Most Honda lawn mower engines use a standard 14mm spark plug from NGK or Denso, commonly NGK BP5ES or BPR5ES (with equivalents from Denso). However, the exact plug can vary by model, so always check your mower’s model number and manual before purchasing.
Honda’s lawn mower lineup includes several engine families (such as GCV160, GCV190, GC, and GX variants). The right spark plug depends on the specific engine family, whether a resistor plug is required, and the correct heat range and gap. The following guide explains how to identify the proper plug and outlines common options you’ll encounter in the parts system for Honda lawn mowers.
Identify the right spark plug for your engine
To determine the exact plug, follow these steps. The steps assume you have access to your mower’s model number plate or manual.
- Find the engine family and model number on the mower (look on the engine shroud or data plate). Note whether you have a GCV, GC, or GX series engine.
- Inspect the old plug (if present) for markings and thread size. Most Honda small engines use a 14mm thread with about a 19mm reach.
- Determine whether your ignition system requires a resistor plug (often indicated by a suffix such as R in the part number, e.g., BPR5ES) or a non-resistor plug (_BP5ES_).
- Check the recommended heat range for your engine in the owner’s manual. Many Honda small engines use heat range 5 (e.g., BP5ES/BPR5ES), but some models may call for a 6 or another range.
- Set the correct electrode gap before installation. A typical gap for many Honda mowers is 0.030 inches (0.76 mm), but always confirm with your manual.
Concluding: By identifying the engine family, confirming resistor type, heat range, and the correct gap, you’ll select a plug that matches your Honda lawn mower’s requirements and helps ensure reliable starting and smooth operation.
Common plug options for Honda lawn mowers
These are the plug numbers you’ll commonly see recommended for Honda lawn mower engines. Always verify with your exact model via the manual or Honda’s parts lookup, as specifics can vary by engine family.
- NGK BP5ES or BPR5ES — 14mm thread, 19mm reach, resistor vs non-resistor variants; typical gap ~0.030 inches. Common for many GCV160/190 and GC engines.
- Denso W20EPR-U or W20EPR-U equivalents — widely used aftermarket substitute with matching specs (14mm thread, 19mm reach, 0.030" gap).
- Honda OEM spark plugs — Part numbers vary by model; use the engine’s official parts catalog or owner’s manual to confirm the exact Honda replacement plug.
Concluding: If you’re unsure, bring the mower model and, if possible, the old spark plug to a parts retailer or consult Honda’s official parts lookup. Matching the correct heat range, resistor type, thread size, and gap will help protect your engine and maintain performance.
Summary
For most Honda lawn mowers, you’ll typically use an NGK BP5ES or BPR5ES plug (with Denso W20EPR-U as a common equivalent), featuring a 14mm thread, 19mm reach, and a 0.030 inch gap. Always verify the exact specification for your engine model (GCV160/190, GC, GX, etc.) using the mower’s manual or Honda’s parts lookup to ensure compatibility and optimal performance.