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Kubota Z421 Problems

Kubota Z421 Problems And Their Solutions

If you are a big driver, certain parts of the car may bother you. As the ride gets older, trouble can also occur. Today, I will talk about some of the most common problems with Kubota Z421 Problems and how to fix them.

which are as follows:

(1) Carburator Clogging

(2) Kubota Z421 Won’t Move

(3) Deck Engagement Power Loss

(4) Rollover Protective Structure Problem

(5) Hard Deck Removal

(6) The Engine won’t start

(7) Center Blade Pulley Problem

(8) The Engine is running rough

(9) Ignition Switch Problems

(10) Weak Pipe Line

(1) Problem 1: Carburator Clogging

If you don’t care for a machine well, the carburetor could get clogged in any device, not just the Kubota Z421. But because the Z421 pipeline isn’t as strong, carburetors tend to get clogged up a bit more often.

The particles get through when the pipe wears out and gets stuck in the carburetor.


You must ensure the fuel pipe stays intact and leaks soon. If that means replacing the whole fuel line, then do it. Fuel lines that are made well will last a long time.

And if you check the mower’s health by hand once a week, that is enough to keep it from giving you many problems.

(2) Problem 2: Kubota Z421 Won’t Move

A common problem with the Kubota Z421 is that it won’t move. Several things can cause this. However, the most likely reason is that the drive belt is broken.

If the drive belt on your mower is loose, torn, or cracked, it will stop the rims from turning. You will have to replace this same drive belt to fix this problem.

You might also be having trouble with your electricity. Hydro problems can be hard and expensive to fix, but you’re looking for serpentine belt springs in particular. If the tensioner spring comes loose, the mower will stop moving.

(3) Problem 3: Deck Engagement Power Loss

This often happens with zero-turn lawnmowers, but to be honest, it only happens sometimes with Kubota Z421 mowers when the deck is engaged.

And some of them have had a problem because they did things wrong. But here, I’ll list every possible reason why the mower might stop when the deck is engaged.

And will also try to offer a solution.


Too much dirt is a common cause of power loss at deck engagement. The air filters and cooling fins get clogged up with too much dirt.

And when the engine can’t get the air it needs and can’t cool down, it loses power. Sometimes dirt can also get into the fuel system. Also, the engine will stop if water gets into the fuel system.

So please keep a look out for these so you can check them. The second most common cause of power loss is not having enough oil.

The level of oil in the crankcase can cause this same engine to stop all of a sudden. Both the low as well as high crankcases need to have the right amount of oil.

If the oil is low, there won’t be so much oil left to lubricate the engine’s moving parts, which can cause the engine to lose power.

And if the petroleum level is very high, more air will get into the lubrication system, which will cause the engine to lose power.

The Kubota Z421 mower also might lose power when the deck is engaged if the muffler is clogged.

The muffler is where the vapors and gases from the burned gas can go. The car will lose power if the muffler gets clogged, which usually happens because of liquids, oil, and other debris.

(4) Problem 4: Rollover Protective Structure Problems

The rollover protective structure, or ROPS, is another problem that often happens with the Kubota Z421. The ROPS is a security measure that all ride-on lawnmowers must have by law.

With this feature, the mower won’t flip over if users hit a significant object or drive over a rough patch of ground. But the ROPS can get broken or even come off of the mower.

It’s important to know that several Kubota mowers, such as the Z421, have been recalled because the rollover protective framework can come loose, which is dangerous for people’s health.

(5) Problem 5: Hard Deck Removal

Getting cards off the deck throughout Kubota Z421 is hard. Kubota made it a little easier to get the deck off. But, as I said, this mower’s deck is a little hard to take off. It’s also a little distinct from other mowers.

Here’s how to take the deck out.


You first need to set the dial that controls the cutting height to 1 inch. Then do the same thing with anti-scalp rollers, setting it to 1 inch.

Now put a 0.55-inch-by-6-inch shaft, which should have come with the mower, into the hole on the right side of the back lift link.

After that, take off the belt on the mower. Then, take out the four clevis pins that hold the deck to the boat. Take out all four pins.

Now, push the mower elevator pedal toward the seat and remove the shaft from the hole on the rear right side of the lift link.

After that, the mower will move the lift pedal up, which will take a while. The last step is to move the deck under the mower to the right. That should take care of it!

But if you’ve never done it before, you should get help from an expert and do everything while they watch.

(6) Problem 6: The Engine won’t start

This is one of the Kubota z421 problems that come up most often. Many things can stop the engine from beginning. For example, switches need to be in the right place.

So, make sure the brake pedal is on correctly. Also, you should check to see if the PTO switch is off.

It can sometimes be caused by a problem with the fuel, like the ones inside the Kubota MX5400. So the next step is to check the fuel system. There might not be any gas, so you’ll have to fill up the tank.

This same fuel filter could also be clogged or old. So, please get a new one. Ensure the fuel has gone right because it wasn’t stored properly. This might lead to poor achievement and long-term damage to the engine.

(7) Problem 7: Center Blade Pulley Problem

The center pulley is the first problem many people have with their mowers.

Since the central belt broke, few people would have to change it twice a week.

Aside from this, people have also had a few other problems with the pulley on this Kubota Z421 zero-turn mower over time.

Those are…

  1. Fixed pulley.
  2. Very noisy pulley.


All of these problems are linked in some way. But check out what could be done to solve these problems.

Possible causes of the belt breaking or wearing out quickly are…

Check to see if the belt is very loose. When the belt is not tight enough, it can slip onto the pulley and wear out quickly.

Change how tight or lose the belt is, but make it all fast enough and loose. Keep it moderate and check to see if it’s moving out of place.

Small particles or grit can sometimes get stuck between the pulley and the belt. This could be another rationale for why the belt breaks or wears out more quickly.

Use a brush to clean the face of a pulley and the side of a belt.

Splicing the fastener is another thing that can cause the belt to wear out or slip out of place. Try making the pins tighter. You might even have to replace that in some situations.

Possible Reasons for Frozen Pulley

  • Two key variables delay or stop a pulley. First, “Defective bearing.”
  • Old, rusty bearings spell disaster. This freezes pulleys. The shaft is bent.
  • Check the shaft’s condition and placement. Bending the rod slows the pulley.
  • Replace a little bent shaft.

Possible Reasons for Pulley Being Very Noisy

  • If the belt is too loose, it will drop onto the pulley and generate noise.
  • Check the pulley mounting and support.

(8) Problem 8: The Engine is running rough

This is another of the most significant common problems with the Kubota z421. After the engine starts, you can see that it slows down. This problem could be caused by a spark that has broken.

By looking at it, you can tell if a plug is broken. There will be a thick layer of carbon buildup. It could also look rusty or burned. A good thing to do is to get a new spark plug. Putting in a new plug is simple.

A slow engine is also often caused by problems with the carburetor. The carburetor is in charge of keeping the right amount of air and fuel in the machine. But like any other portion of the mower, old gasoline can build up and make it dirty.

This buildup can stop the carburetor from mixing the right amount of air and fuel. In this particular instance, you will need to clean this same carburetor to have it working as it did before.

(9) Problem 9: Ignition Switch Problems

The ignition that comes with the Kubota Z421 is made of plastic. Also, the key to the mower is pretty short. I’ve just seen a user complain that the key doesn’t stay in the ignition keyhole after using the mower.

Since it is made of plastic, it will no longer hold the key if just a little bit of the polycarbonate wears out over time. It’s a flaw, and there’s not much you can do about it.

Use a rope to tie one end to a back of a key and the other to something that needs this same ignition switch. This is a do-it-yourself way to keep from losing the key when riding.

You wouldn’t lose the key that way.

(10) Problem 10: Weak Pipe Line

Few people have said anything wrong about the Kubota Z421 zero-turn mower’s fuel system pipe.

This same fuel system pipeline starts to leak at some point. Because of this, the engine takes in too much air, which makes the machine lose power.

This could be the reason your Kubota Z421 mower suddenly stopped working.


The only other thing to do is change the pipe. Try to put in a fuel line that is better made and will last longer.

Kubota z421 Reviews

Japanese firm Kubota makes agricultural equipment and other machinery. The domestic and commercial Kubota z421 zero-turn lawn mower. A 21-hp Kubota diesel engine powers its 61-inch cutting deck.

Customers like the Kubota z421. Its power, durability, and ease of use are popular. The mower is quieter than other versions, according to several reviews.

A Kubota z421 is a robust and durable home and commercial lawn mower. Its ease of use and many features make it a good pick for new mower buyers.

Belt Tension Spring Problems

It happens so often that it’s almost funny. The buckle tension spring keeps this same belt tight, which is essential for two reasons.

First, it keeps the girdle from slipping, which can cause much trouble. It also keeps the belt from breaking, which is the second reason.

The tension spring has been known to break easily, which is a shame. It’s normal to need more than one belt every 50–100 hours.

The Mower scalps the grass

Any mower can be judged by how well it cuts and doesn’t hurt the grass. Once your Kubota z421 begins to behead the grass, you could slowly destroy it.

You might be at fault for this problem. You could have set the cutting at a low height. This could also be because of the way the lawn is. It can be made of land that is uneven and bumpy.

In the first case, the right thing to do is to change the cutting height. But you have to change this identical anti-scalp roller if the lawn has bumps and uneven ground.

The mower deck will only touch the grass if these rollers are set up correctly. Check the air pressure in your tires while you are there. Close contact is less likely when the right amount of pressure is used.

Strange Dark exhaust

Your Kubota z421 shouldn’t be putting out a lot of colored smoke. If the exhaust is dark or gray, you should check the quality of the fuel. The second step is to check the filters and clean the clogged ones. Another thing to check is the choke on the mower.

In cold weather, the choke valve is supposed to help the engine warm up before it starts. So, it opens to let some atmosphere in and then closes automatically to ensure the air and gasoline mix well.

If this valve breaks for any purpose, it will get stuck and not close or open as it should. Then you will have to change where it is. Put some oil on it to make it work better.

Sometimes, this same linkage cable may be too tight to allow the valve close and open properly. Users can loosen its mount a bit to give it the proper movement.

Kubota z421 Price

The top-of-the-line Kubota Z421 zero-turning mower costs a little under $10,000. However, the Z421 is a commercial-grade zero-turn mower, so if you need one for your business, consider it a 23.5 HP diesel engine powers the 42′′ Kubota Z421 zero-turn mower.

Hydrostatic transmission lets it mow at 8.5 MPH. A mulching kit and 9.5-gallon fuel tank come standard. The Z421 commercial mower is sturdy.

It’s strong, durable, and includes everything you need to accomplish the job. A Kubota Z421 is indeed a top-tier zero-turn mower.

What Majority of the Users Feel About this Z421 Mower?

Well. This zero-turn mower is popular with Kubota Z421 owners. Why not? This mower can mow huge yards. This machine is also straightforward to use.

However, some people are upset about Kubota Z421’s difficulties. Clogged carburetors, fuel lines, etc.

However, the power to mow high-density grassy lawns, cutting quality, efficiency, ease of operation, and durability seem to exceed those minor concerns.

Kubota z421 Manual

Kubota’s Z400 series zero-turn mowers are for homeowners and professionals who want high performance, comfort, and reliability. Kubota’s flagship Z421 has many features that make it one of the best in its class. The Z421 has a 21-hp Kubota V-twin engine at 3600 rpm.

It cuts at 8.5 mph with a 61′′ cutting width. Kubota’s Smooth Deck Technology cuts better on the 7-gauge steel mower deck.

A button raises and lowers the deck, and the cutting height may be adjusted from 1.5′′ to 4.5′′. The Z421 has Kubota’s unique ACS (Automatic Blade Control System).

This mechanism protects the blades and engine by automatically engaging and disengaging them when the mower deck is lowered and lifted.

A luxurious high-back seat, cup holder, cruise control, and hour meter are standard on the Z421. Its 12.6-gallon gasoline tank lets you mow for hours without stopping. The Kubota Z421 is the best zero-turn mower.

Its many features make it one of the best in its class and ensure years of reliable service.

Kubota z421 Accessories

Kubota’s z421 zero-turn mower has many features to improve grass maintenance. The Kubota z421 accessories available to modify this mower make it stand out. Kubota z421 accessories include baggers, snow plows, and sunshades.

Because Kubota mowers were durable, your attachments will last season after season. Check out the Kubota z421 accessories to customize your mower. It will become your favorite lawn care equipment with the correct attachments.

Kubota z421 Problems: are they a deal breaker?

people are happy with their mowers. This mower has excellent features, like a powerful Kawasaki engine and fast performance. It can also cover large yards.

Still, some people who use this mower have different problems. Most of the time, these issues can be resolved by keeping up with routine maintenance.

Even if you prefer to avoid doing things yourself, you can always call a professional or go to your dealer for help with technical problems.

However, one of the best things about this mower is how cheap it is compared to other computers with similar features. The Kubota Z421 is flexible without going over your budget.

As for the cost of repairs, you won’t have to take this tractor to a shop every few months. If you take care of it, it can help you live longer.

Kubota z421 Kommander Pro

The Z421 Kommander Pro from Kubota is a zero-turn tractor with a lot of power and features to make mowing your lawn manageable.

This mower’s 21-hp Kubota diesel engine allows it to cut through thick weeds and grass. A Kommander Pro also includes a 60-inch cutting deck that makes even the most enormous lawns easy to take care of.

The Kommander Pro also emerges with a bagger connection, making it easy to gather grass clippings and leaves.

Kubota z421 Parts

Kubota z421 parts are among the most durable and trustworthy. To keep your mower functioning like new for years, we sell a comprehensive range of Kubota z421 components. We carry Kubota z421 engine, drivetrain, and mower deck parts.

MowerPartsUSA.com has Kubota z421 components. We have several Kubota z421 parts that keep your mower working for years. We carry Kubota z421 engine, drivetrain, and mower deck parts.

Kubota z421 parts are among the most durable and trustworthy. To keep your mower functioning like new for years, we sell a comprehensive range of Kubota z421 components. We carry Kubota z421 engine, drivetrain, and mower deck parts.

MowerPartsUSA.com has Kubota z421 components. We have several Kubota z421 parts that keep your mower working for years. We carry Kubota z421 engine, drivetrain, and mower deck parts.

Kubota Z421 Problems FAQs


(1) Are Kubota zero-turn mowers reliable?

Since 1988, Kubota has been making zero-turn mowers. Kubota’s zero-turn mowers are reliable, long-lasting, and good at work. Many people who have used Kubota zero-turn mowers for years haven’t had any significant problems.

The engines in Kubota zero-turn mowers are reliable and last a long time. The mowers also have parts that are made well. Because of this attention to detail, Kubota mowers that don’t turn can be used daily.

Kubota makes zero-turn mowers for people with different budgets and needs. Kubota makes small lawnmowers for homes and huge mowers for businesses. The warranties on Kubota zero-turn mowers are very long.

You don’t have to worry because you’re covered. Kubota makes dependable zero-turn mowers. You can choose a Kubota zero-turn mower that fits your needs from their wide range.

(2) Does Kubota use Kawasaki Engine?

Kubota does not employ Kawasaki engines. Instead, those who use machines that Kubota designed and built. A few sections in such engines may come from Kawasaki, but Kawasaki does not make the engines themselves.

(3) How many hours will a Kubota zero turn last?

Assuming you mean this same Kubota ZD series zero turn mowers, people are built to last and have a robust design.

The engines seem reliable and can run for at least 1500 hours if they are well taken care of. The transmissions also are tricky and, with the proper care, may last for many years.

The decks on such mowers are made of rigid materials and, with proper care, may last for several seasons.

(4) How much does a Kubota Z421 weight?

The Z421 zero-turn mower from Kubota weighs 819 pounds (369 kg). It has a 21-hp V-Twin Kubota engine and a 61-inch cutting width.

Final Words

👉 Kubota is calling back the Z421 zero-turn mowers because of a problem with the deck. This same problem is that deck can come off the mower while it’s being used, which is dangerous for the person using it and anyone nearby.

👉 Kubota is telling everyone who owns a Z421 to pause using it and call their local dealer to get a free repair.

This article I have created this to give you complete information about the Kubota Z421 Problems.

Check out the given details which help you to know about the Kubota Z421 Problems.

For more information visit our website: Commercialvehicleinfo.com

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