Exmark COMMERCIAL 21 - User Manual

Questions and Answers

K
Kerry JohnsonAug 20, 2025
How to fix an Exmark Lawn Mower that will not start?
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  Gregory AndersonAug 20, 2025
  If your Exmark Lawn Mower engine won't start, starts with difficulty, or stops running, several factors could be at play. Start by ensuring the fuel tank isn't empty and that the fuel shutoff valve is open. Check that the throttle lever is in the correct position, specifically the Choke position. Inspect the spark plug for faults and either clean, adjust, or replace it as needed. Finally, make sure the spark plug wire is securely connected.
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Rachel LeeAug 22, 2025
Why Exmark Lawn Mower engine will not start?
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  Benjamin ReedAug 22, 2025
  There are several reasons why your Exmark lawn mower engine might fail to start. It could be due to an empty fuel tank, so ensure you fill it. Check that the fuel shutoff valve is open. Make sure the throttle lever is in the correct position, like the Choke position. A faulty spark plug or a disconnected spark plug wire could also be the cause; in this case, clean, adjust, or replace the spark plug and check the spark plug wire connection. If there is dirt, water, or stale fuel in the fuel system, contact an Authorized Service Dealer.
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whaydenAug 25, 2025
Why is my Exmark COMMERCIAL 21 Lawn Mower difficult to pull backward?
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  ynorrisAug 25, 2025
  If it's difficult to pull your self-propelled Exmark Lawnmower rearward, push the mower forward to disengage the transmission, and then try pulling it rearward.
I
Ian MurphyAug 26, 2025
What to do if Exmark Lawn Mower engine loses power?
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  thompsonpeterAug 26, 2025
  If your Exmark lawn mower engine loses power, several factors could be responsible. A dirty air cleaner may restrict airflow, so clean or replace the air cleaner element. Low oil level in the crankcase can cause power loss, so add oil as needed. Check the fuel cap; if the vent hole is plugged, clean or replace it. Also, a dirty fuel filter can cause issues, so replace it. Cleaning the underside of the lawn mower deck may also help. If there is dirt, water, or stale fuel is in the fuel system, contact an Authorized Service Dealer.
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Corey MurphyAug 28, 2025
How to fix Exmark COMMERCIAL 21 Lawn Mower that runs rough?
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  Michelle PalmerAug 28, 2025
  If your Exmark lawn mower engine is running rough, start by ensuring the wire is connected to the spark plug. A faulty spark plug can also cause this issue, so clean, adjust, or replace it. Ensure the throttle lever is in the Fast position. If the air filter element is dirty and restricting airflow, clean the air filter pre-cleaner and/or replace the paper air filter.
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Christian SullivanAug 29, 2025
What causes Exmark COMMERCIAL 21 to vibrate excessively?
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  Robert KingAug 30, 2025
  Excessive vibration in your Exmark lawn mower can stem from several issues. The blade might be bent or out of balance, so balance it, and if bent, replace it. Check if the blade mounting bolt is loose and tighten it. Also, clean the underside of the lawn mower deck, as accumulated clippings and debris can cause vibration. Finally, ensure the engine mounting bolts are tightened.
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Timothy MartinAug 31, 2025
Why does my Exmark Lawn Mower engine lose power?
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  Christopher WaltonAug 31, 2025
  If your Exmark Lawn Mower engine is losing power, there are several things to check. First, examine the air cleaner and replace or clean the air cleaner element if it's dirty. Next, verify the oil level in the crankcase and add oil if it's low. Ensure the vent hole in the fuel cap isn't blocked by cleaning or replacing the cap. Replace the fuel filter if it's dirty. Lastly, clean any clippings and debris from the underside of the lawn mower deck.
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Ronald LeblancSep 2, 2025
What to do if the Exmark COMMERCIAL 21 discharge chute plugs?
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  Kimberly CuevasSep 2, 2025
  If your Exmark Lawn Mower discharge chute plugs, ensure the throttle lever is in the Fast position. Try raising the cutting height to avoid cutting too much grass in one pass, and if necessary, cut a second time at a lower height. Slow down your mowing speed, and ensure the grass is dry before mowing. Also, clean any clippings and debris from the underside of the lawn mower deck.
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watsonmarioSep 4, 2025
Why is my Exmark COMMERCIAL 21 Lawn Mower engine running rough?
- S
  sfordSep 4, 2025
  If your Exmark Lawn Mower engine is running rough, make sure the wire is connected to the spark plug. Clean, adjust, or replace the spark plug if it's faulty. Position the throttle lever to the Fast position. Clean the air filter pre-cleaner and/or replace the paper air filter if the air filter element is dirty.
K
Katrina CrosbySep 6, 2025
How to stop an Exmark COMMERCIAL 21 Lawn Mower from vibrating excessively?
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  lbrownSep 6, 2025
  If your Exmark Lawn Mower or its engine vibrates excessively, start by balancing the blade. If the blade is bent, replace it. Tighten the blade mounting bolt, and clean any clippings and debris from the underside of the lawn mower deck. Lastly, tighten the engine mounting bolts.

Summary

Safety

Safety Alert Symbol

Safe Operating Practices

Outlines essential practices for safe operation and operator training.

Operation

Slope Operation

Discusses safe mowing techniques and precautions when operating on slopes.

Pre-Start Procedures

Stopping the Engine

Provides step-by-step procedures for safely stopping the engine.

Adjusting the Cutting Height

Blade Control Bail

Describes the function of the blade control bail for safety and operation control.

Operating the Self-Propel Drive (Self-Propelled Units Only)

Details on controlling the mower's self-propel speed using the drive bail.

Checking the Blade Brake Clutch (Blade Brake Clutch Units Only)

Procedure to test the functionality of the Blade Brake Clutch system before use.

Safety and Instructional Decals

Specifications

Maintenance

Recommended Maintenance Schedule(s)

A comprehensive schedule of maintenance tasks based on service intervals.

Periodic Maintenance

Check for Loose Hardware

Service Air Filter (Kawasaki Units)

Change Engine Oil

Detailed steps for changing the engine oil to ensure proper lubrication and performance.

Check Spark Plugs

Emptying the Fuel Tank and Cleaning the Fuel Filter

Adjusting the Blade Brake Cable (Blade Brake Clutch Units Only)

Check Engine Oil Level

Steps to check the engine oil level before each use for proper lubrication.

Check the Blade Brake Clutch Bail Operation (Blade Brake Clutch Units Only)

Verifying the proper function of the BBC bail for safety compliance.

Service Air Filter (Honda Unit)

Adjusting the Self-Propel Drive (Self-Propelled Units Only)

How to adjust the self-propel drive cable for proper engagement and speed control.

Checking the Mower Blade

Procedure for inspecting the mower blade for sharpness, wear, and balance.

Cleaning

Clean Grass Build-Up Under Deck

Cleaning Under the Belt Cover (Self-Propelled Units Only)

Cleaning the Discharge Tunnel and Plug

Cleaning the Blade Brake Clutch Shield (Blade Brake Clutch Units Only)

Storage

Preparing the Fuel System

Preparing the Engine

Troubleshooting

Engine will not start, starts hard, or fails to keep running.

Common causes and solutions for engine starting problems.

Lawn mower does not self-propel. (Self-Propel Units Only)

Addressing issues related to the self-propel function not working correctly.

Engine loses power.

Possible reasons and fixes for reduced engine power.

Uneven cutting pattern.

Exmark COMMERCIAL 21 Specifications

General

Cutting Width	21 inches
Drive System	Self-Propelled
Blade Type	Single Blade
Cutting Height Adjustment	7 positions
Engine Type	4-Cycle
Fuel Type	Gasoline
Deck Material	Aluminum
Cutting Height	1.0 to 4.5 inches
Warranty	1 Year Commercial
Fuel Capacity	0.26 gallons