NGK 5728 BMR4A Resistor Spark Plug – M14 x 1.25 Replacement Small Engine & Lawn Equipment Ignition Component

Part Number: 5728
Category: NGK Lawn & Garden Equipment Engine Replacement Parts
Type: Replacement BMR4A Resistor Spark Plug

The NGK 5728 BMR4A Spark Plug is a replacement ignition component designed for compatible gasoline-powered small engines and outdoor power equipment. Featuring a 14mm thread diameter, 9.5mm thread reach, and 0.7mm electrode gap, this resistor-style spark plug provides the electrical spark needed for reliable engine combustion. Its copper-core construction helps dissipate heat, while the nickel-alloy electrodes support consistent ignition performance. The NGK BMR4A is suitable for select lawn and garden equipment, agricultural machinery, and other small-engine applications requiring this spark plug specification.

Product Specifications

• Part Number: 5728

• Brand: NGK

• Spark Plug Model: BMR4A

• Product Type: Resistor Spark Plug

• Component Type: Small Engine Ignition Component

• Thread Diameter: 14mm

• Thread Pitch: 1.25mm

• Thread Size: M14 x 1.25

• Thread Reach: 9.5mm (3/8")

• Hex Size: 19mm (3/4")

• Electrode Gap: 0.7mm (0.028")

• Heat Range: 4

• Resistor Type: Yes

• Center Electrode Core: Copper

• Electrode Material: Nickel Alloy

• Seat Type: Flat with Gasket

• Terminal Type: Removable Nut

• Compatible Equipment: Select Gasoline-Powered Small Engines

• Documented Applications: Select Honda BF2A Marine Engines & F200A Tillers

• Application: Engine Ignition System Maintenance

• Quantity: 1 Spark Plug

• Condition: New

Features & Benefits

• Genuine NGK 5728 BMR4A replacement spark plug

• Features M14 x 1.25 metric threads with a 9.5mm reach

• Equipped with a 0.7mm factory-specified electrode gap

• Resistor design helps reduce electrical interference

• Copper-core construction promotes effective heat dissipation

• Nickel-alloy electrodes provide dependable ignition performance

• Corrosion-resistant metal plating helps protect the plug

• Designed for compatible small-engine ignition systems

• Suitable for replacing worn, fouled, or damaged spark plugs

Applications

• Select Honda BF2A outboard engines

• Compatible Honda F200A tillers

• Small gasoline engine ignition systems

• Select lawn and garden equipment engines

• Compatible agricultural and utility engines

• Outdoor power equipment spark plug replacement

• Routine small-engine maintenance and tune-ups

• Equipment specifying NGK BMR4A or stock number 5728

Important Information

• Verify NGK part number 5728 / BMR4A before ordering.

• This listing includes one replacement spark plug.

• Features M14 x 1.25 threads, 9.5mm reach, and a 19mm hex.

• NGK specifies a 0.7mm (0.028") electrode gap.

• Features an NGK heat range of 4.

• Uses a flat gasket-style seat and resistor construction.

• Confirm compatibility using your engine model and manufacturer's recommended spark plug specifications.

• Not every lawn mower, tiller, or small engine uses the same spark plug.

• Do not substitute spark plugs with different thread sizes, reaches, or heat ranges without manufacturer approval.

• Verify the required electrode gap before installation.

• Inspect the spark plug wire and ignition components for damage.

• Clean debris from around the spark plug opening before removal.

• Install carefully to avoid cross-threading the cylinder head.

• Tighten according to the engine manufacturer's recommended torque.

• Shut off the engine and allow it to cool before servicing.