Honda Twins banner

1 - 15 of 15 Posts

·
Registered
Joined
·
12 Posts
Discussion Starter #1
I have a couple of different Honda bikes that I'm working on but currently I'm focused on my 1993 Honda XR 250. I've got it down to the frame and it's time to remove the stock paint and after some research I tried to use Aircraft (paint remover) to chemically remove the paint. After a couple of hours of spraying, waiting and scrubbing I'm going to sandblast it instead, this process showed some progress but I know that it'll take hours which blasting will save.

After talking to a couple of people in the powder coating and paint remover industry I need to know if the stock paint job on this bike is paint or powder coat? Or does anyone know if all Honda frames come a certain way or if they switched after a year? Any insight would help me choose the next path to go down.
 

·
Registered
Joined
·
711 Posts
I would doubt it is powder coated. Harley didn't start powder coating until '94 and I would assume (just making it up now) that the expensive lines of bikes were the first in the industry to receive new, expensive treatments.
 

·
Registered
Joined
·
1,363 Posts
I dont think they are coated but why worry about it. Just take it to some where and have it sand blasted. I do all my small sandblasting work but larger items I take to people that do it for a living. Just for info Eastwood has a remover that will take off paint or coat but its not cheap.




Bill
 

·
Registered
Joined
·
2,819 Posts
If bead blasting is available, it would be better than sandblasting, a lot smoother finish and perfect for paint adhesion. A sandblasted finish will need many more coats of primer-surfacer than a bead blasted surface to get the frame smooth enough for a glossy finish.
 

·
Super Moderator
Joined
·
24,208 Posts

·
Registered
Joined
·
1,363 Posts
Mike in idaho is correct. I use black diamond coal dust in my sand blaster. 50 psi for alum. 135 psi for steal.

Bill
 

·
Registered
Joined
·
755 Posts
The short answer is, painted. ;)

Here's a pretty good article on the history of powder coating technology.
 
  • Like
Reactions: Bill H

·
Premium Member
Joined
·
2,917 Posts
Don't think they even bothered with primer or undercoat, just black paint straight onto bare metal. Amazing that it has lasted as well as it does.
 

·
Super Moderator
Joined
·
24,208 Posts
I suspect that Honda used an electrostatic painting process, sort of similar to powder coating.
 

·
Registered
Joined
·
587 Posts
Depending on what year you're talking about, the frame may well have been stove enamelled. It was the forerunner to powdercoating, where a heavy paint type product was either brushed or sprayed onto the frame, and then the assembly was baked to cure the enamelling.

This is a pretty decent explanation of the pros and cons of stove enamelling v powdercoating and you'll probably be able to see why the former has largely fallen out of use from its list of bad points (hint: health and safety). Somewhat unsurprisingly, it's now very hard to find anyone who has the set up to do stove enamelling - at least on a small scale - because it's simply no longer financially viable given that there's a much safer alternative. And for that reason, it now tends to only be used by folks who do high-end restorations.

Knowing the chemicals and processes differ helps to explain why it can be very hard to precisely replicate the finish on old frames. Whilst the processes produce similar finishes, stove enamelling tends to have a greater depth of colour to it - even if that colour is almost always black on frames. And there's some debate as to whether powdercoat really is better or more durable - it's not as clear cut as folks who specialise in powdercoating (and therefore have a vested interest) often claim.

As to how to remove it, you can either go mechanical or chemical, and even then the method you choose may well come down to how much time/money you want to put in. The better mechanical methods involve wire brushes on angle grinders or shot/bead blasting. Using anything less abrasive is likely to be ineffective; more abrasive will damage the frame.

Chemical involves running a series of tests to see what the surface is susceptible to. I've found (by accident) that some powdercoat types can be softened by something as simple as isopropyl alcohol, but like anything, formulations will have changed over time. Some will now be more resilient, others less so. Whilst many of today's coatings will resist stuff like white spirit, they won't stand up to neat acetone, xylene or cellulose thinners. Wet a cloth with whatever solvent(?) you want to try, wrap it round a section of the frame and leave it for half an hour. Assuming it doesn't all evaporate, you may well find the frame coating softens to the point where it falls off.

If you're going to try paint stripper, look for a product that contains dichloromethane/methyl chloride. Not sure how easily available it will be in your area; it used to be pretty common over here in stuff like Nitromors but it's nasty stuff and so off-the-shelf products have been reformulated and as a result no longer have the same penetrating power.

And if it gets underneath, fuel (gas/petrol) will also lift some paints off fuel tanks. Don't ask.
 

·
Registered
Joined
·
2,837 Posts
Idk what it is, but it was some pretty durable stuff. It doesn't seem to chip, and seems pretty thick, where minor scratches will blend in. You'll clog up a lot of sandpaper trying to take it off.
 

·
Registered
Joined
·
2,819 Posts
Don't think they even bothered with primer or undercoat, just black paint straight onto bare metal. Amazing that it has lasted as well as it does.
Yes, the frame parts were coated as cheaply as possible with one coat of paint over bare metal. I noticed, when prepping my CL77 parts for paint, the only parts with an undercoat under the paint were the headlight shell, the fork ears and the tool box lid. The tool box body,air cleaner brackets and lower steering crown had only a thin layer of paint. As in most production settings, no money was wasted making the less visible parts smooth and shiny.
 

·
Registered
Joined
·
13,085 Posts
^^^and yet in most cases it was pretty durable. My drag bike CB450 frame still looks pretty good in many places... if not for the heavy rust in some lower areas, I'd probably leave it alone as it's plenty good enough for the purpose - and it's 45 years old
 

·
Registered
Joined
·
12 Posts
Discussion Starter #15
People of the internet, Disciples of DIY, fellow wrenches,

I'll have you know that I have successfully sandblasted my '93 XR 250. I took Bill's advise and used coal abrasive at 135 psi and after many sessions got all the paint off. I just want to say thanks to everyone and hope this useful information finds future bike enthusiasts that run into the same questions I had.

Break.
 
1 - 15 of 15 Posts
Top