How To Repair Plastic Part 2

[Bubba Zanetti]

How to Repair Motorcycle Plastic Part 2

Before you read through part 2, I highly recommend you read or re-read Part 1. The same surface prep, cleaning and general information applies. I will explain this information again, but it may be abbreviated in nature.

Let’s fix some ABS plastic!

Part 1 focused on smaller cracks and repairs along with strengthening the front of a larger repair.

Part 2 will focus on the LARGE repair such as a fairing that has been broken almost in half or in half, but is missing no major pieces. Thus, you can take the fairing and put it back together like a puzzle piece.

You will need similar tools as before to complete the project:

80 grit sand paper
Quart of Acetone
Clean cotton rags
Plastic Repair product (Bondo-Hair)
Applicator to apply product (Icing spatula)
A good motorcycling friend or understanding spouse/ girlfriend

The product I am using for this repair is available everywhere, is inexpensive and relatively easy to use! Its Bondo’s Fiberglass body filler or “Kitty hair” as some on the street call it since it looks like a cat hairball. It is a two part product and again you will need to follow the MIXING DIRECTIONS ON THE CAN!

The Bondo kitty hair is a good choice for repairs when you can remove the whole piece of plastic and the area the work is to be done is a large flat area ON THE BACKSIDE that will not be close to brackets or mounting hardware. The reason is the kitty hair needs to be built up in layers and you have to cover a large area for the product to grab and have enough strength to be durable and if you use it on the front of a fairing it will look like crap. Use this product in areas where it will not be visible! A good pre-preparation idea is to take the piece and hold it in place as best you can and see if any wires, hardware, etc. allow for very little wiggle room if the gap where the crack is located is filled with bonding product.

So you’ve determined nothing is even close to the fairing’s backside and the kitty hair fits your price range. Let’s begin!

As before, with a little modification, follow these prep steps!

1. Thoroughly wash the fairing on both sides removing any grease and road grime, and then dry the piece or pieces.

2. On the BACKSIDE of the piece take the 80 grit sand paper and sand at least four inches on both sides of the crack until the paint finish is gone and bare plastic is exposed. It doesn’t have to be sanded to death, just well sanded to bare plastic. And do this outside because it makes a mess.

3. Once the sanding is done, wash the dust off the piece and DRY THE PIECE before work begins. (Tip: You may think the piece is dry, but those scratches hold little bits of water you cannot feel. If you live in an environment or are doing the work on a rainy day in your garage. I recommend drying the piece with a clean towel as best you can then using a hair dryer on the sanded area. 5-10 minutes with the hair dryer should be plenty.

4. Get your application tools and product all together and grab that friend or spouse!


Put the fairings back together and get a feel for how they fit together properly, or better yet, if you need an assistant make sure THEY hold the prepped pieces together properly. (Note: I recommend waiting until after the project is done to have some beers).

Mix up some of the kitty hair and work with it on a surface you don’t care about to get a feel for how fast it sets up and how to work with it too! Watch me test mix on the mixing board I bought at Advanced Auto! (HINT: A nice piece of clean glass works well for mixing this product on!)

When the fairings are held together properly, mix up the Kitty hair and start applying it to the crack. Remember to spread it out like cake icing! Flatten the gob out and spread it and smooth it out! You want to build it up in layers on a flat area! The first couple layers may not be enough to hold the piece together, so make sure your assistant does not let go until the layers are thick enough to hold the piece. You’ll know because if they start to let go the kitty hairs start to make a snapping sound. In addition, kitty hair sets up very quickly (3-5 minutes average). Once one layer is set up (i.e. the product is hard to the touch) mix up another and apply it! As a general rule 3 or more layers is enough to hold the piece together. Once the repair is done you may notice the fairing does not flex as easily as before the repair. This is normal and also why you want to be careful not to build up the layers too much!

See the pictures at the end of part 1, that’s the kitty hair repair.

You also work in layers because it’s hard to get the product applied evenly on a large repair. The layer technique allows you to work the product over itself but also applying more in the areas where the fairing needs it!

Once you have enough product on the fairing and its set up, set the faring down and allow the kitty hair to finish it cure process. I recommend attaching the parts back to the bike the following day.

HINT: DO NOT try and mix up a huge batch of kitty hair and apply it all at once on a big repair. It will set up too fast and getting that crap off isn’t fun. Remember, layers, layers, layers! Try and make your layers a 1/8 of an inch at a time or 2-3 mm.

HINT: Kitty Hair grabs onto itself as long as the surface remains clean. So no sanding or anything is necessary between layers.

HINT: Wipe off your mixing surface and application tools with a clean cotton rag with acetone between mixings and applications.

HINT: You really need to mix the kitty hair and hardener together VERY WELL! Unfortunately, it’s not the easiest product to mix and once the products touch the hardening process begins. Sometimes a drop or two, and I mean drop(s), of acetone dripped onto the hardener and kitty hair, before you mix them can greatly help. However, this slows down the dry time a little bit and too much acetone will destroy the products integrity. This trick works well in hot dry weather too.

HINT: If you put too much kitty hair on, you can sand it back down once it’s dry. However, you’ll want an electric palm sander and you will be hating life. Sanding that stuff sucks!

As you can see from the two pictures I repaired the black plastic vent and two areas on the fairing. The fairing was cracked in two in the middle and the faring bolt had been smashed right out of the fairing! Nice thing was the piece fit right back in like a piece in a puzzle. You can also see how much product you need to get it to work too!

This was my original plastic repair so I don’t have as many pictures as I’d like. I never thought I would be trying to share this information on the web. In addition, kitty hair is not my favorite product to use because you often need to apply a fair amount to get it to the right strength to hold and you often need another person’s assistance. Depending of course on the piece being repaired and your work shop space and tools.

Don’t get me wrong, it works, but the Plast-Aid product I’ve used is so versatile and you don’t need as much product to get the same results. I’ve done some additional “strengthening” repairs since all this because the 4th gens plastics seem to crack for no apparent reason other than use. I also have learned a few other tricks like using plast-aid when its in its watery form like pouring it into the repair area and placing a piece of fiberglass screen into the product before it sets up. Great repair technique that works really well!

There you have it my plastic repair fiends!

Please feel free to PM me with questions.

BZ