5 Common Problems With Kubota Z121S

Kubota Z121S Problems

The Kubota Z121S mower is part of the Z100 series of Kubota lawn mowers. Since 2014 this Kubota tractor has been manufactured to great specifications of comfort and high performance. Its infinite forward and reverse gears coupled with hydrostatic transmission make it not only a unique zero turn mower but also a make of exceptional power and reliability. This Kubota Z121S lawn mower is equipped with an exceptionally differential power steering. However, like other lawn mowers it has its own challenges too. These are discussed below.

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1. Cranks But Does Not Start

One of the problems with the Kubota Z121S tractor which is a zero turn mower is that it can sometimes crank but not start. You will have to be on the driver’s seat if you tried starting it and it did not start. Also make sure that you have applied the parking brake and that the motion control levers are in neutral lock position. Don’t forget to make sure that the key is turned on in ‘on’ position. Also check to see if there is fuel in the fuel tank of the Kubota Z121S zero turn mower and that generally fuel is getting into the tank without any difficulties.

Sometimes the Kubota Z121S zero turn mower won’t start if you have filled it with poor fuel. To correct this replace the fuel with that one of a much better quality. Also check if the fuel system is not damaged or clogged. Attend to any anomalies in this regard. Check and change the filters as well in case this might be the problem. You will then do well to check the spark plug in case it might need some adjustment. Also, adjust the spark plug gap should this help. In the event that the spark plug is malfunctional, replace it.

2. Overheating of the engine

The Kubota Z121S zero turn lawn mower is also prone to engine overheating problems at times. This normally results from overworking the machine. So the immediate solution will be to lower the speed as well as reducing the load that the lawn mower is meant to tackle. Overheating could also be a sign that the engine oil is insufficient and might need to be replenished. This problem of the Kubota Z121S zero turn mower may be indicating that the engine air intake screen and cooling fins are dirty. In case this is the problem then clean them.

It might also be very helpful to check and see if the fan belt is there and is tight enough. If it’s looseyou will then need to tighten it. Thoroughly inspect this fan belt as it’sinefficient might result from its damaged nature because of cracks or some other broken part. If this proves to be the problem then replace it with a new one. Also check the radiator of this Kubota Z121S in case the core and the screens might be dirt. Clean them to rectify this problem.

3. Steering Problems

The steering problems that the Kubota lawn mower experiences can range from the steering wheel becoming flimsy to experiencing it pulling to one side. This might be a result of insufficient liquid in the steering wheel of the Kubota Z121S mower so checking if it is there and replacing it if its low would solve this problem. Identify any leaks as you check for the level of the hydraulic oil in case there could be any.

Quite surprising but then this can happen, if the Kubota Z121S lawn mower has difficulties in operating the steering wheel, the problem might be pointing to the tyres. Make sure that they are not flat. They should not have very low pressure in them either. If this proves to be the problem then add more pressure to the recommended standard. It might also become necessary to change them should this help.

Remember that for the steering wheel to swing in the desired directions with dexterity there should be sufficient oiling within the linkage. In this way the steering linkage should be checked to see if any addition of oil is needed.Don’t allow your steering wheel to have too much free play. If this proves to be your condition then you will need professional dealership in addressing this problem.

4. Excessive vibration

Another problem that the Kubota Z121S zero turn lawn mower might experience is that of excessive vibration. This is can be a result of accumulation of debris or some junk material on mower deck or in the pulleys. So, to rectify this problem you will need to clean the mower deck as well as the pulleys and remove any interference caused by dirt. Excessive vibration may also be a result of the damaged lawn mower belt which will need a replacement. As well, the lawn mower can experience this problem if the blades are unbalanced. If this happens then make sure that the blades are balanced by way of sharpening them evenly.

5. Coloured Exhaust fumes

The coloured exhaust fumes that come out of the Kubota Z121S lawn mower might be white or blue. They indicate that the lawn mower could possibly have excessive oil in the engine. To correct this, you will need to reduce the oil to the recommended level. The fumes might also be a result of a worn out piston ring.

At other times the piston ring might be stuck where it’s not supposed to be. Whatever the case in this regard, the piston ring will need to be checked and replaced with a new one. However, for this to take place there is a need for you to see your local Kubota Z121S dealer as this will involve the opening of the engine and is usually a delicate process.


The presence of the dual operation levers of the Kubota Z121S giveit both smooth and precise control for delicate trimming of lawns. This is handy for work around flowerbeds as well as trees and any other places where it can operate.Possession of a Kubota lawn mower is advantageous in that it has low-maintenance. When operating it, it has proven to be comfortable toobecause of the legroom up frontemanating from the wide foot pan. Working while seating on this lawn mower makes mowing easy and doable.Despite its problems, this lawn mower is still a preferred brand by many users.