Premium Steel Weld-In Petcock Bungs for Custom Motorcycle Fuel and Oil Tanks
TC Bros steel weld-in petcock bungs are essential components for custom motorcycle fuel tank and oil tank fabrication. These precision-manufactured NPT (National Pipe Thread) bungs provide secure, leak-proof mounting points for petcocks and tank fittings. Available in 1/4" and 3/8" NPT sizes to accommodate different petcock and fitting requirements.
Available Sizes:
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1/4" NPT - Standard size for many petcocks and oil tank fittings
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3/8" NPT - Larger size for higher flow applications and specific fittings
Key Features:
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NPT Tapered Threads - National Pipe Thread design creates leak-proof seal when tightened
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Premium American Steel - Made from 1018 cold rolled steel for easy, reliable welding
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Made in USA - Proudly manufactured in the United States
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Easy Installation - Inserts into 3/4" diameter hole and welds around 1" diameter flange
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Two Size Options - Choose 1/4" or 3/8" NPT to match your fittings
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Sold in Pairs - Each order includes two bungs
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Professional Quality - Precision-manufactured for consistent fitment and performance
Choosing the Right Size:
1/4" NPT: The 1/4" NPT size is the most common size for motorcycle fuel tank petcocks and oil tank fittings. This size works with standard petcocks and provides adequate flow for most applications. If you're replacing an existing petcock or using a standard aftermarket petcock, 1/4" NPT is likely the correct size.
3/8" NPT: The 3/8" NPT size offers a larger opening for higher flow applications or when using specific fittings that require the larger thread size. This size is ideal for custom applications, larger displacement engines, or when maximum fuel flow is desired. Always verify your petcock or fitting thread size before ordering.
Understanding NPT Threads:
NPT (National Pipe Thread) threads are tapered, meaning the diameter gradually decreases along the length of the threads. This tapered design is critical for creating a leak-proof seal. As you tighten an NPT fitting into an NPT bung, the tapered threads wedge together, creating a tight, sealed connection.
Important: NPT threads are ONLY designed to be used with corresponding NPT threaded fittings or pipe. Do not attempt to use standard bolts, machine screws, or non-NPT hardware with these bungs, as they will not seal properly and may leak.
Specifications:
- Material: 1018 Cold Rolled Steel
- Thread Types: 1/4" NPT or 3/8" NPT (tapered)
- Installation Hole: 3/4" diameter
- Flange Diameter: 1" (weld around flange)
- Quantity: Sold in pairs (2 bungs per order)
- Made in: USA
Common Applications:
- Fuel tank petcock mounting
- Oil tank fittings and bungs
- Custom gas tank fabrication
- Tank restoration and repair
- Custom chopper and bobber builds
- Cafe racer fuel tank modifications
- Oil tank construction
- Auxiliary fuel tank installations
Installation Instructions:
Proper installation is critical for leak-free performance:
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Mark Location: Carefully mark the desired location for your petcock or fitting on the tank
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Drill Hole: Drill a 3/4" diameter hole at the marked location
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Test Fit: Insert the bung through the hole to verify fitment
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Position Bung: Position the bung with the flange on the outside of the tank
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Tack Weld: Tack weld the bung in place, checking alignment
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Final Weld: Weld completely around the 1" diameter flange
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Clean Welds: Grind and finish welds as desired
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Pressure Test: Always pressure test your tank after welding to verify no leaks
Safety and Installation Notes:
- Always drain and purge fuel tanks completely before welding
- Never weld on a tank that has contained fuel without proper purging
- Use appropriate welding techniques for thin tank material
- Verify petcock or fitting thread size before ordering (1/4" or 3/8" NPT)
- Apply thread sealant or Teflon tape to NPT fittings when installing
- Pressure test all tanks after welding before use
- Professional installation recommended if not experienced with tank welding
Safety Warning: Welding on fuel tanks is extremely dangerous if not done properly. Fuel vapors can ignite or explode. Only qualified professionals should weld on fuel tanks. Always follow proper safety procedures including complete fuel drainage, tank purging, and ventilation.
Each pair of TC Bros steel weld-in petcock bungs is precision-manufactured from premium American 1018 cold rolled steel to ensure reliable welding, proper thread engagement, and leak-free performance for your custom motorcycle fuel or oil tank.
