Motorcycle Tank Repaint - Bondo, Primer, Decals, Pinstriping, Paint, Clear Coat

Part 1 The Prep: Bondo and Prime for Paint

I really couldn't find a concise, informative site that walked a guy through all the steps of repairing a motorcycle tank all the way from bondo to clear coat. So here is a process that seems to have worked for me. It has steps that were gleaned from multiple sites as well as a few friends and some buddies at Baxter Auto parts where I bought my House of Kolor rattle cans.

That's right, Rattle CANS! Sure, the catalyzed 2-part automotive paints that need to be pre-mixed and dropped into a paint sprayer are probably more durable, but I am not taking my motorcycle elk hunting so I think the finish will last. The Kandy from House of Kolor turned out real well straight from their rattle cans.

Here is the tank before I started. It is a tank from an 80's era GS550 Suzuki (so i was told by the junk yard). I just wanted to get rid of the tear drop style tank that came stock on the CB650 and this one gave me the cafe look I wanted. Since the CB650 was so short-lived in Honda's OHC line-up no one really makes any after market parts for it that bolt right on. This cafe project included quite a few custom mods and wasn't as easy as buying a CB750 like everyone else does. I knew what I was getting into but the power/weight ratio on the CB650 told me that the end result should be faster by comparison to the CB750.
Stock Specs 1982 CB650
Weight including oil, gas, etc.: 476.2 lbs.
HP: 63HP @ 9000 rpm
7.56 lbs per HP

Stock Specs 1982 CB750
Weight including oil, gas, etc.: 564.4 lbs
HP: 77HP @ 9000 RPM
7.33 lbs per HP

As you can see the 750 has a slight advantage, but when you look at the two bikes side by side with an eye for what can be removed, it is clear that the 650 has more weight to lose than the 750 in extra framing for the passenger pegs, centerstand, etc. Now that I have removed about 24 lbs worth of extra 80's Honda silliness (4 lbs in rear tail light assembly!) the numbers grow substantially.

Let's say I removed the same from both bikes (which I don't think could happen):
CB750
564.4 - 24 = 540.4 lbs
540.4/77hp = 7.01 lbs per horse

CB650
476.2 - 24 = 452.2 lbs
452.2/63hp = 7.17

Now the power to weight ratio is just about equal. Now add some horsepower to your equation with intake, exhaust and rejetting modifications and the CB650 will come out on top in the end. But like I said, it's too bad hardly anyone makes after market parts to bolt right onto the CB650.

While I am talking about modifications for speed I feel that too many home project bikes get short-changed by missing the one modification that can make all the difference in the world: The clutch disks. What good is any of the horsepower, especially the aftermarket increases made, if the power isn't getting to the final drive chain efficiently enough to be taken advantage of? You must get yourself a high performance aftermarket clutch assembly to transfer this power to the wheel or else your bike just looks and sounds cool, but like I said, gets short-changed by short-sightedness. (There I will now step down off the podium... for a bit anyway.)

Back to the tank:
It had some emblem mounting brackets and few dents that I needed to smooth out. So after a good bead blasting at my buddies place I slathered on the bondo hoping I had enough in the right places to bring it down to level. I mixed too much hardener (the little tube) in ratio to the actual putty and my dry time decreased substantially from the supposed 15 minute working time that the instructions told me I had. It doesn't take much to catalyze a good body filler.


So after bondo and sanding with 220 grit on an orbital sander, I primed it and sanded the inconsistent areas again with the orbital and then sanded some more with a large piece of 220 wrapped over a scrap of hardwood 2x4 to bring everything to the same plane across the flat areas.












































Then i primed it again and the result showed some minor inconsistencies... again. If you look closely at what appears to be a flat surface you can see an oval shadow that surrounds the area very lightly and another shadow right through the middle of that oval. These are the shadows that will destroy a good paint job in the end when the sun is hitting it. Get rid of them now. A good paint job is almost entirely in the prep.



Here is the aftermath of sanding that shows more clearly the areas that need more work.


Now here is the pro trick of this Prime/sand/prime step:
2 coats of primer in different colors

The raised spots shown on my tank above were so bad that sanding to "level" took it all the way back down to the bare metal. But in subsequent treatments of sanding, priming, sanding you will start to notice even the tiniest imperfections as you sand through the top primer color to the other primer color below.

*Some people might say that the level of detail work that I am talking about with the two coats of primer is overkill. But those people aren't allowed in my garage to drink my cheap beer.


***To help with wasting a bunch of primer though here is a trick I learned myself:***
After you sand and think you have a flat surface that is done and ready for the last coat of primer, wet the piece down with mineral spirits to clean it and then tilt it into a bright light and watch the reflection of that light on the surface. Look for the wavy distortion as the light does or does not reflect correctly around the curves or perfectly solid through the flat planes.




Plus after wiping it down I noticed a few more little spots that needed some help:


The above shots looked good but i was out of primer and still buzzing from aerosol cans so I decided to start mocking up the way I wanted the decals to look:




So the next day I had my lovely wife pick up some primer. Give your primer-runner the empty can so that you are sure to get the right stuff delivered. Primers might mix well and adhere to one another but it's not worth the risk.

And there we have it... Filled and primed like a professional... well the end result is but I bet the process is more efficient when done by a pro.





Part 2 The Paint: Applied Graphics Decals, Striping, Shimrins Base Coats, Metallic Paint and Clear Coat - all rattle cans by House of Kolor!

Most metallic paints require a specific undercoat which is basically a primer that is designed to reflect light back through the metallic paint correctly. I am going to use three different colored top coats white, black, and red in metallics. The black and white both use a white base coat so I planned my paint coats accordingly.

I have done the white base coat and then sprayed the metallic white top coat where I had mapped out the checkered decals. The decals are made by Applied Graphics and sold through reflectivedecals.com. They are retro-reflective which is a safety bonus since they are designed to shine the light back into the source. If you had headlights on and were sitting behind the wheel my checkers will light up in the night for you... cool. After applying the white top coat, and then decals, I taped off the areas I wanted to keep white in preparation for the black top coats.


Pulling the tape off of the black was sorta nerve racking. This was going to be the biggest part of whether my plan was going to work or not. Sidecovers... so far so good.


The whole tank looks pretty great...


... Except for one or two areas where I didn't push the tape down hard enough and I got some underspray. I used my fingernail on every raised edge of every decal and thought that I pushed down hard enough everywhere else but as you can see in the small bends it let a little black paint through.


Luckily the gas cap covers the worst areas. maybe I can tweak my red stripes to cover it up as well.





After black and white top coats were applied I sprayed on two coats of clear just in case I messed up the red striping and had to start sanding somewhere. Now in preparation for red and its base coat of silver, I taped everything off in a design that was painstakingly delicate. This time I pressed every miniscule piece of tape fragment down with the edges of my fingernails before I sprayed.




After carefully cutting the tape the way I wanted and pressing everything down I warmed up the tank by rigging my Wagner heat gun (which is good for only warming up your hands not stripping varnish or anything... but I picked it up for 2 bucks at a garage sale). It is pretty cold in my Oregon garage at night in February so I figured the paint would be happier if applied to a surface that wasn't "room temp". I also kept all my paint in the laundry room until I was ready to use it.


Hey Man, Silver would probably look good. Maybe I should stop here...


The silver base coat was VERY metallic. As I was spraying I could watch little flakes sputter out around the surface and glisten in my shop light. It was kinda romantic.


Well I went for the red top coat about 5 minutes after applying the silver and taking some pics with my camera phone. If you let the two layers dry together I think it helps them bond. (I forget which site I read that on, but it seems true).


After about 20 mins of drying I pulled the red tape job...


At first I was kinda disappointed. I couldn't tell what it was exactly. It could have been a number of things that were killing my perfectionist attitude and depressing the excitement over all the painstaking work I had done:
1) places where I had cut the tape actually showed black paint chipped off by the razor blade. That was a bummer.
2) there was still a bit of underspray or blow-under or whatever the tech-talk is for this. So now I had a bit of red on some of the white checker edge areas. You gotta click on this picture to see them on the right side of the right checker about in the middle of the tank.... still it totally bugs me.
3) The red looks kinda queer to me. Shoot. Maybe too much red, maybe too busy with all the striping. Crap. I don't know maybe it isn't too bad...


A few more minutes of carefully razoring edges of paint that wasn't quite right and small clean-ups here and there in small detail... maybe the red will look better under the clear coat.





After the above shots were taken I took a black and a red sharpie to the very small, 3-dimensional edges of the paint layers as well as where I had cut into the black with my razor blades. Now I know why a good pin-striper uses a special brush and pulls perfect lines without taping. Oh well all in all I think it worked pretty well and am pleased with the tank now that I cleaned up all the tiny areas that would have bugged me every time I got on the bike.

It is ready for the clear coat.