Makita PLM4120 - User Manual

Questions and Answers

J
James PerezJul 30, 2025
What to do if my Makita Lawn Mower engine is hard to start or loses power?
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  Billy FigueroaJul 30, 2025
  If your Makita Lawn Mower engine is difficult to start or loses power, it could be due to several reasons. The fuel tank might contain dirt, water, or stale fuel; in this case, drain the fuel, clean the tank, and fill it with clean, fresh fuel. Also, the vent hole in the fuel tank cap could be plugged, so try cleaning or replacing the fuel tank cap. A dirty air cleaner element can also cause these issues, so clean the air cleaner element.
I
ithompsonAug 8, 2025
Why is my Makita Lawn Mower engine overheating?
- R
  rmooreAug 8, 2025
  If your Makita Lawn Mower engine is overheating, it might be due to restricted cooling airflow. Remove any debris from the slots in the shroud, blower housing, and air passages to ensure proper ventilation. Another possible cause is an incorrect spark plug. For the PLM4120 model, install an RC12YC spark plug and ensure the cooling fins are on the engine. For the PLM4620 model, use an RJ19LMC spark plug and cooling fins.
E
Emily ShawAug 12, 2025
Why does my Makita PLM4120 vibrate abnormally?
- M
  Melissa StevensAug 13, 2025
  If your Makita Lawn Mower vibrates abnormally, it could be due to a loose cutting assembly. Try tightening the blade. Alternatively, the cutting assembly might be unbalanced, so try balancing the blade.
K
khooverAug 17, 2025
What causes a Makita Lawn Mower engine to operate erratically?
- E
  elizabethgonzalezAug 17, 2025
  If your Makita Lawn Mower engine operates erratically, it could be due to a defective spark plug. You should install a new, correctly gapped plug. Another possible cause is an incorrect spark plug gap; set the gap between the electrodes at 0.7 to 0.8 mm. A dirty air cleaner element can also cause this issue.
T
Timothy KentAug 21, 2025
How to fix a Makita PLM4120 engine that idles poorly?
- A
  Alvin AbbottAug 21, 2025
  If your Makita Lawn Mower engine idles poorly, it could be due to a dirty air cleaner element. Also, air slots in the engine shroud might be blocked, so remove any debris from the slots. Additionally, cooling fins and air passages under the engine blower housing could be blocked; remove any debris from these areas.
B
Brian Carey Jr.Aug 26, 2025
Why does my Makita PLM4120 Lawn Mower engine skip at high speed?
- A
  April LamAug 26, 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.
D
Dustin HudsonNov 3, 2025
How to troubleshoot a Makita PLM4120 Lawn Mower when the engine does not start?
- B
  Barbara DeleonNov 3, 2025
  If your Makita Lawn Mower engine doesn't start, there could be several reasons. The throttle choke might not be in the correct position, so try adjusting it. The fuel tank could be empty, so you should fill it. A dirty air cleaner element can also prevent starting, so clean it. Check if the spark plug is loose and tighten it to 25 - 30 Nm if necessary. Ensure the spark plug wire is properly connected. The spark plug gap might be incorrect; set it between 0.7 to 0.8 mm. The spark plug itself could be defective, in which case you should install a new one. If the carburetor is flooded with fuel, remove the air cleaner element and pull the starter rope until the carburetor clears itself, then reinstall the air cleaner element. If none of these solutions work, the ignition module may be faulty,...

Summary

SYMBOLS MARKED ON THE PRODUCT

GENERAL SAFETY RULES

Training

Instructions for proper use and familiarization with controls.

Preparation

Guidance on protective clothing and site inspection.

PARTS DESCRIPTION

TECHNICAL DATA

ASSEMBLY

ASSEMBLING THE FOLDING HANDLE

Fixing the lower and upper handlebars to the unit body.

ASSEMBLING THE GRASS CATCHER

Steps for fitting and removing the grass catcher.

STARTER HANDLE

Procedure for moving the starter handle to the rope guide.

HEIGHT OF CUT

Instructions for adjusting the cutting height lever.

ADJUSTMENT FOR AN APPROPRIATE HEIGHT

2 IN 1

What is Mulching?

Explanation of the mulching process and its benefits.

Retrofitting for Mulching Mower

Guide to convert the mower for mulching function.

OPERATING INSTRUCTIONS

BEFORE STARTING

Instructions for engine servicing with fuel and oil.

TO START ENGINE AND ENGAGE BLADE

Procedure for starting the engine and engaging the blade.

OPERATION PROCEDURES

Guidelines for holding the stop control handle during operation.

TO STOP ENGINE

Steps to safely stop the engine and blade.

FOR THE BEST RESULTS WHEN MOWING

Tips for optimal mowing performance and grass dispersal.

GRASS CATCHER

Instructions for emptying and cleaning the grass catcher.

DECK

Advice on cleaning the underside of the mower deck.

HEIGHT ADJUSTMENT INSTRUCTIONS

Procedure for adjusting the cutting height using the central lever.

MAINTENANCE INSTRUCTIONS

SPARK PLUG

Recommendations for spark plug replacement and servicing.

LUBRICATION INSTRUCTIONS

Guidance on lubricating wheels, engine, and stop control.

CLEANING

Instructions for cleaning the mower and engine air cleaner.

ENGINE AIR CLEANER

Procedure for cleaning the engine air filter element.

CUTTING BLADE

Safety precautions and steps for working on the cutting blade.

BLADE MOUNTING TORQUE

Specifications for tightening the blade mounting bolt.

ENGINE

Reference to engine manual for maintenance and service.

STORAGE INSTRUCTIONS (OFF SEASON)

TROUBLE SHOOTING

ENVIRONMENT

Makita PLM4120 Specifications

General

Type	Push lawn mower
Cutting width	410 mm
Grass catcher	Yes
Cutting system	-
Number of wheels	4 wheel(s)
Recommended lawn area	1000 m²
Maximum cutting height	75 mm
Minimum cutting height	20 mm
Grass collecting volume	50 L
Cutting clearance adjustment	5
Motor power	2.8 hp
Power source	Gasoline