Powder coat question

Ok, who are the refinishing experts here?

As you may or may not have been reading, I'm trying desperately to breath life back into an '83 XJ Turbo. One of my concerns is the finish on the heads. It looks pretty terrible. Most of the paint is gone and something needs to be done.

A friend has graciously offered to powder coat the heads for me in the color of my choice. Almost sounds too good to be true! Then I got to thinking. This is an air cooled bike and most of the cooling comes from heat disapating through the fins. How would powder coat affect this? Then I got to thinking more. This is a turbo so it must run hotter than even a standard XJ.

So here's the question. How do you think powder coating would affect heat disapation? Am I likely to cause myself more trouble by doing this than just re-painting it?

I know that Harley powder coats some of their heads, but I supect I will probably turn more than the 3 or 4K rpms that their used to.

This bike does have an oil cooler, so that would certainly help.

All opinions welcomed!

Greg

 

There's a topic somewhere in here were some of the experts explained this in great detail. You might try the search fucntion.
I'll see if I can find it to.

 

Here you go.
http://xjbikes.com/Forums/viewtopic/t=843.html

 

Powdercoating won't stand up to the heat. Powder is baked on at 200 degrees Celsius for twenty minutes. If the head temps reach this temperature then it will continue to bake the powder till it is overbaked and then it will just start flaking off. Being aluminium, the heads would have to be chemically treated in a chromate dip for better adhesion. This would mean the bores would have to be honed afterwards to remove the chromate from inside the bore.

I have my own powdercoating oven at my business so am very familiar with the pros and cons of powdercoating. I powdercoated the muffler as a temporary cover up till I made a new muffler. The finish stood up to the temperatures for three month then started to peel just where the muffler met the headers due to the higher temp from the headers.

Go the paint. you won't regret it.

I could powdercoat the frame on my XS1100 but I am going to paint it in gloss black instead. IMO the finish of paint is easier to clean and maintains a shine for longer.

Cheers
HG

 

I powdercoat stuff all the time.
Headers have to be done in high heat. 1500 farenheight powder. The heads, valve covers etc that I have done in regular powder will easily hold to the 200 they will get to, they can stand 400 for a good while ...
High temp powder for heads if you are really worried. heat dissipation will not be a problem, the powder conducts heat just fine ... and your 4 cylinder gets plenty of air, better than the back cylinder on the harley ...
Cool.
Srinath.

 

Sorry to be the bearer of bad new srinath, but if you paid for 1500 degree powder coating then you were ripped off. No such powder exists. You may have had 1500 F paint baked on but powder has totally different property's to that type of paint.

Powder is basically put on in a powder form and when heated it melts the particles together to form a solid coating. Just like a cake in the oven, if left to long on the heat and will burn. When it is overbaked it becomes brittle and will flake off.

Powdercoating will not last more than half an our on header, less if done over chrome.

Jeel free to look up the product specs on pwders at http://www.jotun.com . Most have a very low flashpoint.

 

Its lasted a good while ... no sign of chipping etc, and While some of it is over chrome, the most of it was on rusty pipe, which has had the chrome come off.
http://www.headercoatings.com/
OK The stuff is flat black and the powdercoating guy did mine, and he couldn't do shiny black he said. Maybe its ceramic.
Now Spectrum powdercoating (in Menlo Park CA) also used to advertise powdercoating headers many years ago.
Cool.
Srinath.

 

Ah, Ceramics are a different kettle of coatings. Yes, Ceramics on the headers is one of the best ways to get a long life out of them. Not sure about putting it on the heads though as it is a thermal insulator. I would expect that it would keep the heat in unless they use something like JET HOT TDC which is designed for heat dissapation. Not sure if it's a caramic or not though.

Ceramics are a bit different to powdercoating as they are thermally applied(or plasma).

 

The plasma coatings are the neatest stuff! Jet Hot uses that process. The process literally sprays molten metal of choice onto the part. VERY durable and lasts a very long time.