1 A grinder or sander for anything large. On this job I’m using an electric grinder fitted with a paint stripping wheel, a six inch bondo dual action air sander, and a common household electric ¼ sheet sander. You can do it by hand if you have a lot of patience, but the grinder with stripping wheel brought all my damage on the sidecar to bare metal in under a minute.

2 Several grades of sandpaper from around 80 grit if the job is not gigantic, up to 220 or 400 for finish work. On a project like this I won’t go up any higher than 220 but on a good car hood I’d go to at least 400. When you use sandpaper on a sander it raises the effective grit a bit. We used to cut big Bondo jobs on the initial cut with 40 grit on an air dual action sander. These bikes are so small that I used 80 on the air dual action for the first cut. For the fine paper from 220 up use wet or dry paper.

3 A can of Bondo or similar filler.

4 A coffee can with plastic sealing lid.

5 A couple of plastic applicators.

6 Some Scotchbrite, both fine and course.

7 Lacquer thinner.

8 Some cardboard.

9 Masking tape.

10 A couple of cans of primer of different colors.

11 Sanding blocks (You can make them).

12 I like those new sponge sanders for curved surfaces but these are optional.

13 Possibly bendable rubber sanding blocks or shapeable blocks depending on the surface you are working on.

14 Tide or similar and a container.

15 Rubber gloves, a sanding mask and eye protection are good practice.

16 Don’t forget rags and newspaper of real masking paper to cover what you don’t want paint on.

Remove all trim.

On this job I have number of dents and damage I have straightened as much as possible before beginning. I will have to completely strip the fuel tank so we won’t go into that here.

1 First I have stripped the paint back on the damaged surfaces with the grinder fitted with stripping wheel. Try to feather the edges and go as far back as you will be applying filler.

2 If you have air blow away the dust, otherwise wipe it clean with an old towel.

3 Prepare your materials to be ready to apply Bondo and clean up. When this stuff gels it hardens fast and it is best to be ready.

Lay out your coffee can and pour in some lacquer thinner. A few inches on the bottom will do. Put a piece of Scotchbrite that you will use to clean your spreaders in the can. The lid keeps the thinner from evaporating and keeps dust out. Have a rag handy too for the last wipe off.

4 Use a piece of cardboard for your mixing surface. I use an old box so I can put my trash in after and I don’t have to clean it up. The guy who taught me used a piece of Corvette hood but had to clean it after each use.

5 Read the directions on the can. It is going to give you a length of hardener to mix with about a golf ball size of filler. Don’t mix more than a golf ball at first or you will waste a lot. A basic rule of thumb is about 2 ½ inch strip from the tube to a golf ball size from the can makes a hot or fast mixture. The heat of the day makes a difference to hardening too. Go short on the hardener to begin with and you will be happier.

6 Use a spreader or putty knife to get your golf ball size lump from the can and mix the hardener and filler on the cardboard. Mix until the color is consistent but work fast. I just use one spreader here to avoid cleaning another tool.

7 Apply a full layer to the areas you have cleaned don’t go too thick, maybe ¼ inch. Hopefully you aren’t filling more than that and if possible try to leave a bit extra sticking up to cut off. After applying all areas go around and try to final shape what you can before it hardens. Oops, used too much hardener and now you have a large lump left on the cardboard? That happens, get used to it.

8 Now while the filler is slightly hard some folks like to file it to shape with a body file. If you need to do this you probably used too much filler anyway.

9 Clean the spreaders quickly. Use your backup spreader (an old one is good for this) to scrape the filler off the first spreader. Then dip both in the thinner and use the Scotchbrite to clean the spreaders. Some folks leave the spreader in the thinner can but they tend to die quicker this way. I just wipe them with a rag and they are ready to go next time.

10 Now sand the first layer of filler down. I used the air Bondo DA for this which makes it a 20 second job.

11 Now clean off the dust and look at all the areas you missed. Time to fill them again or get a cup of coffee. Coffee won. After a trip to Starbucks on the red bike I applied a second layer of filler.

12 This layer starts to get close so work it more carefully. I used the electric quarter sheet sander to work the compound angles a bit more.

13 So now we are up to a third layer and getting pretty close. After the usual application and clean up I used a long sanding block to bring the area straight. That’s when I realized I have now made about the only straight line on this bike, Chang factory quality ain’t what it used to be I guess. To get the gentle curves I used hard sanding sponges.

14 Now we are up to the first layer of primer. I use light grey here as it reflects so I can see better. After it dries you will find several low spots to do a tiny bit of filler in. After leveling these the second layer of primer will look fairly good.

15 While sanding primer as soon as you see metal stop. It will show up in the final paint and it means you must add more filler to the surrounding area.

16 After you have gotten the area as smooth as possible add a light layer of dark primer and sand again. Odds are you will find dark primer in low spots you have to fill. You can often find low spots with your hand you can’t see with your eye.

17 Use a mixture of Tide and water to final sand. Go over the entire area you will paint with Tide and Scotchbrite to get a good surface for the paint to bite on.

Rinse carefully and if you are like me hope the wind does not come up just after you paint.