Author Topic: Engine paint advice please.  (Read 607 times)

Offline David_N

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Engine paint advice please.
« on: December 03, 2025, 05:55:18 PM »
Question for those who have painted their engine.

I've pulled the motor out of my 550 k4 to clean and paint it.

I've ordered Simonize VHT31D engine enamel.

In some places the 48 year old paint has flaked off.

Does it need an etch primer or undercoat or both?

Should I strip all the old paint off back to bare metal or rub it down & blend in where is flaked off?

Thanks.

Offline Rayzerman

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Re: Engine paint advice please.
« Reply #1 on: December 03, 2025, 06:07:48 PM »
You don't want any flaky or chipped paint... so, normal prep for paint, clean, sanded, etc.  I rinsed it down after with isopropanol/water ~50-60% mix.  Air dry with compressor.

I did not use a primer, don't want too many coats on an air-cooled engine.... two light coats of Honda Cloud Silver (Duplicolor DE1615 is the equivalent).  Let sit a week to let solvents migrate out, then start the engine to "bake" it a bit.
'72 CB350F, 2010 CBF1000FA

Offline DomP

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Re: Engine paint advice please.
« Reply #2 on: December 03, 2025, 06:14:33 PM »
I used exactly the same simoniz vht paint.  My engine was really grim and corroded, a wire brushed and sanded until I had no obvious corrosion, washed and painted it then did the 'oven job' on it.  It stinks so make sure you open all windows and after the Sunday roast!
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline exvalvesetdabbler

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Re: Engine paint advice please.
« Reply #3 on: December 04, 2025, 09:16:01 AM »
I used spearex VHT enamel. SP127.  Not an exact match but is durable.  I think the brand is owned by Holts now but still under the VHT name

If you have a look in the gallery pictures there are a couple of images of my 400 posted under the same user name.  The top crankcase half is original paint , alternator case, rocker cover and sprocket cover were done in the early 90's with this stuff.

I just degreased with gunk then lots of scrubbing with washing up liquid. Rubbed down wet with 400 wet n dry. Baked them in the oven to draw out any remaining grease,  wipe down with paint thinners and then painted.  Once dry baked them in the oven slowly increasing the temp up to 100.

There is also a new colour called nu-cast but I haven't seen it with my own eyes though.

Regards
Dave


Offline David_N

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Re: Engine paint advice please.
« Reply #4 on: December 06, 2025, 11:16:25 AM »
I used spearex VHT enamel. SP127. 
 Once dry baked them in the oven slowly increasing the temp up to 100

I don't think I could lift the whole engine into the oven 😊

Offline DomP

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Re: Engine paint advice please.
« Reply #5 on: December 06, 2025, 01:56:40 PM »
I used spearex VHT enamel. SP127. 
 Once dry baked them in the oven slowly increasing the temp up to 100

I don't think I could lift the whole engine into the oven 😊

Be adventurous, go the whole hog and split it!
1975 XS650B
1976 CB550F1 current project
2012 Triumph Daytona 675

Offline exvalvesetdabbler

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Re: Engine paint advice please.
« Reply #6 on: December 06, 2025, 06:25:19 PM »
Alan Millard uses his gas BBQ

Offline Rayzerman

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Re: Engine paint advice please.
« Reply #7 on: December 07, 2025, 06:32:45 PM »
I painted my engine in frame, lots of masking tape and paper, lol.  Came out perfect......  these paints take quite a while to ultimately cure, so let be for a week or so, then you can bake at around 100F recommended..... however, just fire up the bike (with a cooling fan of course) and it will harden up some more.  Note, I did not use any kind of clearcoat, I did not want any extra layers...... before and after.  I used caps to preserve the original finish on the engine bolts.....





'72 CB350F, 2010 CBF1000FA