engine painting

has anyone successfully painted an engine without teardown?

 

Yes. It's not really hard - you'll need to remove the tank, body panels, carbs, exhaust and such to be able to reach everywhere but that can all be done pretty quick.

Clean the engine thoroughly with an engine cleaner/degreaser, of course (prep is everything), and have at 'er. Be sure, of course, to use a high-heat engine paint. Be careful about the intake, exhaust, and case vent - cover up securely.

Without a lift, you're going to struggle to get a good paint on the oil pan/underside of the engine, but that's covered by the exhaust system anyways.

David Cormier did this, with pics, in his thread: http://www.xjbikes.com/forums/threads/82-maxim-xj1100-dark-knight-build.100250/

 

I want to do some engine painting but not until I find a rattle can that can come somewhat close to a factory powder coat finish as far as durability. Until then, I'll be polishing and cleaning the engines

 

I've had great results with VHT gloss black caliper paint and VHT gloss clear coat. Sturdy, and being caliper paint it handles the heat fine.

I find I can get extremely good results with rattle cans, but finish depends on surface prep more than anything else, though.

Once heat cured (Yay for air cooled engine operation) it's very durable. As durable as factory powder coating, no, of course not. But no paint is really going to get very close to that.

Still, my calipers (first things I used the paint on) have survived 10,000+km of riding over the year without a mark on them, so that's something.

I'd paint my engine, but to be honest I'm just too lazy to clean it *that* thoroughly.

 

Use acetone for cleaning before painting... It will cut through damn near everything. It will make a HUGE difference for paint adhesion. I did my cover with high heat paint. The previous owner was struggling with a fuel leak as you can see...

Pretty happy with the results...

 

I did the same. Mine wasnt quite that bed to start, but was really worn and the exposed aluminum parts where really rough. Polished it up, clear coated after painting.



Mirror finish on the fins/lettering and a nice gloss black elsewhere. I'm very happy with it. Taping off the fins/lettering when painting the black kinda sucked, but I was afraid if I painted the black then sanded+polished the fins I'd made the black before clear coating. Carefully trimmed tape seemed an easier approach.

 

Now THATS pretty! I started to tape things off... then realized what a major PITA it was... What I did was:

Clean vigorously with acetone, then cut and buffed the lettering and fins (harbor freight kit, black, red & white), finishing with a round of "Mother's Mag and Wheel Polish." Trying my best to stay away from everything else... then one more round of acetone (keeping away from the buffed surfaces of as to not remove any of the luster left behind from the mothers). Then I sprayed over the whole darn thing... Covered EVERYTHING with the paint... Then before it dried hard, while it was still "gummy" I was able to use a straight razor to cleanly peel the black away that I didn't want on the visible aluminum surfaces.

After a good cure and long engine run and cool, I buffed again... Worked great!

 

xj4ever paint section

XJ PARTS CATALOG, SECTION O: EMBLEMS, STRIPES, DECALS, PAINT

 

Yeah, it wasn't a lot of fun. Taped over everything then painstakingly cut it to fit with an exacto knife... But it took several attempts in places as the tape would year instead of cut nicely here and there. The lettering was the worst.

[/Quote]What I did was:

Clean vigorously with acetone, then cut and buffed the lettering and fins (harbor freight kit, black, red & white), finishing with a round of "Mother's Mag and Wheel Polish." Trying my best to stay away from everything else... then one more round of acetone (keeping away from the buffed surfaces of as to not remove any of the luster left behind from the mothers). Then I sprayed over the whole darn thing... Covered EVERYTHING with the paint... Then before it dried hard, while it was still "gummy" I was able to use a straight razor to cleanly peel the black away that I didn't want on the visible aluminum surfaces.

After a good cure and long engine run and cool, I buffed again... Worked great![/QUOTE]Oh, this is brilliant! For some reason, I only considered trying to clean off the wet paint, or sand off the cured paint, but never even remotely considered peeling it off like that when partially set.

Also, let's here it for Mother's: that stuff can make anything look awesome.

 

Here’s my recent engine painting for my build. Had the engine out of the frame. Spend a few days cleaning with degreaser. After I got to a point I was happy with, I taped off everything. A few light coats of primer, then black, then clear. I used the rustoleum engine paint. Turned out decently well. I didn’t get under the engine. But that really won’t be seen so I’m not worried.

 

The factory paint is single-stage enamel.

 

Nice!

Could someone here speak to any potential problems with it being more difficult for a fully painted engine to shed heat?

Or is that not an issue?

 

not an issue yamaha painted motors from the factory

 

Nah, the insulation value of a thin coat of paint is incredibly small.

 

I've wondered about that too as I have seen numerous automatic trans failures due to someone painting the entire case. I'm sure abuse was a factor as well but good to know

 

650 seca has a fully painted motor.
read the paint section and you will see how much of the motor is painted or clear coated

 

If a transmission failure was due to paint, it was due to getting paint inside somewhere (a vent, poorly taped line, etc) or some other abuse.

It was NOT due to heat. While it's possible you could end up with a slightly warmer engine, it's going to be by very small fractions of a degree. You could also end up with an engine that cools better due to higher black body radiation vs. raw aluminum, but again by such ridiculously small fractions of a degree it's not going to have any affect when you compare it to the operating temperature range of the engine/transmission.

If transmissions where so sensitive to heat that an increase of a hundredth of a degree could cause failure, we'd have very serious problems.

It's important to understand the scales here. That layer of paint's thickness is measured in microns, so any impact it has is going to be so incredibly low you'd be unable to measure it because you'd be unable to control other variables close enough to see a difference.

 

from xj4ever paint section

Cylinder Heads and Cylinder Jugs:

On the top end of the engine, most XJ engines feature the Code 162 Satin Silver Metallic flat metallic painted cylinder jugs and cylinder heads, with Code 98 LGB low-gloss black or Code 33 Competition Yamaha Black semi-gloss black cylinder head valve covers, while all 1981 XJ550 models, and the 1981 and 1983 (but not the 1982 model!) XJ750 Seca models featured un-painted, machine-polished and clear-coated valvecovers.

Other models are equipped with Code 58 Intense Gloss Black painted cylinder heads, cylinder jugs, or both. On models with black-painted heads or jugs, the edges of the fins may or may not be painted black also; if not, they have a natural cast aluminum look to them.

Some later model (1983-later) model engines may have come with un-painted heads and jugs.

Once again, although not originally used, we strongly recommend a high-temp clear-coat be used over all painted surfaces for protection.

Upper and Lower Main Engine Cases:

Most XJ engines feature unpainted, bare natural aluminum finish on the lower (bottom) engine case, and a satin silver metallic painted upper engine case----yes, your upper engine case was painted (we've seen a few exceptions to this situation on some original models, and don't know why, but we'll say that 99% of all original engines arepainted). Although most painted engine parts were not originally clear-coated, but we will recommend that you do apply a thin coat of clear to help protect the paint against fuel, oil, and chemical spills.

Other models, such as the XJ650 and XJ750 Midnight Maxims, XJ650RJ Seca and XJ650 Turbo models, 1986 XJ700 air-cooled models, all XJ700-X models, 1983 XJ750 Seca, and the XJ900RK models have gloss-black painted upper and lower engine cases and engine side covers, again without any clear coat originally (but recommended for restoration purposes).

On all models, the engine oil pan ("sump") was always left un-painted, and we recommend that you do the same.

 

My upper case has (or, more appropriately, had) the silver factory paint. Not much remains now though. Black cylinders and valve cover, bare heads and lower case.