Stens 131-039 PK2 Torch Spark Plugs F6RTC

What It Is

The Stens 131-039 PK2 is a two-pack of Torch F6RTC spark plugs designed for small engines in lawn mowers, tractors, and other outdoor power equipment. These are standard copper-core plugs intended for reliable ignition in four-stroke engines.

Fitment & Compatibility

Check your equipment’s owner’s manual or existing plug for the F6RTC designation. This plug has a 14mm thread diameter, 19mm (3/4") reach, and a 5/8" hex size. It replaces OEM plugs for many Briggs & Stratton, Honda, Kawasaki, Kohler, and Tecumseh engines (e.g., B&S 491055, Honda 98076-55877). Measure the thread reach and hex size on your current plug before purchasing—some engines use a longer or shorter reach. Verify the gap (usually 0.028-0.031") is correct for your engine; it may need adjustment out of the box.

Key Things to Know

• Quality: Stens is a reputable aftermarket brand for small-engine parts. These Torch plugs are an entry-level copper type—fine for standard usage, but not as durable as iridium or platinum.
• Installation difficulty: Easy. Use a 5/8" socket, hand-tighten until snug, then torque to 15-20 ft-lbs (or 1/4 turn past snug). Do not overtighten—strips aluminum cylinder heads easily.
• Common gotchas: The gap is pre-set but can vary; always check with a feeler gauge. These plugs are non-resistor type—if your engine requires resistor plugs (e.g., for electronic ignition), use a resistor version like F6RTC-R.
• Performance: Expect decent cold starts and steady idle, but copper cores wear faster (replace every 100 hours or annually). Not ideal for high-compression or high-RPM engines.

Should You Buy It

Buy this if you need a budget-friendly, direct replacement for a standard lawn mower engine and don’t mind annual swaps. It’s a solid value for older or lower-hour machines, but skip it if your engine requires resistor plugs or you want longer life from premium iridium plugs.