Spark Plug Cross-Reference | Save 40-60% on Replacements

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⚡ Quick Answer:

Small-engine spark plugs split by physical reach, not just engine brand. Short-reach flathead engines (older Briggs push mowers) use NGK BR2LM / Champion RJ19LM. Long-reach OHV engines (most current Briggs, Kohler, Kawasaki, Honda) use NGK BCPR5ES, BPR4ES, or BPR6ES depending on brand — these are NOT interchangeable with each other despite looking similar. Always confirm reach before buying: a wrong-reach plug can thread in and even fire, then foul early or strike the piston.

⚠️ Correction notice: An earlier version of this guide misidentified several NGK cross-references, substituting automotive-style “BPR” plugs where the correct small-engine cross is a different NGK family (BR2LM, BCPR5ES). This page has been rebuilt with verified crosses, organized by physical reach rather than model number.

Cross-referencing a small-engine spark plug isn’t as simple as matching a model number to a “close enough” NGK plug — the automotive BPR-series and the small-engine BR/BCPR-series look similar but are genuinely different products. This guide organizes plugs by what actually determines fitment: reach (how far the plug threads into the cylinder), not engine brand or model name.

🔌 Why Reach Matters More Than Brand

Flathead (L-head) engines use a short-reach plug, roughly 3/8in (9mm) of thread. Overhead-valve (OHV) engines use a long-reach plug, roughly 3/4in (19mm) of thread.

Fit a long plug into a flathead and the electrode can strike the piston. Fit a short plug into an OHV engine and it seals and fires poorly. Threading in is not the same as being correct — always match reach first, brand second.

Short-Reach (Flathead / L-Head) Family

OEM Part #	Fits	NGK	Champion	Gap
Briggs 802592S (also sold as 5095, 796112, 796112S, 591868)	Older Briggs flathead push mowers, 3.5–6.5 HP including Quantum	BR2LM	RJ19LM	0.028–0.030in

These OEM numbers all resolve to the same physical plug family. Quantum engines can vary by Code Date — confirm your exact engine’s Model, Type and Code number before ordering.

Long-Reach (OHV) Family — By Brand

Brand / OEM Part #	Fits	NGK	Champion
Briggs 491055S (Intek, most current mowers)	12.5–22 HP OHV, Intek single, V-twin (2 plugs per engine), 550EX, 675EXi	BCPR5ES	RC12YC (larger V-twins sometimes RC14YC)
Kohler 12 132 02-S (Command/Courage)	Kohler Command and Courage single-cylinder engines	BCPR5ES	RC12YC
Kawasaki 92070-2097 / 92070-2107 / 92070-0017	FR, FS, FX series engines (zero-turns, riders)	BPR4ES	RN14YC
Honda 98079-56846	GX120, GX160, GX200, GX240, GX270, GX340, GX390	BPR6ES	RN9YC

Kohler Courage Twin (24 584 01-S) likely follows the same BCPR-family pattern as the Command/Courage single but hasn’t been independently confirmed — verify against your engine manual if you have a Courage Twin. Kawasaki and Honda NGK crosses are confirmed via genuine OEM factory-parts kits; Champion crosses are confirmed via dedicated manufacturer-parts listings, not generic multi-brand “fits” charts.

🔧 Verified Spark Plugs — Buy by Family, Not Brand Name:

NGK BR2LM — Short-Reach Flathead Family

Correct cross for older Briggs flathead engines (802592S, 5095, 796112, 591868)

View

NGK BCPR5ES — Long-Reach OHV Family (Briggs & Kohler)

Correct cross for Briggs Intek/OHV and Kohler Command/Courage engines

View

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Find Your Engine’s Exact Plug

Find the engine stamp — Model, Type, and Code numbers are stamped on the blower housing (the metal shroud over the engine), not the mower’s brand badge. The engine stamp always wins if it disagrees with the deck sticker or owner’s manual.

Confirm reach against your old plug — lay the new plug beside the old one before installing, or count threads. Don’t assume based on horsepower alone; two mowers with the same HP can carry different engines.

Verify the gap with a feeler gauge before installing, even on a new plug — shipping can shift a pre-set gap. Never re-gap platinum, iridium, or twin-tip plugs; their fine electrodes can be damaged by bending.

Hand-tighten, then a quarter turn with the socket. Most plugs use a 5/8in (16mm) socket; some older or larger plugs need 13/16in (20.6mm).

⚠️ Never use a car spark plug. Automotive plugs have the wrong reach and heat range for a small engine, and the wrong reach can cause internal damage.

Matching a small-engine spark plug is about reach first, brand second. Confirm your engine’s Model, Type and Code number, match the correct short- or long-reach family, and verify gap before installing. For more DIY guides visit TractorPartsCentral.com.

? Frequently Asked Questions

Is NGK BPR5ES the same as NGK BR2LM?

No. BPR5ES is a projected-tip automotive-style plug; BR2LM is a non-projected small-engine plug with a different reach and design. They are commonly confused because of similar-looking part numbers, but they are not interchangeable for small-engine applications.

Are all small-engine spark plugs interchangeable?

No. Plugs differ in reach, heat range, and gap. A plug that threads in can still run poorly, foul early, or in the worst case strike the piston if the reach is wrong. Match reach first, then brand and heat range.

My manual and engine sticker list different plugs — which is right?

Trust the engine’s stamped Model, Type and Code number over the deck sticker or owner’s manual. If a mower has had a replacement engine fitted, the deck badge and manual can both be wrong — the numbers stamped into the engine itself are the tie-breaker.

How often should I change a small-engine spark plug?

Once a year, or about every 100 hours, is cheap insurance for reliable starting. A worn or fouled plug is one of the first things to check on a hard-starting mower or tractor.

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