2-Pack 491055 Spark Plug for Champion RC12YC RC12YX 759-3336 BS 491055S 491055T 692051 72347 792015 805015 John Deere M78543 M87543 Kohler 25 132 12-S

What It Is

This is a 2-pack of standard copper-core spark plugs, direct replacements for Champion RC12YC and RC12YX. They’re designed for air-cooled small engines found in lawn tractors, zero-turns, and walk-behind mowers from John Deere, Kohler, Briggs & Stratton, and others.

Fitment & Compatibility

Before buying, check your engine’s spark plug gap spec (typically 0.030″ for most applications) and confirm the thread size is 14mm x 19mm reach — these are pre-gapped but should be verified. Cross-reference your OEM part number: this set replaces Briggs 491055, 491055S, 491055T, 692051, 72347, 792015, 805015; John Deere M78543, M87543; Kohler 25 132 12-S; and Champion RC12YC, RC12YX. Works with most Kohler Courage/Command, Briggs Intek/Vanguard, and John Deere 100/300 series engines. Not suitable for side-valve (flathead) engines or those requiring resistor-type plugs.

Key Things to Know

• Quality: Copper-core plugs are standard OEM spec for most small engines. They perform well but wear faster than iridium or platinum (replace annually or every 100 hours).
• Installation: Hand-tighten + 1/4 turn with a spark plug socket. Overtightening can strip aluminum cylinder heads. Use anti-seize compound sparingly.
• Common gotcha: Pre-gapped at 0.030″ but always double-check with a gap tool — shipping can knock it off. If your engine requires 0.025″ or 0.035″, adjust before installing.
• Two-pack value: At $7.50, this is essentially $3.75 per plug — cheaper than single Champion RC12YC at most hardware stores. Keep the spare in your tool kit.

Should You Buy It

If you need a reliable, budget-friendly replacement for a common small-engine spark plug and don’t mind annual swaps, this two-pack is a solid buy. It’s ideal for DIY mower owners with multiple engines or anyone wanting a spare on hand. Skip it if you need extended-life plugs (iridium) or have a high-compression engine that specifies resistor-type plugs.