Paint Observations

[Wayne]

There were a few things I noted about 576 when i pulled the tank, sidecovers and air box. First, I saw that the paint on the bottom of the tank was dull, not glossy, like basecoat without clearcoat or even a colored primer. The air box was the same. Looked like just a coat of basecoat on the inside. Lastly, the sidecovers have nothing on the inside, just subsrate material.

So that begs the question, what has everyone been doing on their restorations? Paint inside out on covers and air box or as I found mine?  What paint technology was Honda using back then? If I didn't know better I would swear they used colored primer like we did in the NA automotive sector to save $$ on paint. That trick didn't come along for many years later though. I know to match the current House of Kolor is best, just curious on what was used back then.

[Wayne]

I think I answered my own question. I started stripping my air box to repair it and it is very apparent that the outside has a silver base coat with the candy red top coat. The inside of the box only has the top coat, no silver base. (probably to save money???) Since my original no indent 2 hole box won't be used when the bike is running I think I'll have the painter do it the same way.

I have read a few threads with respect to repairing these weathered old ABS parts. After a lot of research I have come up with what I hope will be a pretty sound repair procedure although it is very time consuming. I hope to have the first area repaired soon. I'll post some pictures once I complete the first  broken/damaged area.

[Steve Swan]

Very cool, Wayne !  Keep us posted of what you have learned and how you effect the repair.  I have never heard anyone discuss a decent repair for this old material.  If anyone can figure out a good repair, it is you.

[Wayne]

I wouldn't be handing out the credits yet Steve! I like my preliminary findings and tests I did on some pieces so I figured what the heck. Nothing ventured, nothing gained. Once I stripped my air box I found 2 types of body filler, fibreglass, pieces missing and lots of cracks. I have my work cut out for me to fix this thing! I could really use the lower area for #1 cylinder but if I have to I'll fabricate and mold a piece in. 

[Wayne]

Very cool, Wayne !  Keep us posted of what you have learned and how you effect the repair.  I have never heard anyone discuss a decent repair for this old material.  If anyone can figure out a good repair, it is you.

Steve, I have laid out the pocess thus far in my restoration thread. So far so good in my eyes!

http://cb750sandcastonly.com/smf_forum/index.php?topic=335.msg1859#msg1859

[Riccardo]

Hello to All,

-about repairing i've used the stain welder for repair the cracks and i saw that this material is very malleable when is hot, using (with high attemption)the stain welder i've fused other broken parts to mold and rebuild the male plugs that goes in the frame grommet;
-confirm for the rear side of the tank: no clearpaint, only base and candy paint, not third strate;
-about paint, i've noted that the parts in contact with fuel was clearcoated, the airbox was clearcoated and the covers not clearcoated, infact using the polish cream on the mine NOS c/b green covers i saw that the cotton begins light blue and this is the confirm that they was not covered by clear pain.

I think that this was the japanese school because i've seen the same clear paint on my Kawa Mach III tank,  while the covers are non clerpainted and the decals are free.

This is my experience about paint cearcoating.

Ciao

[Wayne]

Interesting observations Riccardo. Right along the lines of my findings on 576. So that begs the question, what is everyone doing when they paint their sandy? Does every surface get he clearcoat or are you following the original Honda template as outlined by Riccardo? Does it make a pinch of difference if the bike were being judged by a panel of experts?

I posted a bit about my air box repair in my restoration thread but the post seems to ave vanished. 

Anyway, here are a couple of pics of my repair thus far. The box is quite badly damaged and cracked, had two types of bodyfiller in it and fiberglass resin. I decided to do my repair with 100% ABS, no fillers, no adhesives just ABS. Liquefied ABS will come back to 75% of it's original strength so I figured that's a heck of a lot stronger than the old deteriorated crap in the existing unit. Here's where I am so far. It's starting to take shape and feels much stronger and solid already. I'll add more pic's when I get to the finish line.

[kettle738]

Riccardo's observation on clearcoat answered a question for me; my K0 1010369 (first UK spec CB750) is in blue green, all the plastic panels including the airbox are in very nice order, and I assumed they had been repainted.  The insides of each plastic part are a pale ivory white with no paint.

I had a mark on one of the side panels so I polished it out, and to my horror the cloth turned blue........no clear coat.  I stopped polishing real quick.  I was really puzzled at the time, how could a painter overlook clear coating both panels when everything else looked superb, I will take a better look at the insides of the panels.....what distinguishes a Honda panel from an after market one?

Second thing I agree with, this colour is notoriously hard to photograph, out of the hundred or so photos I have taken of this bike only one looks like reality and that is a close up with flash, all the others are way too blue.........strong sunlight makes a better job of it.

Mick.........kettle738

[Wayne]

For future reference here is the inside of the original 2 hole, no relief air box from 576. Note that it is just sprayed with the Red Candy paint, no primer, no clear.

This corner of the air box was completely smashed. I made a piece out of virgin ABS and grafted it in. Got the outside looking pretty good. I want to get the inside shaped as well. The trick will be retaining all those easter egg and round shaped molding imprints. 



It's shaped better on the corner than it looks in the photo. Pigments from sanding get into the acetone/abs mixture when brushing and they are impossible to get out. When all of the areas are repaired the plan is to give both the outside and inside some skin coats of the mixture to strengthen the box overall. It will be like painting it (slowly as to not melt the whole thing!) and then I will wet sand it to the final shape.