OEM Champion Spark Plug for Bad Boy 015-8000-00, 015800000 Lawn Mower Tractor Engine

What It Is

This is an OEM Champion spark plug designed as a direct replacement for Bad Boy mowers using part numbers 015-8000-00 or 015800000. It ignites the fuel-air mixture in the engine cylinder and is critical for starting, smooth idle, and full power output.

Fitment & Compatibility

Before buying, confirm your Bad Boy model uses the RJ19LM or equivalent Champion plug (this is the factory-specified plug). Check your owner’s manual or the existing plug’s side stamp for the exact number. This plug fits most Bad Boy zero-turn mowers with Kawasaki, Kohler, or Briggs & Stratton engines that call for a 14mm thread, 3/4” reach, and a gapped electrode (typically 0.030”). It is not universal—if your engine requires a different heat range or thread length (e.g., longer reach for some overhead valve engines), this plug won’t work. Measure the old plug’s thread length and diameter if unsure.

Key Things to Know

• Pre-gapped but verify: The plug is factory-gapped, but always check with a gap tool and adjust to 0.030” before installing. Rough handling can close the gap.
• Installation torque: Hand-tighten until snug, then add 1/4 to 1/2 turn with a spark plug socket. Over-tightening can crack the porcelain or strip threads.
• Anti-seize optional: Champion plugs have nickel-plated threads; anti-seize is not required and can cause over-torquing. If you use it, reduce torque by 20%.
• Common gotcha: Don’t use this plug if your Bad Boy uses a resistor-type plug (R prefix) and the old one was non-resistor, or vice versa—mismatch can cause radio interference or poor ignition.

Should You Buy It

If you have a Bad Boy mower that calls for the RJ19LM or equivalent Champion plug, this is the correct, reliable, and affordable OEM replacement. It’s ideal for routine annual replacement or troubleshooting a hard-starting or misfiring engine. For non-Bad Boy mowers or engines requiring a different heat range or thread size, skip it.