Chassis & Engine Polishing FAQ

It's easy to make that engine shine brighter than ever.

Pure aluminum is virtually inert; it corrodes very reluctantly. It is also very soft and weak, a poor material out of which to make motorcycle parts. But when alloyed with other metals, aluminum can be stronger than iron or mild steel. However, the same materials and chemical reactions that make aluminum strong also leave the resulting alloy very susceptible to corrosion. Motorcycle parts made of the most common and useful aluminum alloys swiftly resemble old TV antennas if they are not protected from atmospheric and chemical attack.
Japanese manufacturers have received some unfair criticism about the quality of their alloy parts. The aluminum alloys they use for the majority of engine and chassis parts corrode more rapidly and thoroughly than traditional alloys. You can buy an old Harley, Triumph or any other British bike and be confident that any aluminum corrosion can be removed and a superlative polish restored. Modern Japanese, and now Harley-Davidson, motorcycle alloy castings can corrode so badly they cannot be restored to their original luster. But while the older materials may resist corrosion more successfully, they are not as good at their basic task, strength, as the newer ones.

Yes, they are the same part. Before, the bike looked as if it had one wheel in the shredder, mostly due to its cases. Polish, paint and cleanup made the bike worth being seen on.

Gone is the old polish of a Triumph clutch cover or of the rocker boxes of a Shovelhead. Now we get less-expensive machine-polished cases covered with a clear plastic paint. Without the clear coating, today's polished cases wouldn't make it to the dealer without at least minor corrosion. As tough as these clear paints are, they do deteriorate with time, exposure to the sun and chemical attack. When they do, the owner can have an ugly mess to clean up.

Before we start to deal with correcting the consequences of case corrosion, let's take a lobk at what you can do to prevent the deterioration from occurring.

The tough clear coat the manufacturers apply to the polished cases of their bikes can be damaged in three main ways: exposure to the sun's light, chemicals and heat. If you intend to have any fun at all, you will put your bike in the sun and get its cases hot. If you live in Los Angeles or near the beach you will expose it to chemical attack. However, there is hope.

The easiest protection is to wash and wax the bike regularly. Washing removes chemicals such as salt that attack all the painted surfaces. The sun's energetic and harmful ultraviolet rays can be attenuated by generous coats of wax. Good old hard waxes such as Classic Car Wax and Slipstream are excellent examples. Wax also keeps the majority of the harsh chemicals, such as ocean salt, from reaching the fragile clear coat over the even more delicate surface of your bike's polished alloy cases. Just don't polish too much; you might rub right through the plastic coating in time.

I have seen numerous, rather new engines with yellowed clear coatings. Thiase engines had been run very hard and had other signs indicating they had gotten unusually hot. Low oil temperatures and moderate loads help keep the clear coating on engine case parts like new.

The restoration of polished and coated aluminum parts does not require special skills. Like many other mechanical tasks, this one is a matter of knowledge and confidence.

The information in this article is the result of much experience, both my own and that of helpful and interested enthusiasts. While the products and procedures discussed have proven themselves, they are not the only materials or methods that will do. The goal here is to share with you the knowledge that. a corroded case (or bike) is not lost and that you can restore it to its former sparkling condition.

Step 1: If you have the tools, confidence and a shop manual, I recommend that you work,with parts off the bike. Working with the pieces on the bench makes things go a bit easier. However, you can do a perfectly satisfactory job without touching a screw. By the way, you should remove the old paint outside in your driveway near a garden hose.

Commercial paint removers take off the remnants of the old clear coating. The OEM clear coat is tough, and you should buy a remover that attacks epoxy and modern automotive paints. I bought the can you see here at my local Standard Brands paint store. You should be able to get a powerful remover at any large hardware store; most will have several brands and the knowledge of which one is best for this application.

Be cautious: Paint remover can harm your skin and sight. Be sure to wear eye protection, rubber gloves and a long-sleeved shirt when you use paint remover - no kidding.

Clean the oil or grease off the part from which you are going to remove the paint. A rag and some solvent does nicely. Mask off any painted parts you wish to protect from the paint remover. Take care not to get the remover on any paint you want to retain.

With a one- or two-inch paintbrush, apply the paint remover, using a dabbing motion to get the remover into the crevices and to reduce the risk of slinging it all around your driveway. If you got a really powerful remover, the clear coating will immediately begin to bubble and lift from the surface of the metal. After a few minutes the remover will be spent, and you can wash it off with water and a stiff brush. There will probably be some spots of paint left in places; another application or two takes care of that.

Step 2: If the casting from which you have just removed the paint is extensively corroded, you will need more than Simichrome and a stout heart to straighten it out. A seriously corroded case can be wet-sanded with 400 or 600 wet-or-dry sandpaper and soapy water. However, before you decide to do this, you should make an attempt to polish the worst spot. You might be surprised at how bad the corrosion isn't.

Wet-sanding is very effective and can be successful - if you heed a couple of cautions. First, proceed slowly; don't try to use the sandpaper like a shovel. Move the paper with a circular motion and keep it wet with a water-and-soap solution. (The soap helps keep the paper from loading up.) Second, if the casting has become lumpy from the corrosion process, back the sandpaper with a wooden or hard-rubber block. If you don't do this, the finish will be wavy. Finally, do not let the sandpaper load up. If it becomes clogged, it leaves scratches that are too deep to polish out later.

Step 3: Modern mass-produced motorcycle parts are not polished; they are sanded with very fine sandpaper. You can beat the sheen of the original finish on the parts you restore.

There are many polishes on the market and many serve well. Those shown here-Mother's and Simichrome-as well as Blue Magic are my favorites. Mother's initially cuts very fast and then polishes with less effort than most others. Blue Magic can give an incredible mirrorlike surface with hand polishing. Be wary of any polish you have not tested; some have lumps in them that can deeply scratch the surface.

Heat is an essential part of polishing. Unless the aluminum becomes hot from the friction of rubbing it with a cloth loaded with polishing compound, it will never get really bright. When you apply. Mother's Mag Polish, Simichrome or Blue Magic to a very slightly damp cloth, do so sparingly. These and other similar polishing compounds have water in them, and most of that water must disappear before serious polishing takes place.

When you apply polish to the surface and start to rub it in (circular motions, please), the frictional heat evaporates the water. During this time the grains of abrasive are leveling the surface by removing the high spots. As the water disappears there is a dramatic rise in friction and temperature between the cloth and the surface being polished; you can feel this when it happens. That is the time to really lay on the effort. When heat and friction build, polishing starts. If you make the common mistake of adding polishing compound each time the last load begins to dry out and get hot, you will continue to grind away at the surface and never achieve a true polish.

You may want to take advantage of your drill motor and polish your bike's parts with a polishing wheel or disc. That's fine, but it is very easy to round corners and dig ditches in the surface this way, so I urge you to practice on some hard-to-see parts before you take on a clutch cover. I have used drill motors for polishing and prefer one of the woollike buffing discs instead of the traditional cloth wheel. The buffing disc is gentler and spreads the load over a greater area at any one time, making it more difficult to dig ditches in the finish.

You may find that the corrosion has penetrated into the casting far enough that polishing won't remove it. If that happens, there is little you can do. If the staining is bad, you might consider painting the part with silver case paint. Yamaha sells a silver aerosol paint that is compatible with its excellent clear overcoat. The Yamaha silver-clear combination is attractive and is the next-best finish to the original polish.

Step 4: The parts must be clean if you expect the new clear paint to stick. A freshly polished part has its surface impregnated with polishing compound and oily debris; that stuff is rather tenacious and some care is needed to ensure that it is all gone. Hot soapy water, a cloth and elbow grease seem to be the most successful combination. Use a soap like Formula 409, Fantastik or dissolved dishwasher detergent; these are powerful and won't damage the freshly polished surface. Dry the parts in the sun to get rid of all the water and to warm them slightly before you paint.

Step 5: I have searched many years for a satisfactory aerosol clear paint and have found a couple that are tough and a couple that are clear. The only one I know of that is both is sold by Yamaha as Clear Top Coat (PNT-65000-04-00). Before you go out and get something from the drug store, consider that many of us have tried a number of different paints and prefer this one.

Clear can be difficult to apply simply because it is hard to see as it goes on. If you can arrange a single light so it is reflected in the polished metal surface, you will be able to see the clear as you apply it and can then better control the painting. Also, there are no pigments to help hold it in place, so it tends to run easily. Practice on a part that isn't prominent. It certainly helps if you are shooting on a warm, dry day. The paint can should be somewhere near 70 degrees Fahrenheit and so should the parts.

Apply a very thin coat and let it sit for a couple of minutes. This coat will partially dry and then stick to both the metal and the next, thicker coat you lay on. If you spray with the spray head too close to the surface, the paint tends to bubble and run because it is too thick directly under the blast of the nozzle. I have found that the guys who write the instructions seem to know, and I follow their directions.

After the paint is dry enough that bugs won't stick to it, lay the parts in the sun to dry. If you have no sun, you can use an oven if you are very careful not to let the temperature get above about 200 degrees and the paint has had some time to dry first.

Cleaning up, polishing and repainting are the three basic steps. None of them is difficult; none requires years of experience. The most important part of the job is the belief that you can do it. That belief together with the knowledge gathered by other enthusiasts and presented here give you the tools needed.

Besides the satisfaction of doing something well, you will also have a much better looking bike. A good scrubbing, some touch-up and freshly polished and protected castings can make a scruffy bike into one to admire. Old paint just needs new paint.