Kubota Z421

Kubota Z421 Zero Turn Mower Review

The Kubota Z421 Zero Turn is a well-built semi-commercial mower. It is great for a part-time lawn care owner or homeowner with a large yard. This durable mower is easy to control and is capable of mowing a lot of grass, as you will see in this Kubota Z421 review.

While demoing this mower, I was surprised by the power and cut quality. The kawasaki engine, that is popular on many other mowers, offers plenty of power for some of the most demanding lawns. The cut quality of this mower was very good. It did a great job of dispersing clipping quickly and evenly.

The Kubota Z421 isn't the most comfortable mower on the market, but if you're looking for a simple mower that will last a long time and not break the bank, this is the mower for you. Let's take a look at some of the details.


The Kubota Z421 provides a Kawasaki engine that produces the torque necessary to go through the toughest lawns. The Z421 features an air-cooled two-cylinder gasoline engine that produces 24 horsepower.

The Z421 provides a slight boost over the 22 horsepower you'd get from the Z411, the other mower in the Kubota Z400 line. The engine also uses a key switch starter.

Kawasaki engine


The Kubota Z421 uses the Hydro-Gear Commercial ZT3600 transmission to move power from the Kawasaki engine to the wheels. The transmission helps the Z421 move at about 10 miles per hour.

You can control the speed with a two-hand lever, while the foot pedal helps you stop the mower.

You can push and release the locking pedal on the deck to raise it up and then use the dial to adjust the cutting height. Push and release the pedal once more to lower the deck again to cut at the height you prefer. The dial system lets you adjust the cutting height by quarter-inch increments.

The rear tire is 24 inches and features a low profile, while the front tire is 13 inches and features a smooth surface with a pneumatic control setup. The extensive footprint on the tires prevents ground compaction while also preventing turf damage when turning.

You've also got a massive fuel tank that can fit about 6.8 gallons. You could keep your mower going for about six hours before refueling, although that number depends on conditions. The tank also features a sight window to display how much fuel is left.

Z421 features

Cut Quality

You can order the Kubota Z421 with a 54 or 60-inch deck.

The Z421 features three blades that slice through each bit of grass in moments. The blades are angled to produce a clean cut that prevents stress on the grass. The blades also raise the grass to ensure they are trimmed right, even if the grass is long or slightly damp.

You can also adjust the cutting height from 1.5 to 5 inches with increments of 0.25 inches in between. The dial system allows you to adjust the cut height.

Cut Quality and blades


Kubota has put in enough effort in ensuring the Z421 stays active and functional through any cutting project. The mower features a five-inch-deep welded deck with a sturdy steel body. All steel parts are reinforced and bolted to provide a secure layout that won't buckle.

Kubota z421


The large low-profile rear tire on the Kubota Z421 mower provides enhanced traction while absorbing shocks on the ground. The zero-turn mechanism on the wheels also ensures the mower can move over grass without creating excess vibrations while turning.

The seat is soft and features a high back. The seat slides six inches forward and back for your comfort. It has armrests to keep you relaxed while mowing. The foot pan is also wide enough to handle an easy entry and exit from the mower. The controls are also ergonomically laid out on the right side for easy access.

Comfort Seat


The low profile on the Kubota Z421 makes it look appealing. The rollover protection structure at the top adds a quality look while also preventing significant rollover concerns. The structure also folds down for when you need to go under a low-clearance space or you need to store the mower in a compact area.

Aesthetics and rollover bar

Build Quality

The welded steel deck is one of the best parts of this mower, as it provides a sturdy body that stays functional. The cover over the engine has enough vents to allow hot air to move out and prevent overheating, but the design keeps the physical body secure to where outside items won't enter the engine.

Kubota Z421 Platform


The rollover protection system bar meets all ISO 21299 specifications to keep potential rollover situations under control. The foot pedal parking brake will keep the mower secure so it will not move until you are ready to start mowing. The key-based start and stop feature also prevent people from accidentally starting the mower.



The last part of this Kubota Z421 review to note involves the price of the mower. The 54-inch model is available for $7,227, while the 60-inch version is $7,770. Kubota provides various features to help people pay for their mowers, including a 0% down payment and no APR for 48 months. The offers Kubota provides for its mowers will vary.

Our Rating

Performance:4 out of 5 stars (4 / 5)
Cut Quality:4 out of 5 stars (4 / 5)
Durability:4 out of 5 stars (4 / 5)
Comfort:4 out of 5 stars (4 / 5)
Price:4 out of 5 stars (4 / 5)
Overall:4 out of 5 stars (4 / 5)

Wrapping It Up

This Kubota Z421 review shows that this zero-turn mower provides a quality ride and can help you cut through even the toughest spaces around your yard. It offers a comfortable ride while keeping you comfortable. You will enjoy how well the mower works when keeping the grass trimmed without potentially harming your yard.

Kubota Z421

Read also: Best Commercial Zero Turn Mowers

What do you think?

Do you have the Kubota Z421 zero turn mower? What do you think of it? Leave us a comment below. We would love to hear from you!

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For more information on this mower check out Kubota.

Images are from Kubota.

10 Replies to “Kubota Z421 Zero Turn Mower Review

  1. I purchased a Z721KW, 54″ cut, last year. It is an awesome machine with great speed, a nice cut and is supere comfortable and with one exception is an outstanding zero turn.
    I had a different machine for several years that did everything I wanted, but was a bit narrower cut and decided to upgrade to a Kubota.

    The one big problem I have is with traction. The Z721 does not do well on even mild slopes(sliding) and gets stuck very easily in very slightly muddy spots. Ordinarily, installing slightly more aggressive tires would be an easy fix…but the Z721 comes with 14 ” rims which is a bastard size and there is only ONE tire that is made for that specific sized rim and neither the dealership, Kubota or I can find a different sized rim or different tire that will fit the Z721.

    1. I wonder if you should be looking at automotive or recreational vehicle OFF-Road tires to get the “agressive”treaded tires you want, in the rim size you need.

  2. I have a z421 with the 60 inch deck and it is a great machine. I originally compared it to the Scag Patriot and it seemed that the Kubota was stronger built. One thing I considered was the overall simplicity of the mower. The fewer electronics, the fewer potential failures in the future. The only irritant that I have is that there is no fuel gauge; instead, Kubota has a sight window that makes it difficult to view the fuel level . A simple gauge would be much better. I did upgrade to a better seat, but the original seat was not bad at all. In fact, I kept the original seat and plan to install it on my 20+ year old compact tractor.

    I mow 3+ acres 1-2 times per week and the Kubota does an exceptional job. The mower powers through effortlessly even in the toughest and thickest St. Augustine grass. The cut quality is very good, as well.

  3. I have the 54″ Z421. I found the ride to be EXTREMELY rough. My previous zero turn had springs under the seat. This mower has nothing. I solved the problem by adding a suspension bracket under the seat. Problem solved. Unless your lawn is perfectly smooth you better plan on adding the suspension bracket.
    I can’t believe Kubota does not include this from the factory.

  4. I purchased the z421 in August of 2019 from a butler pa. Dealer and it worked great for the first 200 hours then the deck started falling apart. First a deck lift bracket broke and the dealer said they needed it for a month to fix it, so I fixed it myself ( simple weld) then at 202 hours the first spindle bearing went bad. The dealer told me since I fixed the arm myself I voided all warranties. No one stocks any parts so I had to pay over night shipping from kubota. Since first bearing went all bearings,bearing holders, blade shafts and belt pulleys have to be replaced every 200-250 hours. I am on my 3rd time right now changing all three spindle now at 650 hours. I have over 2000 in parts so far. I have contacted kubota and they said I have to deal with the dealer. I have found two other dealers that said they had the same issues with these mowers and they warrantied them and then had the customers trade them in for other unit. The power unit is good but deck is junk. Now this week the deck stud that holds the belt tensioner and pulley just ripped out of top of deck. I took the bearing to a bearing company and they said the bearing are made for table saw motors and can not get wet. Another dealer said the bearings can not be run for more than 2 hours or they over heat and the grease melts out. Going back to john deere and bad boy.

  5. I purchased the kubota z422 kwt -60. I have about 6 hours on the machine. My biggest complaint is the rear tires, I understand they use these to minimize damage to the lawn but they are dangerously useless. they slide and spin like crazy and often you cant stop or turn. The machine itself has been fantastic, even with the 60″ deck it cuts through tough thick grass. the suspension seat is really nice.

    Pros- kubota quality! heavy duty, cuts great. comfortable seat suspension, easy to use
    Cons- REAR TIRES are terrible!! No headlights. some sort of brush guard where the throttle is would be nice. Need to use the choke to start. residential style air filter.

  6. My Z421 has 238 hours. It has been in the shop three times to fix gas in the motor oil issue. I finally called the factory and they noted they would look into the issue. It has been two weeks and the dealer or the factory has not contacted me on the issue of this machine. Hope they fix it this time .

  7. We own one, along with a few actual commercial mowers. As alluded to elsewhere, the spindles are a serious weakness. The actual spindle shaft is a decent 25mm diameter, but the bearings seem to have a very finite 200 hour life. This alone disqualifies the unit from ‘ commercial’ designation if you ask me. The bearings used are China-sourced, branded by Peer – a reputable bearing source. They are supposedly engineered (https://www.peerbearing.com/pdf/peer_lawn_garden2012.pdf) with several features specifically for adverse conditions found in a turf application, but experience says those features fail to work. They are easy to change – you simply remove the nut holding the pulley and drop the blade shaft out the bottom. Unfortunately, the spindle housing is aluminum and can be wrecked easily if you run the machine with bad bearings. The real root of the problem is that there is no provision to grease the spindle. The bearings have a tiny amount of grease trapped inside when they are manufactured. Once that grease melts and escapes, they are deadmen walking. I may actually replace mine with sealed bearings, remove the inner side seal and install zerk fittings to allow filling the housing with grease. Otherwise, expect to pay $90 in parts for 6 new spindle bearings every 200 hours like clockwork.
    Other than that, the deck lift shaft on early models is prone to crack at the right front hanger (ours did in under 200 hours). I believe they released a beefed up shaft but it costs a couple hundred bucks; we made a weld repair. The seat suspension is a necessary add, and without it you sit too low in addition to the rough ride. The fuel ‘gauge’ is useless. Around here fuel is clear and the tank is slightly yellow. You cannot see the fuel level unless you really try. The deck hanger brackets on the 60″ are a bit weak. Ours bent at the left rear.
    All- in, this is a very respectable homeowner grade mower that has a couple of problems Kubota could fix. I would not suggest this for actual commercial use. Kubota markets this as ‘Pro-sumer’ level equipment which is probably accurate if they mean Joe Homeowner who feels good bragging to Jill Nextdoor that he has a ‘commercial’ ZeroTurn. Neither Joe nor Jill know the difference but Larry Lawnservice just shakes his head and laughs.
    We bought ours knowing it was hobby-grade but hoping it would prove more durable than the tin and plastic toys being marketed with other paint colors at the usual home centers and farm supply stores. The Hydrogear 3600’s are a fairly solid choice as transaxles go ( although transaxles in general are not ideal). The Kawasaki seems to be the only name still trustworthy in the class with Kohler and Briggs. The local Kubota dealer is excellent with part availability and prices there beat the internet sellers. Service is easy, though there is a serious lack of grease fittings ( NONE except the front wheels). The ROPS/seatbelt is a nice touch missing from lesser machines and the fold feature works well. The Kubota OCDC is pretty nice and I appreciate that they offer a factory engineered solution instead of forcing you to add an aftermarket or generic flap. The foot operated parking brake is great and the linkage is simple.
    Ultimately, for the price (which is now closer to $10k), you would be better off with a slightly used true pro-grade machine. The only people who should buy a NEW z421 are those who are incapable of doing their own maintenance and just want a shiny new orange toy with a WARRANTY to mow their little suburban patch. The irony is that if you actually need a 10mph 60″ deck, then you probably need something beefier than this unit. Spend the $10K on a real commercial mower that has seen a little use and it will probably last better than a new Z421, it just won’t be as pretty.

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