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Back to Riding Lawn Mower Comparison Last update:

What Causes a Riding Lawn Mower to Cut Uneven?

When mowing, a nice, even cut brings a crisp look to the yard. Evenly cut grass feels better to walk on and looks better. Sometimes the mower does not cut evenly though. In these cases, it's troubleshooting time. Set aside a day for this. Really. A lot can go wrong with a riding lawn mower. There are a multitude of possibilities to check to see why the mower does not cut evenly.

Cautions Before Working on the Mower

Working on any vehicle presents a danger. It involves working with electrical equipment. It involves working with sharp blades. Be careful. Follow these guidelines:

  • Turn off the mower. Remove the key from the ignition.
  • Disconnect the spark plug wire or the spark plug altogether.
  • Wear heavy leather work gloves.
  • Do not disable any protective features the manufacturer installed, especially the interlocks.
  • Replace all deflectors and guards when finished.
  • Read the owner's manual before beginning the maintenance.

The Multitude of Things It Could Be

lawn mower repairIf there's streaking present: Streaking occurs when the mower doesn't cut thin strips of grass. This usually occurs due to operator error or poor blade condition. If the owner lacks mechanical talents or doesn't feel comfortable conducting maintenance or repair work, many lawn mower repair businesses exist. A mechanic can conduct the work and the owner gets back a riding lawn mower in perfect condition.

The mower's design also can contribute to streaking and to step cutting which we'll cover in the next section. The design of the mower, especially its deck. To see if it is the problem, use a jack to raise a single rear wheel of the mower off of the ground just a little. A full, free-floating deck remains unaffected. Otherwise, the deck tilts. That tilt when one-wheel lifts higher causes the uneven cut. There’s no need to buy another mower that does have a free-floating deck. Simply slow down and make wider turns when overlapping cuts.

Otherwise, try these options:

  • Sharpen the mower blades.
  • Replace the blades if they have worn down too far.
  • Mow at full throttle because too slow engine speed results in uneven cuts.
  • Slow down to avoid hitting the ground too quickly which skips areas.
  • Clean out the mower because if the deck gets plugged up with grass, it will cut unevenly.
  • Overlap the cutting rows so the blades don't miss any grass.
  • Overlap more while turning because cutting width decreases during turning.

If there's stepped cutting present: Stepped cutting refers to sharp ridges remaining on the yard's surface. Mower deck damage, poor mower blades or blade maladjustment causes this.

Try these options:

  • Level the deck.
  • Check the tires for wear and proper inflation. Add air to the tires to fill them to the proper PSI.
  • Replace the blades if they have worn down too far.
  • Replace or repair a damaged deck shell.
  • Replace or repair the mower spindle if it is loose or bent.
  • Re-install the blades if they appear incorrectly installed.

If there's uneven cutting present: Uneven cutting refers to smooth or wavy troughs in the surface of the yard surface after mowing. The usual cause of this is damage or maladjustment of the mower deck.

Try these options:

  • Level the deck if it appears unlevel.
  • Replace or sharpen dull or worn blades.
  • Replace damaged blades.
  • Clean out the mower deck as it will cut unevenly if clogged up with grass clippings.
  • Repair or replace a damaged deck shell.
  • Replace or repair a loose or bent mower spindle.
  • The spindle may need replacement or repair.
  • Check that the blades have been correctly installed. If not, re-install them.

If there's scalping present: Scalping refers to the riding lawn mower deck grazing the ground or coming close to it. Scalping usually occurs due to mower deck maladjustment, unevenness in the topography of the lawn or the mowing at too high of speed which causes the mower deck to bounce.

Try these options:

  • Level or roll a bumpy or uneven lawn.
  • Raise the cutting height of the mower deck.
  • Slow down driving across the yard if the ground speed seems the problem.
  • Check that the deck is level. If not, level it.
  • Check the tire pressure. If it's uneven, inflate the tires.

mower leaves sparse patchesIf there's stingers present: The term stingers refers to when the mower leaves sparse patches of uncut grass. Operator error and lack of blade maintenance cause stingers.

Try these options:

  • Sharpen dull or nicked blades.
  • Replace blades that have worn down too far.
  • Mow at full throttle to avoid mowing too slowly. Conversely, mowing too quickly causes the same problem, so slow down.
  • Clean out the mower deck because if it's plugged up with grass, it can't cut properly.

Proper Cutting Technique

Many times, the operator error amounts to someone not used to using a riding lawn mower. Cutting an even row takes effort. It's an art. Topology affects mowing. Hills can be tough to master. Practice remaining at a right angle to the slope of the yard. If the riding lawn mower threatens to tip over, back down the hill and mow the lower valley or dip at an angle.

Disclosure: Some of the links in this post are 'affiliate links.' This means if you click on the link and purchase the item, I will receive an affiliate commission.
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