Products List
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Filler Cap and Bung
FCwB$25.75 - $29.75Filler Cap and Bung Filler Cap and bung these are most commonly used for oil tanks or any other fluid container such as an overflow tank that does not need to be vented. We make a vented version of these filler necks as well. 1.250 x 12 threaded bung... -
Filler Cap and Bung Vented
FCBV$31.75 - $36.50Vented Filler Cap & Bung Kit – 1.25"-12 Thread, Compact Design This vented filler cap and bung kit is a compact, functional solution for gas tanks, oil tanks, or any fluid container that requires internal venting. Built around our trusted,... -
Brass Filler Cap and Bung
BFCB$44.75 - $47.75Brass Filler Cap & Weld-In Bung – For Oil or Fluid Tanks Upgrade your custom build with this premium Brass Filler Cap and Bung Kit, ideal for use on oil tanks, overflow reservoirs, or any non-vented fluid container. This setup provides a clean,... -
Brass Filler Cap with Tall Bung
BTFCB$49.50 - $57.00Brass Filler Cap with Tall Weld-In Filler Neck – Vented or Non-Vented Add classic style and versatility to your custom build with this Brass Filler Cap and Tall Weld-In Filler Neck. Ideal for oil tanks, gas tanks, or any steel or aluminum fluid... -
Brass Vented / Filler Cap and Weld in Bung
BVF$52.00 - $55.00Brass Vented Filler Cap & Bung Kit – 1.25"-12 Thread Back by popular demand, we’re now offering a vented filler cap and bung kit featuring a solid brass cap. Built on the same trusted platform as our original design, this version combines... -
Oil Tank Bung Kit
OTBK$32.50 - $38.50This kit includes all threaded fittings needed for proper function of an oil tank. This kit contains three 1/8 NPT fittings for your oil lines (feed, vent, and return) it also contains a threaded filler cap and bung. All weld in parts are available in... -
Aluminum Filler Cap with Tall bung
ATFC$30.75 - $38.50Tall Weld-In Filler Neck with Aluminum Cap – Vented or Non-Vented This tall weld-in filler neck and aluminum cap kit offers added height and versatility over our standard filler bung setup. Designed for custom applications like oil tanks, gas... -
Brass Gas Cap OEM HD Tank
BGCOEM$69.95 - $139.90Brass Gas Cap – Fits Harley-Davidson Models from 1986 to Present Give your Harley-Davidson a custom look with our precision-crafted Brass Gas Cap. Designed to fit all HD models from 1986 to the present, this cap uses the OEM-style thread and O-ring... -
Brass Oil / Filler Cap
BOFC$33.00By popular demand we are now making a Brass version of our common Filler Cap. These can be used for oil tanks or any other fluid container that requires a non vented cap. These caps use the same standard bung we have made for years the 1 1/4 x 12 thread... -
Brass Vented / Filler Cap
BVFC$39.00By popular demand we are now making a Brass Vented version of our common Filler Cap and Bung Can be used for gas tanks oil tanks or any other fluid container. These caps use the same standard bung we have used for years so if you want to upgrade to a... -
Weld in Filler Bung
FB$14.50 - $17.50These are our weld in filler bungs, used with all of our vented and non vented caps. 1 1/4" x 12 thread 1 3/4" flange OD 1 1/2" stepped down OD Available in Mild Steel, Aluminum, or Stainless Steel Sold each -
Tall Filler Bung
TFB$13.75 - $14.75Tall Weld-In Filler Bung – 1.25"-12 Thread, Mild Steel This tall weld-in filler bung is a modified version of our popular flanged filler bungs, designed for builders who want a bit more height on their filler neck. With an overall height of 1.25",... -
Replacement Filler cap O-ring
oring$0.39This is a replacement O-ring for all of our vented and non vented filler caps. Made from fuel and oil resistant rubber for a long service life. -sold each for $0.39 -
OEM Gas Tank Bung
OEMGTB$14.00This is an OEM style weld in gas tank bung, the same one used on all of the later Harley Davidson Tanks. Permits the use of factory or the vast variety of aftermarket replacement gas caps on the market. The bung is made of mild steel and has the threads... -
1/8" male NPT Vent Fitting
BVENT18$2.49This is a 1/8" male NPT fitting with a brass screen/filter. We commonly use these for our filler caps to provide a vent but cut down on the amount of fluid seapage from having a vented hole in a fluid container. They are oil and fuel resistant for a long...
Filler Caps – Secure, Leak-Proof Solutions for Custom Motorcycle Builds
Bung King’s filler caps and weld-in bungs are CNC-machined in the USA from high-quality steel, stainless steel, and aluminum, designed to provide secure, leak-proof seals for fuel tanks, oil tanks, and other custom fluid containers. These weld-on caps and bungs are perfect for custom motorcycles, choppers, and hot rod builds, ensuring a clean, professional finish while protecting your tank’s contents from leaks or contaminants.
Our filler caps are available in aluminum or brass, offering a range of options to suit your build’s aesthetic. The weld-in bungs come in steel, stainless steel, and aluminum, providing a strong, reliable base for secure tank mounting. Whether you're fabricating a custom fuel tank or upgrading an existing one, Bung King’s filler caps and bungs provide the durability, function, and style your project needs.
Key Features:
CNC-machined from steel, stainless steel, or aluminum for durability
Filler caps available in aluminum or brass for a range of finishes
Weld-in bungs for secure tank mounting, available in steel, stainless steel, and aluminum
Leak-proof design for secure sealing on custom fluid containers
Ideal for custom motorcycles, choppers, hot rods, and other custom builds
Weld-ready for easy installation and professional results
Designed and manufactured in the USA for top-notch quality and precision
When you need a reliable and stylish sealing solution for your custom tanks, Bung King filler caps and weld-in bungs offer the perfect combination of function, style, and durability.
