Walneck's Classic Cycle Trader - February 2008 - (Page 40)

SPECIAL FEATURE STORIES TIP OF THE MONTH ? Fix It Fer Good Detecting and Mending Fuel Tank Leaks by Mike Brown OK, we’ve found a serviceable used gas tank that meets the criteria set out the last time we talked tanks in the November issue of our prestigious publication. Now we want to paint it right? Well not just yet, we’ve got a bit of work to do before we even think about the primer coat. Why? Because there are a few feelings in Old Motorcycle Land worse than seeing a top-notch paint job ruined by a gas leak, sadly a very common occurrence, but one we can avoid entirely by pressure testing for leaks and then performing appropriate fixes. Although time deadlines forced the photo demonstration on a painted tank, it’s far better to strip a tank bare prior to testing. Sand or glass bead blasting works great but chemical strippers work too, but be very careful as the stripper’s chemistry has more harmful chemicals in it than Keith Richard’s body. Always chemically strip a tank in a well-ventilated room and use a chemical mask and gloves while working. It’s also important to remove as much rust as possible from inside of the tank before testing because we don’t want a stray piece of debris blocking what could be an exit hole for fuel. e of th side m in ption. le fro o ossib k is one as p e tan rust loose side of th in much ve as ly shaken remo orous re to ke su f chain vig o g, ma testin A section e Befor tank. Even if you don’t have a compressor, it’s very easy to rig up a means to pressure test an old Lots of pe tcock tank. First we need to introduce air into the tank, s allo w ea sy co and while a compressor is an ideal tool, and old nnec tion to an air so bicycle pump will work. All we need is a bit of air pressure urce as sh own. inside the tank, enough to force air out of any tiny holes that may exist. We did these tests at 20 psi, and less than that ought to work. Regardless, there is no need for high pressure that can destroy a tank. Contrary to popular rumor, you can’t pop dents with air pressure, but sure as an oil leak in an old Brit bike, you can distort and destroy a tank by introducing extreme pressure. The same goes for filling a tank with water and freezing it, another dent fix fable. With these myths dispelled, let’s turn our attention to the easiest way to introduce air into a tank, and that’s through a petcock. Most old Brits and many other petcock types conveniently have the same fitting as most air connectors, so it’s a simple process of hooking up an air line to the petcock. This will also tell if the petcock itself leaks. Odd ducks are easy to connect by simple use of fuel hose and clamps that will easily hold the pressures required, and many tank threads will mate with a male air connector. soap 0/50 ha5 e wit urfac tire s he en re. oat t ed, c ter mixtu uriz a press and w nk is he ta nce t O After rigging up the air source, be sure the other petcock is in the off position or that the hole is plugged. Of course, the gas cap must be on as well and will leak a bit as it’s supposed to vent, but this is ok and won’t affect the test. Keep the compressor running while testing to maintain constant but regulated pressure. 40 FEBRUARY 2008 I WALNECK’S CLASSIC CYCLE TRADER® I WALNECKS.COM http://WALNECKS.COM

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Walneck's Classic Cycle Trader - February 2008 Contents Message from Heidi Boe, General Manager American The Buzz w/Buzz Walneck 1954 Indian Brave 250 Biker Quiz Bench Racing w/Mark Zimmerman Fix It Fer Good - Tip of The Month Motorcylce Tips Events Listings & Advertisements Morries Place British Bonhams & Butterfields California Custom Culture Maria Barry - Biker of The Month 1972 Scott Flying Squirrel European 1984 Laverda RGS Corsa Japanese 1984 Honda 700 Nighthawk Competition Motorbikes & Scooters Memorabilia Parts, Accessories, Want Ads Antique Cycle Clubs How to Place a Word Ad How to Place a Photo Ad Area Code Directory How to Subscribe Let Us Help with Your Event

Walneck's Classic Cycle Trader - February 2008

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