ST90 engine painting questions

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Shamrockwill

Member
I am restoring an ST90 and have decided to paint some engine parts this Saturday as it's supposed to be 78 degrees and down to 55% humidity. After reading many threads on the subject I'm planning on going the rattlecan route and painting the stator cover, sprocket cover and right crankcase with Duplicolor BCP103 silver caliper paint. The specific questions I have that I haven't seen answered in other threads are: Since Duplicolor to my knowledge does not make a caliper clear coat, can I clear coat over the caliper paint with Duplicolor engine enamel clear coat? Secondly should I apply all my clear coats within an hour of applying the first coat of color or should I wait the 7 days for the caliper paint to fully cure before I apply the engine enamel clear coats? And finally I have seen much debate on these forums as to what to use for primer or whether primer should be used at all on aluminum engine parts. So, hopefully without too much debate....do I need to use a primer before the caliper paint? and if so, which kind? Thanks as always!
-Will
 
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b52bombardier1

Well-Known Member
I think . . . not sure, but it will help if you use a 2k catalyzed clear coat over your silver paint. This type of clear coat is about 21 bucks for a rattle can but it has a small canister of hardener / activator inside it. This clear is very resistant to hot oil and fuel spills on your new paint.

https://www.ebay.com/itm/Spray-Max-...704795&hash=item1ecf7d44f7:g:vr0AAOSwd~RZOs-L

If you want to buy it locally, forget about Lowes, Home Depot and Walmart. You will need to go to a specialty automotive paint store for this stuff. Also be advised - this stuff CAN KILL YOU in a confined space without adequate ventilation. Use a NIOSH respirator due to this stuff containing isocyanate.

Rick
 
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b52bombardier1

Well-Known Member
Yes, I think so but that timing is what I'm unsure about. Try getting the data sheet on these paints or read the instructions carefully. If the clear is sprayed too soon, its solvents might loosen the silver. Also be advised that your "pot life" working time for the liquid inside the 2k paint can is only maybe 36 hours. After that, it'll start to become too stiff to spray. This time begins when you push the red cap on the bottom of the can so schedule your silver painting accordingly. You will be unable to use the remnants of the clear inside this rattle can on anything else after 36-48 hours.

Rick
 
red69

red69

Well-Known Member
The 2k clear over a basecoat requires less than a twenty-four hour interval otherwise re-coating the surface with basecoat is necessary. In your case I would use the clear within about six hours of the initial paint coat so that there is a chemical bond.
 
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Shamrockwill

Member
The rattlecan basecoat I have says to apply additional coats within one hour or after 7 days. Can I apply the 2k clear within that first hour?
 
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b52bombardier1

Well-Known Member
I'd make your first pass coat of 2k clear light and thin over your silver so that there's not a lot of excess solvent on top of your silver. Let that flash off, dry a little . . . cure a little, whatever you want to call it for maybe an hour. Then make your next coat of 2k clear somewhat thicker until you get the number of coats you desire. You will not need a thick coat of this clear as it is very resistant to fuels and oils so just don't go overboard with too much here. I most recently used this on my 72 Honda CB500 fuel tank after dent repairs, POR 15 and a repaint and went a little thicker than I'm advising you here only because I needed more thickness for wet sanding to bring out the shine.

Since you won't be wet sanding an engine, you don't need a lot of build thickness.

Rick
 
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