Do It Yourself Tech Tips: Installing A Fuel Sight Gauge

Article By: Tyler Malinky

Originally Published In The March 2011 Issue Of Cycle Source Magazine


This article shows how easy it is to install a fuel sight gauge into the side of your gas tank. A sight gauge can be handy, especially if you have a small gas tank, for seeing when you are running low on gas. We show the installation on a new Sporty gas tank. If you are doing this mod on a gas tank that has had gas in it, please be sure that you clean it out thoroughly before welding so you don’t blow yourself up. We started with one of our own fuel sight gauge kits though there are many available on the market or if you have a lathe, you can make your own bungs.


The basic tools needed: drill, step bit (or you can use standard drill bits, but step bits, also called unibits, rule), center punch, cutting fluid and a marker.


First, figure where you want each bung and mark it on your tank, center punch the spot, and drill a pilot hole with a small drill bit. You can now use your step bit to drill the proper diameter hole (5/8” in the case of our bungs). The use of cutting fluid makes it drill easier and keeps from burning up your expensive bits. Once you have your holes, it is a good idea to work on getting out all the metal shavings from your tank with compressed air.



Clean any oil or dirt from the bungs and the gas tank in preparation for welding. The flanges on the sight glass bungs work well to keep the same stand-off height and make it easy to weld to the thinner sheet metal. Tack in place, and get to welding. Be careful to not overdo it with the heat and distort the threads in the bungs.



Here we go with the bungs welded in and ready to install the sight gauge kit. The bungs are 1/8” NPT as are the supplied chrome-plated brass elbow fittings. Simply thread the elbow fittings into the bungs; it is a good idea to use some thread sealant. I use Hylomar Universal Blue Racing Formula Gasketing & Sealing Compound. Dab a bit on the threads and you are golden.


By swiveling the fittings at different angles, you can get different looks, from a curved or S-shaped sight gauge to a straight one, in any color of fuel line you want.



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