motor paint

i was wondering if anyone knows if i can paint the motor on my 85 xj 750 im going with a solid black theme on my bobber project and wanted to paint everything black including the motor. but i did read that there is a overheating problem if i paint the motor is there any truth to that???

 

Im pretty sure you can, Ive seen a lot of people on here paint there motors and I never heard them say they have had a heating problem with it. The problem is, typically the paint a lot of people will use cant hold up and endure the torture a exposed engine like that, and will end up chipping, flaking, and be a huge pain. So it may look good for a month or two, maybe even a year, who knows? But when it does, it will be a huge pain. If you are to do it, research some quality paint to use, anything out of a spray can probably wont give you the best results.

 

I was pretty impressed with the VHT ceramic epoxy paint I used on my rusty exhaust header...I've never seen anything stick to hot metal, much less chrome exhaust, so well.

I got it at O'Reilly's auto parts, about $12/can.

I can see where some people might speculate about overheating...this is similar to the ceramic coating used inside single wall drag pipes to prevent discoloration by way of it's insulating properties...but that coating is MUCH thicker...

Anyway, I suspect it may retain a small amount of heat compared to bare metal...I'd very much doubt if it added up to enough to cause an overheat...unless I hear it first-hand from someone it's happened to...otherwise I'd say it's one of those well-intended myths started by someone overthinking things...

 

A surface painted black (a thin coat) radiates 20% more heat than a bare surface (unless the surface is naturally black) and a polished surface radiates slightly less than a cast surface.

Mercury Marine found this out in the '60's and has since painted every motor black. They used to come in a variety of colors.

 

I've tried to point this out to people when they are considering putting chrome covers over oil filters and driveshaft tubes...which only reflect heat back INTO the part, and interfere with radiant cooling.

They never listen.... :cry:

 

time to ride is right black dissipates heat pretty well. i have painted 50-75 motors never had a problem with heat . 1 thing i do want to tell you the drying process after its painted let it dry for a day then start it up let it run for a few min to get the paint hot do not drive it because the paint will become tacky and road dirt will stick to it do this several times and you will have a durable finish. a chrome cover on the oil filter probably isn't a good idea never herd of a drive shaft cover being a problem if your differential is getting that hot you have problems actually a chrome cover would give the drive shaft more metal area to dissipate heat

 

The VHT needs to be "burned in" right away after it dries to the touch (which is like ten mins, it's very dry stuff)

I fired the pipes as soon as I could get them back on. Paint is so tough and sticky, I even took a hit from a big chunk of concrete on a ride, it dented the pipe but did not chip the paint...GREAT stuff...

But as I said, this is ceramic epoxy, not typical enamel or whatever. Engine enamel sucks, just my opinion.

p.s. the VHT is resistant to 2000°F...yes, that's two thousand degrees. I was initially skeptical, but I am a believer now...

 

i could definately see it on exhaust . I did not know he was painting exhaust. vht makes very good paint . i like their frame epoxy does a really nice job on frames if you can survive the fumes when applying it . i know what you mean by tacky thats why i told him to start it let it warm and cool do this several times to cure the paint. i have had really nice motor paint jobs get ruined when the paint gets tacky while warming it up its almost like a magnet lol

 

Yeah I seem to remember that...enamel starts to feel like silicone rubber does at some point in the curing process, if you do it wrong...

I don't think he's painting exhaust, but I suspect it would work real well on engine castings...I'm gonna repaint my cylinder block with it soon, let you know how it holds up...

 

I have a painter friend who works in a dealership body shop...he's done some nice engine paint jobs that held up real well...he went to a trade class where they taught how to paint engines and such using the same PPG/Deltron paints they were using on exterior body, only with some mods to the mix...that stuff is polyurethane, no?

Is that what you use?

 

i dont get that fancy i use 500 degree motor paint there is really no need to use 1500 degree paint. the hottest part is around the exhaust ports i have never had it blister or peel even on bikes i have ridden down main street during bike week they get so hot from sitting in traffic makes you wanna cringe as long as it is clean and rough surface your ready to go

 

The paint wont hinder cooling of the engine.

In fact, having a semi gloss or flat paint on the engine will increase air cooling by increasing surface area

Under a microscope you can see it has texture, in turn increases surface area, thus the air flows over more of the engine.

My favorite cheap stuff is duplicolor engine enamel. The low gloss black looks great (it's not flat at all and goes great with any paint job)

 

Man, I hope that's not entirely true, as I've already apinted hald my exhaust with that stuff during my winter project. Mine's been sitting there, painted, for over a week now, untouched.

 

thank you guys for all your help and answers. i wont have the opption of starting the motor with the paint intill i get everything back from powder coat. im gona paint the motor off the frame. but i will make sure to heat it and dry it before i do ride it a couple of times. as for the exhaust im just gona wrap it with exhaust mesh tape. any suggestions on how to prep the motor for paint do i just use regular grease remover?? or somthing alcohal based?

thank you again for all your replys

 

my previous owner sprayed some type of aluminum colored paint on my motor. and a lot of other parts. It's horrible! flakes off with a thumbnail.

I've spent time removing it where I can, after I'm complete I'll probably do a black coat.

 

You could look into soda blasting. You definitely want everything to be spotless. The better the prep work, the better the results will be. I believe these paints have a high heat primer as well, it would probably be a good idea to use that as well.

 

I would NOT paint the motor itself. Clean it up, pressure wash it, sand it, buff it, and paint the accents (removable parts, like caps and stuff only). that was, it'll still have a sporty look to it while keeping the vintage look. PAINT ON THE MOTOR WILL CHIP-OFF FAST, UNLESS YOU POWDER COAT EACH ENTITY INDIVIDUALLY WITH HIGH HEAT PAINT WHICH WILL COST ALOT MORE THAN YOU SHOULD SPEND.

 

the only way paint will chip is if it is not prepped properly i have painted probably 50-75 motors and never had a problem. just like anything else its all in the prep

 

Proper surface preparation is paramount to a good looking, long lived paint job. I've used PJ1 CaseSaver with great success for years. They also have a nice Frame Black.
I sealed up my 650 engine, bead blasted it, washed it down with alcohol and shot it with PJ1. Easy day and chips are not hard to fix.

 

A friend of mine painted his and it ran a little hotter but had no issues but your results may very