Topic: Lets talk about soda blasting and painting an engine

[rusty_tank]

Howdy folks. I have a 1978 CB550K that I've torn down to the frame and am rebuilding. This post is mostly about painting an engine while it's assembled or in pieces/piece by piece...

My focus is currently on my engine. It's out of the frame, head and jugs are off cuz of some head work and a gasket change. I'd very much like to paint the engine so I've been thinking a lot about prep. I've read that soda blasting is a great way to get an old engine prepped for paint so that's what I've decided to do. In order to have that done I need to put the engine back together, blaster needs the engine in one piece. This is where my question is...and I feel like it gets a little convoluted so bare with me. I've been guilty of over thinking things in the past and that may be what's happening here, you tell me...

...In order to get the engine soda blasted I need to re-asemble the engine. I've talked to a few people about painting the engine, in person and on the forum, and I keep hearing/reading that it's best to paint the engine piece by piece rather than fully assembled. Does that mean that no one paints their engine fully assembled? Does that mean I need to assemble the engine, gaskets, torqued, everything, have it blasted then disassemble it again for paint? If that's seriously the case I'll do it but I want to make absolutely sure that's the way it's done.

Next question is about paint and baking. Until someone on the forum mentioned to me the practice of baking after using a high temp paint I hadn't considered it. I have a good buddy who's painted his engine, he's talked to me about it and I'm sure he never mentioned anything about baking. Are there hi temp paints available that don't require you to bake? My buddies paint job is 5 years old or more and his still looks great.

Ok, hope that all made sense. I really look forward to hearing from you guys 

[calj737]

You can assemble the engine for blasting without the "internals" because after soda blasting, you'll need to flush the engine very thoroughly, and clear all oil passages. After blasting, you'll also need to clean the surface and wipe it down completely with Acetone or other paint prep solution as paint won't stick to soda residue.

Heat curing engine paint is a 50/50 opinion. There are those that do it and swear by it, there are those that don't do it and have equal results. VHT is a common brand of engine paint used by many.

Instead of soda blasting and painting, have the motor powder coated. It takes care of both steps (blast and paint) and having the engine fully disassembled is necessary anyway. Plus you have the added benefits of choosing different colors and finishes on different parts.

[rocs]

I didn't blast this but prepped it pretty well.

Paints the engine but polished all the tappets and covers.


More pictures in my build thread. Just finished this build yesterday.

[DaveBarbier]

I have it documented in my build thread, but I assembled it empty like Cal mentioned > had it blasted > disassembled and cleaned thoroughly > sprayed down with acetone > reassembled empty with rubber gloves > painted (didn't bake) > disassembled and built up the motor with internals > drank beer. Actually I was drinking the entire time.

[Stev-o]

I like Dave's procedure, especially the last step!   I painted my K4 engine with VHT paint while it was fully assembled, just removed the engine covers, no baking.
It's been a year and a half and still looks great. The key is prep. 

[70CB750]

I think I want Dorothy to be clean Aluminum, nothing else, no paint, just metal.

Is there a downside to it?

[Kenzo]

So you can paint a properly prepped, fully assembled engine, polished bits removed and masked off appropriate areas, etc...

...now in the future you have to remove something where the gasket has been painted in place...is it not a big deal that the gasket is painted? Is that how Honda and manufacturers do it?

Also I assume if you want the jug a different color it's just as simple as masking off parts not to be painted.

Thanks in advance,
Kenzo

[calj737]

I think I want Dorothy to be clean Aluminum, nothing else, no paint, just metal.

Is there a downside to it?

It will oxidize some over time. Vapor blast looks great and lasts!

[przjohn]

I am a fan of disassembling the motor, ultra fine glass beading, meticulous cleaning, VHT paint, oven time, and then assembly. Maybe it is old school but every part is thoroughly examined and then assembled like new. Honda painted this stuff before assembly so I  figure that is the way to go for me too. I can understand the painting of an assembled motor if you do not want to go into the motor but figure, hec, if you have it apart anyway?

[Kenzo]

So I see all of these beautifully soda & bead blasted motors before and after paint...I'm sooo jealous! 

I'm all about efficiency and I'm get'n old so my days are numbered.   

I hope to soda blast and paint my motor one of these days...

...Question, how important is it to get every spec of old paint off?

It would seem that the paint still stuck after 40 years after a light soda blasting ain't going anywhere and would be fine to paint over. Unless I find a good reason to open the motor I'll be leaving it assembled when painting. I'm not looking for perfect but I want it to last.

Thanks in advance,
Kenzo

[rusty_tank]

I want to thank everyone who responded to this thread. This has been an interesting experience.

To start, I have zero interest in disassembling the guts of this engine. I rebuilt this motor from the ground up about 5 or 6 years ago, partly with the help of the forum btw, and the engine's been a champ ever since. I only took the top end apart recently because I needed to change the head gasket and figured I'd have some machine work done on the head. I've been in touch with a guy near where I live who soda blasts. I asked him about the whole disassembling the engine, having the shell blasted then reassembling engine thing. He told me I DIDN'T need to do that if I didn't want to. He said if I bring him the engine all buttoned up, ready to go, he can blast it as is. So, word to the wise, you CAN soda blast a completely assembled engine. I'm only emphasizing that because I think most of the posts regarding that stated the engine be disassembled.

Regarding painting, after much thought I will definitely be painting the engine after it's buttoned up/assembled, not in pieces....and definitely not baking. For god sakes, while I'm syncing the carbs the paint will get baked on cause the engine will get damn hot.

[flybox1]

while I'm syncing the carbs the paint will get baked on cause the engine will get damn hot.

...exactly why you should have a fan on it 

[przjohn]

If you use VHT paint make sure you don't spill any gas, oil, or cleaning fluids until it has time to bake on the motor. The bike's heat will cure the paint, no doubt. The advantage to baking is you don't have to worry about a surprise petcock leak dripping down on your side cover ruining your paint. If you are going to be working on the carbs after fuel is in them and the motor has not cured take the time to protect the cases while working on the carbs. After you get the bike to temp and have the paint cured you will be fine. I don't know what it is about that stuff but it is more susceptible to fluid damage than normal paint until it cures.

[tlbranth]

So I see all of these beautifully soda & bead blasted motors before and after paint...I'm sooo jealous! 

I'm all about efficiency and I'm get'n old so my days are numbered.   

I hope to soda blast and paint my motor one of these days...

...Question, how important is it to get every spec of old paint off?

It would seem that the paint still stuck after 40 years after a light soda blasting ain't going anywhere and would be fine to paint over. Unless I find a good reason to open the motor I'll be leaving it assembled when painting. I'm not looking for perfect but I want it to last.

Thanks in advance,
Kenzo

Soda blasting is amazingly effective at removing the old paint. I've done several parts that way. I plan to paint my CB750K0 one of these days and I ain't taking it all apart to do it. I've blasted lots of parts before in my neighbor's blast cabinet using aluminum oxide media and used regular masking tape to keep the grit out. I've had no problems but I was pretty careful around the tape. My neighbor is a car restorer and told me he's painted engines with the stuff he uses on car bodies with no failures. The stuff he uses ain't cheap - $1000/gallon but there are cheaper alternatives. He uses epoxy primer under it which he says will stick to anything. If you're not game for that, he said, in general, avoid aerosol can paint - it's mostly propellant and thinned too much. If you can, buy a can of the same stuff and shoot it through a spray gun.

[rusty_tank]

If you use VHT paint make sure you don't spill any gas, oil, or cleaning fluids until it has time to bake on the motor. The bike's heat will cure the paint, no doubt. The advantage to baking is you don't have to worry about a surprise petcock leak dripping down on your side cover ruining your paint. If you are going to be working on the carbs after fuel is in them and the motor has not cured take the time to protect the cases while working on the carbs. After you get the bike to temp and have the paint cured you will be fine. I don't know what it is about that stuff but it is more susceptible to fluid damage than normal paint until it cures.

przjohn, thank you. That was super helpful information about the paint.

[heyitsrama]

I have my entire engine disassembled, i went through with a gel degreaser yesterday, then pressure washed all the oil out of the 2 engine casings. It removed most of the grease inside the engine, as well as most of the crud that was sticking to the outsides.

Tomorrow i plan to use my soda blaster to clean off all the old black paint that PO had on the motor, after that its back for another pressure wash, compressed air cleaning, pressure washed again, then acetone bath, and hopefully a primer layer for paint, I'm using VHT SP148 Primer // SP127 aluminum. I build this old oven out of cardboard, foil and a heat gun that way i can bake the parts. After that its hopefully off to assembly.


RIP my wallet. 

[DaveBarbier]

I've found that odorless mineral spirits in a spray bottle is the best to remove grease. Way better than any canned degreaser I've tried. And also cheap.

[70CB750]

I've found that odorless mineral spirits in a spray bottle is the best to remove grease. Way better than any canned degreaser I've tried. And also cheap.

I am old fashioned, I use gasoline

[DaveBarbier]

I've found that odorless mineral spirits in a spray bottle is the best to remove grease. Way better than any canned degreaser I've tried. And also cheap.

I am old fashioned, I use gasoline

Yeah, but mineral spirits is safe on plastic bottles and rubber parts and paint. Plus the odorless stuff won't kill you as readily. 

[70CB750]

You have a point just doing what I learned from my dad.

[Kenzo]

It just occurred to me that on these painted motors & cases(painted assembled)...that good old fashioned heat lamps will probably do a good job of degassing and curing the paint.  It's good enough for the automotive industry and better paint shops.



Cheers

[70CB750]

The body shop I worked in had a gas furnace heating up the spray booth.

[tlbranth]

I've found that odorless mineral spirits in a spray bottle is the best to remove grease. Way better than any canned degreaser I've tried. And also cheap.

I am old fashioned, I use gasoline

When I was a youngster living in San Jose, Ca., the only motorcycle shop around was a place called Cancilla Motors. One of the Cancilla kids was washing engine parts in gasoline one day. He took a break and went outside for a smoke. Yes, you guessed it. The fumes in his clothes caught fire and he was killed. Just sayin'.

[alacrity]

smoking is bad for you

[przjohn]

Luckily for me my wife has to travel now and then for business. That's when I bake the parts in the oven, but even before that, I run them though the dishwasher.