Powerbuilt 14mm Back Tap Spark Plug Thread Repair Tool — Collapsible, ANSI 4118 Steel

Powerbuilt's 14mm Back Tap quickly repairs damaged spark plug threads by being inserted through the plug hole and re-cutting clean, usable threads as it's drawn upward.

If a spark plug thread in an engine is fouled, cross-threaded or partially stripped, the Powerbuilt 14mm Back Tap (model 640811) is built to restore the original thread form without removing cylinder heads or using traditional inserts. Its collapsible, patented design lets the tool pass into the combustion chamber and then expand so the threaded section re-cuts and extracts debris as you pull it up through the spark plug hole. Constructed from heat-treated 4118 steel and made to ANSI standards, this tool is intended for motorcycles, small engines and other applications that use 14mm spark plugs.

How does the collapsible back-tap design work?

The tool passes through the spark plug hole with its threaded flutes collapsed, then expands inside the chamber so the cutting threads engage the damaged cylinder head threads when pulled upward. This action both reforms threads and lifts metal shavings out of the bore, reducing the chance of debris falling into the cylinder.

• Collapsible body allows insertion through narrow spark plug openings
• Expands inside the chamber to engage and cut threads on the way out
• Pulling motion extracts debris rather than pushing it into the cylinder
• Patented geometry optimized for 14mm spark plug thread profiles

Will I need to remove the cylinder head to use this tool?

No — one key advantage is that the Back Tap repairs fouled or damaged threads without head removal, saving time and avoiding heavy disassembly. It’s intended to be used from the spark plug access point, which keeps the repair straightforward for routine maintenance and field repairs.

• Saves teardown time compared with head removal
• Designed for in-place repairs on motorcycles and small engines
• Reduces parts and labor cost vs. installing thread inserts
• Works in confined spaces where traditional taps can’t reach

What materials and standards ensure tool durability?

The 14mm Back Tap is manufactured from heat-treated 4118 steel for toughness and wear resistance. Production meets or exceeds ANSI standards so the thread geometry and strength conform to recognized criteria for thread repair tools.

• Heat-treated 4118 steel for long tool life
• ANSI-compliant dimensions and cutting profiles
• Patented mechanism tested for reliable expansion and retraction
• Suitable for repeated field repairs in workshop or roadside settings

How should I use the tool safely and effectively?

Insert the collapsed Back Tap through the spark plug hole into the chamber, then pull it upward while maintaining steady, controlled rotation to let the expanded threads reform the damaged cylinder head threads. Use proper PPE and follow standard engine cleaning to prevent accidental debris ingestion into the cylinder.

• Clean the spark plug bore before insertion to remove loose dirt
• Insert collapsed, rotate gently and pull upward to reform threads
• Inspect threads after use and apply anti-seize if appropriate
• Wear eye protection and follow engine manufacturer guidelines

Who is this for: The Powerbuilt 14mm Back Tap 640811 is aimed at mechanics, motorcycle enthusiasts, small-engine technicians and DIYers who need a fast, in-place solution for 14mm spark plug thread damage. It’s especially useful for field repairs, shops that handle frequent plug maintenance, or anyone avoiding expensive head removal and thread-insert procedures.