Painting and Sealing Motorcycle Fuel Tanks

painted motorcycle fuel tank

 70_musclecar_RT+6/Flickr/CC BY-SA 2.0

Of all the paint finishes on a motorcycle, the fuel tank is the one that most people will be drawn to. It is, after all, the most prominent item on a motorcycle. It goes without saying, therefore, that a good paint finish on a fuel tank is essential. However, as any professional painter will testify, applying the last coat of paint or clear lacquer is the easy part. 

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Preparing for Painting and Sealing

A) Halogen flood lights give both heat and light.B) It is important to protect the surrounding area when adding Red-Kote.C) Threaded mounting holes should be closed off with old bolts.D) The internal sealer has ran onto the outside finish on this tank. John H Glimmerveen Licensed to

In the case of a motorcycle restoration or in a situation where a fuel tank has received damage in an accident, the tank should be repaired and resealed on the inside first. Although sealing the inside of a fuel tank is very important, so too is sealing the outside, and although regular paint will seal the tank to an extent, there are other options.

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Powder Coating

A number of professional paint shops and motorcycle restoration specialists have started to powder coat the outside of motorcycle fuel tanks before any Bondo™ (filler) is used to fill any dents or marks. The advantage of powder coating a tank first is that the metal will be completely sealed from the environment. This will remain the case unless the painter uses too much sanding in a specific area and breaks through the coating. (Note: any threaded holes in the tank – see photograph 'C' – should have bolts placed into them to stop the buildup of powder.) 

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Etching Primers

Modern etching primers are available in aerosol cans and make for an excellent base coat prior to fillers. Ideally, the tank should have all of its original paint removed before applying the etching primer to ensure the primer sticks to the base metal of the tank and not some old paint that may be flaking off. (See note above regarding bolt holes).

When preparing a tank for painting, it will often take the painter a number of attempts to fill and sand flat any marks or dents. You should always re-prime the area with etching primer after each sanding session to seal it and also to check that the dent or mark has completely been dealt with.

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Safety Precautions

At all times when the painter is working on the tank, he or she should maintain a warm, low humidity environment which is well ventilated. In climates with harsh winters this is particularly challenging as it is relatively easy to warm an area but ventilating it at the same time is not easy (some jobs are best done during the summer months!). However, it must be remembered that many of the paints and tank sealing chemicals are dangerous to the respiratory system and basic masks from auto stores, for instance, are not sufficient for safe breathing in a poorly ventilated area--see workshop safety article. 

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Painting the Fuel Tank

In the photographs, the painter has used floodlights mounted on extendable arms. This system has a number of advantages including greatly increasing the light around the workpiece—the fuel tank in this case. As with all lights, this system gives off heat especially when halogen bulbs are used. Therefore the heat will help to elevate the temperature and also remove some latent humidity from the general area.

Having primed a fuel tank on the outside, it can then be sealed on the inside. There are a number of good quality motorcycle tank sealers on the market; however, it is imperative to follow the manufacturer’s instructions to achieve the desired results. The fuel tank in the photographs has been treated with a Red-Kote sealer which must be kept away from the outside of the tank in areas such as the filler or the threaded hole for the fuel tap—see photo ‘D’.

As with paints, the Red-Kote must be applied when the temperature range and humidity are within the manufacturer's recommendations.