Bad Boy Mower Problems: Homeowner Troubleshooting Guide

Bad Boy Mowers are good quality, robust mowers that have an excellent reputation, although they can occasionally present problems. Fortunately, many a Bad Boy Mower repair can be carried out yourself as long as you know which parts need attention. Below we have outlined the key ways of fixing common Bad Boy problems including starting issues, deck problems and issues with the blades.

If you are experiencing Bad Boy Mower problems, start by identifying the area of the issue. Many problems originate from the deck and its components so it’s worth checking the mower belt’s slack and the components around it.

Quick Guide

ProblemPossible Causes
Deck Vibrating- Screws missing from the pulley system 
- Excessive wearing of the spindle key 
- Imbalanced blades
Deck Will Not Raise or Lower- Worn or rusted spindle 
- The screws holding the shaft are failing
- The actuator may not be properly sealed allowing moisture inside
- The screw shaft sleeve may be rusty
- Excessive wearing of the house sealing 
- The corners of the deck may not be level
Mower Won’t StartMany of the possible causes of these problems can be found by checking up on routined maintenance including: 

- An issue with the battery connection or low battery charge 
- Loose plug or spark plug wiring
- Water in the fuel tank 
- Old fuel in the fuel tank
- Dry fuel pump
- Fuel injection not working
- Loose connections or faulty wiring
- Incorrect starting procedures
- Clogged or damaged air filter
Belt Problems- The belt may be loose due to stretching or snapping
- A reduction in belt tension due to screws falling from the lock collar or pulley
Mower Dies When Blades Are Engaged- Issue with the operator present switch
- Damaged battery
- Grass length
- Damaged pulley
Blades Won’t Engage- Loose belt
- Faulty PTO switch 
- Damage to the clutch
Hydraulic Leak- Wear or damage around the transaxle
Spindle Problems- Spindles not heating up as they should 
- Excessive wearing of spindle bearing 
- Damage or bending of spindles
PTO Switch Problems- Switch is faulty

Bad Boy Mower Problems And How To Fix Them 

Deck Problems


If the deck is vibrating it may be caused by a missing screw, a worn spindle key, locked collars or imbalanced blades. 

Replacing or tightening of loose and missing screws can fix the deck vibrations. If the cause is a worn spindle key then it needs to be replaced. You can repair imbalanced mower blades by removing them, cleaning them and then grinding any areas that are bent or damaged to smooth them out. 

Deck Will Not Raise or Lower

If the deck is not raising and lowering as it should it could be due to a worn or rusted spindle, failing screws, a rusty screw shaft sleeve, worn sealing or an imbalanced deck. The issue could also be with the electrical components so if the other areas are fine, check the electrics. 

Firstly, check the condition of all of the screws. Secondly, remove and replace any screws that are loose or rusty. If the screw shaft sleeve is rusty give it a thorough clean. Once you have done this, check the seals and apply a sealant to any parts that are no longer properly sealed. Finally, if the deck is not level raise it and put it into the correct position. 

Mower Won’t Start

There are many possible reasons the mower won’t start. The problem could be related to an issue with the physical or electrical components. To make the issue easier to diagnose, work your way through this checklist: 

  • Firstly, check the charge and connection of the battery.
  • Secondly, make sure there is fuel and the fuel is fresh and free from water or contaminants.
  • Thirdly, check the condition of the spark plug and ensure it is in the right position. Replace the spark plug if it is worn or loose. 
  • Next, ensure the air filter is clean. If the filter is clogged it will cause issues with the engine. 
  • Check the wires and connections for breaks and damage.
  • Check all of the in-line fuses.
  • Finally, ensure you follow the starting procedures outlined in the operator’s manual.

Belt Problems

The main issue with the belt is that it has become loose as a result of stretching or snapping. The tension of the belt may be loose due to screws falling from the lock collar or pulley. If the belt is loose then it simply needs tightening. If the belt is worn or snapped then replace it with a new belt.

To remove the deck belt:

  • Firstly, turn the ignition off and remove the key.
  • Raise the deck.
  • Remove the pulley cover on the right hand side.
  • Take the belt retainer bolt.
  • Remove clutch bracket.
  • Finally, lift the belt, rotate the pulley until the belt comes loose.

Replace Belt 

  • Remove the ignition key and raise the deck to its highest position, then take off the pulley covers.
  • Route the belt through the deck pulleys and slip it onto the clutch.
  • Carefully put the belt onto the deck pulley on the left hand side. 
  • Fit the belt retainer bolt. 
  • Install the clutch bracket. 
  • Check the belt is properly routed and the belt tension is good.
  • Finally, reinstall the pulley covers.

Adjust Belt 

  • Use a wrench to adjust the jam nuts.
  • Use a belt tension gauge to check the belt is at the proper tension.

Mower Dies When Blades Are Engaged 

There are a couple of different reasons the mower dies when blades are engaged. Start by testing the seat switch and if this is all in working order, check the battery and pulley. The problem could be that something is getting in the way of the blades (including grass that is too high or thick). Below we have worked through each of the common issues:

Seat Switch Not Engaged

The seat switch is essentially the kill switch that turns off the engine if the operator is not in position. This is a safety feature but it can malfunction. 

Use the owner’s manual to help you locate the switch beneath the switch. Then make sure the pressure switch is in the right position and properly connected. 

Damaged Battery 

Firstly, check the battery connections to ensure there are now loose or damaged wires. Make sure the battery is charging properly and check it for signs of corrosion. In addition, the battery may need replacing if it is not holding charge or working as it should. 

Grass Length 

If the grass is too high or too thick it can cause the mower to shut off. This happens because the cutting engine is working so hard that the mower stalls. 

Damaged Pulley

Damage or missing screws can impact the effectiveness of the pulley. Therefore, you need to check the condition of the pulley and fix or replace it if damage is found. 

Blades Will Not Engage

The blades not engaging could be due to an electrical problem. It is worth checking the PTO switch first and then checking the wires and connections. Use this checklist to help identify the problem:  

  • Firstly, plug in the safety switch. (The location of this is on the bottom of the seat.)
  • Secondly, check the PTO switch to ensure it is secure.
  • Thirdly, check for loose wires and connections.

This advice is in alignment with the Bad Boy Mowers troubleshooting advice on blades not engaging. 

Hydraulic Leak 

A hydraulic leak could be caused by a worn or damaged seal or a break in the hydraulic line. Check the line and seals for leaks but be aware the fluid can easily run so the source may be higher than where you see the drips. 

Hydraulic leaks are often the cause of transaxle issues, although these issues could also be caused by a damaged or defective hydro system/charge pump. If you are experiencing issues with a hydraulic leak, the best thing to do is install a new seal kit. However, if the hydro system is defective, get a mechanic to diagnose and fix the issue. 

Spindle Problems

The spindles are responsible for ensuring the blades spin properly. Therefore they are located on the cutting deck. If the spindle has damage to it, it can cause the blades to spin unevenly resulting in an uneven cut. 

However, if you look closely at the spindles you will be able to see if they are bent and need replacing. Other signs that the spindles need replacement or repairing include buzzing noises, squealing sounds and slow heat up times as explained below. 

Slow Heating 

The spindle preload may be the issue if it takes the spindle 30 minutes+ to heat up. 

Bent Spindle

Firstly, visually check the spindles to see if there is any damage or bending. If you can see damage or the spindles are worn, remove and replace them with new ones. 

Low Vibrations 

If you are experiencing buzzing sounds when using the mower, the issue may be the bearings. Excessive wearing of the bearings is common. Therefore, it is necessary to check the condition of the bearings and replace them.


Worn bearings or damaged spindles can also cause a high pitched squealing sound. Remove the spindles and bearings and replace the worn parts with new ones before reinstalling. 

PTO Switch Problems

Some of the problems we have looked at, such as the blades not engaging, may be causing the PTO issues. Firstly, check the PTO by testing via a multimeter. This will let you know if the PTO is working. If it is then you can begin troubleshooting the electrical and mechanical components that work with the PTO. If the multimeter does not give any values when testing the PTO then it means the PTO needs a replacement. 

B-In Now Code

The B-In Now code 6 1 n now appears after 5 hours and lets you know that it is time for an oil change. This code helps you keep the engine in good condition as a brand new engine may have metal shaving from new parts as well as dust and shavings. That is why it is necessary to change the oil after the first 5 hours of use. 

Bad Boy Lawn Mower Recalls 

As a result of a fire hazard issue with Kawasaki engines there are a number of Bad Boy Mowers that have been involved in recalls. The recall engines have a print of “Kawasaki” on the top along with the model number. The specification and serial numbers are also on a label on one side of the engine. This includes:

  • Bad Boy Mower FR651V (AS19) and (BS17)
  • FR730V (AS16) and (AS14)
  • Mower FX850V (AS15) and (ES09)

Check this list for up to date information on lawn mower recalls. 

Related Questions 

How much oil does a Bad Boy Mower take?

A Bad Boy Mower takes between 2 – 4.5L of oil depending on the model. Gas engines require 10W30 motor oil while diesel engines need 15W40 oil. Bad Boy hydraulic systems use 20W50 motor oil. 

Are zero turn mowers better on hills?

No, hills are one of the main weaknesses of zero turn mowers. They lack the stability and traction needed to handle steep hills. However, the majority of zero turn mowers can handle slopes of 10-15 degrees.  

Are zero turn mowers expensive?

The price of zero turn mowers depend on their grade, size, and features, but you can expect the pay between $1,500 – $4,000 for a mid-range mower. 

Summing It Up

To sum up, there are lots to consider when solving Bad Boy mower issues. Start by narrowing down the key problem and working from there to find the cause. Fortunately, it is possible to identify most of the issues during a thorough visual check of the mower.