out gassing, bead blasting, washing, and masking. Hopefully my inexperience won’t shine through.

Old side cover used for color sampling of the Anodized Aluminum powder coating.

  1. Mike says:

    I would not powder coat the engine head cooling fins. It will tend to hold the heat in and not allow the cooling that should take place. I have run into this before.

    • gordsgarage says:

      Hey Mike, thanks for the heads up. I researched this previously and knew that this was a common concern when dealing with air cooled motors. I suspect that from an engineering, thermodynamics, and practical standpoint the powder coating effects are a legitmite concern however I know of many people who have done it and have had no ill effects. If I was running a larger displacment performance engine I would absolutely not coat the cooling fins however I am going to roll the dice with my 16.5 horsepower 160cc twin. There is always an element of fun when chancing it.


      • Matt McLeod says:

        I have been wondering about the same thing. I have just bought a PC gun and powder thanks to your articles Gord. Also I’m working on a resto project for my early 70’s Harley Sporty.

        This is a good article about powdercoating for bikes, from a guy who seems to be an industry expert (you might have already read this Gord, but for other visitors it might be useful)

        Essentially, if powder is just another method of applying an inorganic coating (like paint), and everyone thinks its ok to paint jugs and heads, why not PC them? Considering HD do this from the factory (apparently) I figure they’ve done their research and spent plenty of money on it.

        Also, as a mechanical engineer, I do remember enough of my university thermodynamics classes to know that radiant heat transfer is a function of the “color” of the emitter, so black is good. WRT to convective heat transfer, it gets a bit more complicated, and IMHO beyond the scope to bother trying to figure it out for a garage project.

        I’m going to shoot my barrels in high-temp powercoat on my spare engine before I bore them. On my primary engine I’ll leave them bare or use engine paint (not decided which way yet) and run with them. Using an IR thermometer I should be able to start taking temperature measurements under operating conditions to see what the *real* temps are, not what the internet armchair experts think.

        Anyway, love your site Gord, and get updates in my RSS reader. You’ve inspired me to bash out some articles as well for my projects.

        Melbourne, Australia

      • gordsgarage says:

        Hey Matt, welcome to the addicting world of powder coating. I checked out your blog, cool projects, and bike! It looks like you have the same power feed for your mill as I do for mine.

        Thanks for the powder coating link, I have not seen that article before. Lots of really good information. It is refreshing to read something that confirms that I am on the right track with my technique and processes. I have bookmarked the link.

        I have heard the exact same thing that you mentioned, black is supposed to be the best for heat dissipation. My understanding is that normal temp powder coating works fine for the air cooled engines as the fin temperature is not excessive. I agree with you though in checking the temps yourself is the smart way to go. My concern with using a high temp powder is that the oven bake temperature is typically higher and therefore I fear excessive out gassing. Even though I outgas my parts first at 550 degrees for a couple hours I take comfort in knowing that the cure temp for my powder is only 375. I think that if I was to shoot high temp powder I would strongly consider using a outgas primer first however this may not be the best for an air cooled part since now I have just thickened up the coating. AARGH!!!!!!!!!! Just can’t win! 🙂

        Keep me posted with your Harley Sporty rebuild, I would love to see the progress.

        Thanks for supporting my blog, I appreciate the great feedback!


      • Matt McLeod says:

        Well there’s a pretty good chance I’ll stuff it up (at least the first time) so I’ll let you know how I go….!

        Thanks for the comments, and keep the articles coming. Also your photography kicks ass and is always a highlight of your site.


  2. Kristof says:

    I think your color selection is great.
    What is your degassing process?

    • gordsgarage says:

      Hi Kristof, I have learned that powder coating has one thing in common with anodizing, you spend most of your time in prepping of the parts. As far as the powder coating goes I outgas using the oven. I first clean the part with solvent, degreaser, and pressure washer. I ensure all the gaskets are scraped by hand and that the part is a clean as I can possibly get it. I then outgas it in the oven at 550 degrees F for 2 hours, the higher temperature opens the pores up and bakes out all the oils. After I then glass bead the part, I keep my blast cabinet very clean and free from oil. It is important that the outgassing takes place BEFORE the bead blasting as bead blasting a part that hasn’t been degassed will only force the oils further into the pores and cause contamination. There are podwer coating primres designed to prevent outgassing, the idea is to coat the part hot athereby locking in the oils with the approved primer.

      Glad you liked my color choice, hopefully it is the right one.


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