Why Is My Scag Zero Turn Mower Cutting Speed Slow?

Deck Pitch and Level

• A Scag zero-turn riding mower's deck is adjusted for pitch and level prior to leaving the factory. Over time, a mower's pitch and level may need readjustment. If your mower's cutting deck pitch is too high or too low, then the blades may cut against the ground instead of the grass, which slows the blades. You can readjust the deck by manipulating the chain links according to the mower's operator’s manual.

Hardware

• The mower's blades are attached to the spindle shaft with flat washers, lock washers and a hex bolt. If any of that hardware is missing, rusted or otherwise damaged, it can interfere with the blades' cutting speed. Whenever you clean the cutting deck, examine the hardware and replace it if necessary. The spindle shaft may have rust or damage, too, and the blades may have rust or are dull, all of which can slow the mower's cutting speed.

Clog

• A clog in the cutting blades area also can affect cutting speed. If the mower cut a muddy or moist surface, then mud or grass clumps could be on a blade or the rotating shaft, which can slow down revolutions. A clog in the discharge chute assembly can prevent grass and other debris from exiting the blades' housing area, which would interfere with the blades' rotation. Check underneath the cutting deck frequently, and keep it relatively clean.

Belts

• The Scag zero-turn mower’s cutting deck rotates the blades through a belt-driven system. If the cutting deck belt becomes loose or very worn, it can lose traction on the pulleys and make blade rotation intermittent or slow. Also, a loose engine drive belt can reduce power delivered to the cutting deck. Check the belts after every two hours of mower operation for a new mower and after every 40 hours of mower operation thereafter. Also check the pulleys for damage.