Makita PLM4120N - User Manual

Questions and Answers

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Kevin HurstJul 27, 2025
What to do if my Makita PLM4120N engine does not start?
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  Angela DudleyJul 28, 2025
  If your Makita Lawn Mower engine doesn't start, make sure the throttle choke is correctly positioned. Other possible causes include an empty fuel tank (fill it, referring to the engine owner’s manual), a dirty air cleaner element (clean it, referring to the engine owner’s manual), a loose spark plug (tighten it to 25 - 30 Nm), a loose or disconnected spark plug wire (install it), an incorrect spark plug gap (set it to 0.7 to 0.8 mm), a defective spark plug (install a new, correctly gapped one, referring to the engine owner’s manual), or a carburetor flooded with fuel (remove the air cleaner element and pull the starter rope until it clears, then reinstall the element). If none of these work, the ignition module may be faulty.
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Denise HuberAug 1, 2025
Why is my Makita PLM4120N Lawn Mower engine difficult to start or loses power?
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  Patricia SantosAug 1, 2025
  If your Makita Lawn Mower engine is difficult to start or loses power, the issue might be due to dirt, water, or stale fuel in the tank. Drain the fuel, clean the tank, and refill it with clean, fresh fuel. Another possibility is a plugged vent hole in the fuel tank cap, which you should clean or replace. A dirty air cleaner element could also be the culprit, so clean it.
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Noah NewtonAug 5, 2025
Why is my Makita PLM4120N engine overheating?
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  Sandra CalhounAug 5, 2025
  If your Makita Lawn Mower engine is overheating, the cooling air flow might be restricted. Remove any debris from the slots in the shroud, blower housing, and air passages. Also, ensure you are using the correct spark plug and that the cooling fins are properly installed on the engine. Install original spark plug and cooling fins on engine.
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Oscar HernandezAug 10, 2025
What causes a Makita PLM4120N Lawn Mower engine to operate erratically?
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  Kristin LeeAug 10, 2025
  If your Makita Lawn Mower engine operates erratically, the spark plug may be defective. Install a new, correctly gapped plug, referring to the engine owner’s manual. Also, the spark plug gap may be incorrect; set the gap between the electrodes at 0.7 to 0.8 mm. Finally, the air cleaner element may be dirty, so clean it, referring to the engine owner’s manual.
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turnercraigAug 14, 2025
How to fix a Makita PLM4120N that idles poorly?
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  tleachAug 14, 2025
  If your Makita Lawn Mower engine idles poorly, the air cleaner element might be dirty; clean it, referring to the engine owner’s manual. Additionally, check if the air slots in the engine shroud are blocked and remove any debris. Also, clear any debris from the cooling fins and air passages under the engine blower housing.
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westsarahAug 18, 2025
What to do if my Makita PLM4120N Lawn Mower vibrates abnormally?
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  Alexandra MossAug 18, 2025
  If your Makita Lawn Mower vibrates abnormally, the cutting assembly might be loose, so tighten the blade. Alternatively, the cutting assembly could be unbalanced, in which case you should balance the blade.
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Kyle WuAug 22, 2025
Why does my Makita Lawn Mower engine skip at high speed?
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  Tracey GonzalezAug 22, 2025
  If your Makita Lawn Mower engine skips at high speed, the gap between the electrodes of the spark plug might be too close. Set the gap between the electrodes at 0.7 to 0.8 mm.

Summary

Symbols Marked on the Product

General Safety Rules

Assembly

Assembling the Folding Handle

Steps to assemble the folding handle structure.

Height of Cut Adjustment

2 in 1 Mowing Features

Operating Instructions

Before Starting Engine

Pre-operation checks and engine servicing before use.

Operating Instructions (Continued)

Start Engine and Engage Blade

Procedure for starting the engine and blade.

Operation Procedures

Stop Engine Procedure

Method for safely stopping the engine.

Maintenance Instructions

Cleaning

Cutting Blade Maintenance

Blade Mounting Torque

Storage Instructions (Off Season)

Troubleshooting

Makita PLM4120N Specifications

General

Type	Push lawn mower
Cutting width	410 mm
Grass catcher	Yes
Product color	Black, Blue, Grey
Uncertainty K	0.4 m/s²
Cutting system	Rotary blades
Number of wheels	4 wheel(s)
Sound power level	106.9 dB
Vibration emission	7.8 m/s²
Engine displacement	158 cm³
Sound pressure level	95.3 dB
Recommended lawn area	1000 m²
Maximum cutting height	75 mm
Minimum cutting height	20 mm
Grass collecting volume	50 L
Engine number of strokes	4
Cutting clearance adjustment	5
Cutting clearance adjustment type	Stepped
Power source	Gasoline