How to Use J-B Weld on a Motorcycle Gas Tank That Leaks

by Joel Parks
section of car image by pixelcarpenter from

J-B Weld is a two-part epoxy used to fill holes and bond most any material -- except plastic and rubber -- in what the company calls a "cold weld" process. This means that unlike a traditional weld where extreme heat is applied, J-B Weld achieves the same strength chemically, with no heat. Think of it as a special glue that begins to set when mixed together, and is "cured" in in 4 to 6 hours, or overnight. J-B Weld forms a metal surface that can withstand temperatures up to 500 degrees Fahrenheit, and the product is not affected by gasoline, which makes it a popular product for repairing metal fuel tank leaks.

Step 1

Mark the leak with a felt-tip pen.

Mark the area of the gas tank where the leak occurs, using a felt-tip pen or a piece of tape.

Step 2

Remove the fuel line from the carburetor by gently pulling up on it with your fingers. If a hose clamp is present, loosen the clamp first with a flat-blade screwdriver.

Step 3

Insert the open end of the line into a spare gas can.

Step 4

Open the fuel tap on the motorcycle gas tank by turning the lever to the "on" position, and let all the fuel drain into the can. The location of the fuel tap varies, but it will always be at the opposite end of the fuel line you have removed.

Step 5

Rough up, or scratch, the metal surface around the leak with fine sandpaper. This will allow the J-B Weld to form a better bond. The surface to be welded should be free of dirt, oil , rust and paint.

Step 6

Clean the surface to be welded with acetone or lacquer thinner on a shop rag.

Step 7

Squeeze equal amounts of J-B Weld hardener and resin onto a piece of tinfoil.

Step 8

Use a putty knife to mix the J-B Weld.

Mix the resin and hardener together using a putty knife or small wooden paddle.

Step 9

Spread a bead of the mixed J-B Weld over the crack or hole in the tank, using the putty knife or paddle to smooth the repaired area.

Step 10

Allow to dry overnight.

Reconnect the fuel line to the carburetor and refill the tank with gas.


  • J-B Weld will set faster in an area where the temperature is 50 degrees Fahrenheit or higher. Use a light bulb or heat lamp to speed drying. The weld will be dark gray when it hardens, at which point it can be filed, smoothed with sandpaper and painted.


  • J-B Weld is nontoxic, but don't get it on your skin or in your eyes.

Items you will need

  • Felt tip pen or masking tape
  • Flat-blade screwdriver
  • Spare gas can
  • Fine grit sandpaper
  • Acetone or lacquer thinner
  • Shop rag
  • Tube of J-B Weld resin
  • Tube of J-B Weld hardener
  • Putty knife or small wooden paddle
  • Tinfoil
  • Light fixture or heat lamp

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