Will fiberglass fix holes in a Yamaha Motorcycle gas tank?

Answer 1

Some advice:

1. You MUST wear a respirator and use good ventilation when applying fiberglass resin. It's hugely toxic and will literally destroy brain cells if you're not careful.  And dust from the dry fibers will do to your lungs exactly what asbestos does.  Wear disposable latex gloves, since resin is an irritant and is sticky as h**l.  And little pieces of fiberglass fibers are extremely irritating to the skin and will make you itch like crazy. Safety glasses are a good idea too; if you get resin or fibers in your eyes, you'll be in pain for weeks, and may have permanent eye damage.

2. Wear clothes you don't care about when you 'glass your tank, since you'll probably ruin them.

3. Fiberglass comes in different configurations.  It's best to use cloth on flat areas and chopped roving on curved areas, since it conforms to curves easier than does cloth.

4. Mix up small amounts of resin; 1 oz. is about right for each layer.  Use a soft plastic container (like Tupperware, or a CLEAN margarine tub) and tongue depressors or clean popsicle sticks to mix with.  Make sure that the two resin parts are thoroughly mixed up.

5. The tank has to be absolutely dry and clean (no oil or grease -- even from your fingers) before fiberglassing it, or the fiberglass may not bond securely to the steel.  Once you've sanded the metal and removed all of the rust, wipe it down completely a few times with paper towels saturated with acetone.  Wear latex gloves, since acetone will mess up your skin, and is toxic.  And do this outside, since acetone fumes will kill you dead.

6. Cover the surface to be fiberglassed with mixed resin just before laying down the cloth or roving, then saturate the cloth or roving with resin from a loaded brush.  Coating the metal surface first helps it bond and makes it easier to apply.

7. Don't lay up one thick layer of fiberglass cloth or roving; build up 2, 3 or even 5 thin layers, allowing each previous layer to firm up first.

8. You may need to use a pair of scissors or a razor blade to cut slits on the edges of the cloth to help it lay flat against curving surfaces.

9. It's a LOT easier to trim off excess fiberglass and splops of resin before it's fully cured.  Use single-edge razor blades to cut away those things while the resin has the consistency of rubber, or you'll be grinding and sanding for hours after it's hard.

10. You MUST coat the interior of the tank with a top quality sealant.  The two best ones are from Bill Hirsch Auto ($30) and from Caswell Plating ($40).  If you don't do this, water that often contaminates gasoline will get between the layers of fiberglass and the steel tank, and can start rust pockets there which will soon destroy your work and may cause patches to fail.

Also, you should understand that there is some additional safety risk from using fiberglass to repair a tank.  This is because if you get in an accident and your tank is damaged, the fiberglassed areas of a fiberglass patched tank will crack more readily than an un-patched steel tank would.  So there's a chance that a crash that damages your tank could spill gasoline and cause a serious fire.  

Remember: err on the side of safety, not speed, cost or convenience.  You only get one life.