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Discussion Starter #1
Gang,

I am contemplating powder coating my CB500T engine (silver or black) ... however, it needs some work done like boring the cylinder heads and valve lapping ... any opinions on when to coat? Would you do it prior to the work or after?

Thoughts? Thanks Bill
 

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I'd paint your engine rather than powder coat it, and do it after you've had the work done. Powder coat is applied at about 200 degrees centigrade, about 400F in old money. You'll need to mask off before Coating, and bear in mind you'll need a heat resistant masking tape, and silicone bungs for the threaded holes, you could screw in old screws, but they will get covered in powder.
Have a look at YouTube powder coating for advice. www.frost.co.uk or Eastwood hot coat powder coating. www.eastwood.com
HTH
 
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I'm afraid this is going to be an unqualified opinion, because I've never tried it but . . .

. . . do all the internal(?) work that needs to be done first and paint/powdercoat after that. Reason being there's too much potential for damage to the finish if you do it the other way round. Some of the work you want done (boring cylinders) will require bits to be held in place, and that could necessitate things like vices. That's not to say the people doing the work won't be very careful, but it's easy to bump/ding/whatever a finish when you're handling freshly coated parts. Added to which, you can go to town cleaning the residue of any internal work with stuff like acetone when there's no finish on the outers. Your choices of cleaners quickly start to limit once you apply coatings. Oh, and if you're going to do stuff like boring and valves, make sure you get the head and barrel mating faces checked for flatness. Making absolutely sure they're flat before you rebuild could save you a lot of time and effort later on.

Having said all that, I'd be very wary about powdercoating cylinder cases. I can't find a recommended running temp for these engines, but given that they're air cooled, it's gonna be hot. Powdercoat in its raw form will start to melt at 150deg c, so you might find it won't hold up to the sort of heat that's generated inside the cylinders. But even if it does hold, powdercoat encapsulates the surfaces it's applied to, and that's not a good thing from a heat dissipation perspective. Again, you need efficient air cooling and as much heat out of the engine as quickly as possible; powdercoat won't help with that.

Hopefully someone who's done it can give you some better insight. I tend to leave my engines alone after they're vapour blasted because the finish is pretty good without anything on it and apart from darkening a little over time, it doesn't need any special treatment - that, and I never need to worry about whether the finish will be affected by stuff like carb leaks). If I were going to need colour, I'd be inclined to consider heatproof paint, rather than powdercoat.

Hope that kinda helps . . .
 

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I have painted (sprayed) cylinders using black disk brake spray pack, quite soft till the engine had been run for an hour or more but has stayed on for a couple of years and about 2000 miles.
The cylinder looked untidy before with damaged fins and weather discoloration. The paint disguised this well.
 

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I'll throw another opinion into the mix.

I'm going with high temp cerakote. That's basically fancy vht high temp engine paint that a certified shop will apply. They have a few colors to choose from black, silver, titanium, and gold. Same typical process, they will bake the cases, blast it to remove any residual grease and grime, then apply the cerakote and bake again. I'm going with a two tone black and titanium job, and going to run me about $500, which is similar to powder coat rates. If interested go to the cerakote website to find a qualified shop that applies it near you.

As for prep, yeah I'd say get all the internal stuff done first, get the cases cleaned up and ready for reassembly prior to coating. My theory is that I should get the cases back, then start right up on reassembly, don't want to have any opportunity to ruin the new finish. Only problem that I personally ran into is that I've had my head rebuilt with new valves, guides, seals, and beehive springs. Having all this work done prior disqualifies it from being coated, I'm concerned that the seals will melt with the temps used to clean the cases and apply the cerakote.

That's like just my opinion man....

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IMHO I would do all maintenance before painting to keep from damaging the paint. Powder coating , the coat will not raise the temp more than a couple degrees . The powder will cure at about 350-450 degrees depending on the powder. On motors Iv coated the operating temp at the plug was around 280-290 degrees at the plug and 380-390 at the exhaust. Iv coated cases, and side cases with great results, but use high temp paint on the cylinder and cylinder head. I dont assemble any thing until the paint is cured. Mask of parts that will contact other parts on assembly . Just my thoughts. I had to buy high temp on line ,the local guts dont carry it.

Bill H
 

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I'll toss this in as well, its reasonably cheap, bakes on once engine gets to operating temp or can be baked on in an oven or BBQ grill and is hard as a rock and fuel/oil resistant. I have it on my 450 and am very satisfied with it. Didn't cost 500$ to put it on either.

https://www.duplicolor.com/product/engine-enamel-with-ceramic/

As a general rule for all MC/CAR building, do all machining, mock-up assembly, and any other work before painting/powder coating. No reason to paint/PC 2-3 times.
 

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The local powder coating place would not powder coat an exhaust for me. They said the would not coat any high-temp parts because powder coat is combustible at around 400f. Your engine shouldn't be getting that hot, but, I don't think I would chance it. A decent paint job is the way to go.
 

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One thing I forgot to mention. You can change sleeves at around 350 degrees, one member stated he did it at 250, thats the curing range of powder. Iv changed the sleeves in several cylinder heads and I remember a 305 that the sleeves just fell out of at 350 degrees.
You would have to be careful of the position of the cylinder while curing the powder. You have to pre heat alum to get the air out thats left after casting to keep from having bubbles in your finished coat. Pre heat is 400 degrees for up to an hour depending on the thickness of what your coating. Anyway your heating your cylinder twice at the temp of or higher than sleeve removal and I dont know if they would return to the right height in the cylinder. .003-.004 can cause an oil leak at the head gasket. I had a 305 up and running and had to tear it back down and have the head dressed to stop a leak because the sleeve was to high. Bottom line I dont powder coat cylinders.


Bill
 

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never?
 

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Personally, I wouldn't either. I think there's something to the thought that powdercoat might make heat dissipation worse, it's generally thicker than the average couple of coats of paint. I've always gone with the natural aluminum color, or high-temp silver or black paint if you must put something on them... but I'm not a black cylinder or head kind of guy anyway
 

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Discussion Starter #16
Thanks for the advice everyone ... I decided not to powder coat or paint the engine casings at all ... I will polish some of the "covers" but leave the casings alone.
 
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