BBM MZ SERIES ZERO-TURN MOWER. Manual - part 5

SERVICE SECTION

SECTION 1: HYDROSTATIC SYSTEM

The hydrostatic system on MZ models is a sealed lifetime 
transaxle system, so no maintenance is required.  
Under the rear of the mower, you will find the two levers shown in 
the image. These bypass levers serve as a neutral for moving the 
mower while the engine is not running. Pull the levers out and 
lock them into place to activate the bypass. 

When adjusting the tracking on the mower, the length of the 
pushrods can be changed by screwing the swivel joint in or out 
on the ends of the rods. Shortening the overall length of the rod 
slows the pump down. Lengthening the rod will increase the 
speed of the pump.

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PAGE 19

SECTION 2: DRIVE BELT

 

Shown to the right is the MZ pump belt  
tensioner. Tightening the two 3/4"  jam nuts 
on the right  side will increase the belt tension. 

The tension should be adjusted so that there is 
between 60 to 65 lbs. of tension on the belt. 
This can be checked with a belt tension gauge 
as shown to the right.

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SECTION 3: ENGINE

540cc BRIGGS

This machine has an oil drain hose installed on the engine to 
allow for easier oil changes. Bad Boy  recommends that the oil 
and filter be changed after the initial 8 hrs of use, and at intervals 
of 50 usage hours or yearly, whichever occurs first after that. The 
oil capacity is 2 quarts. Bad Boy 10W-30 synthetic blend engine 
oil is recommended for maximum protection. 

The fuel filter is located in the fuel line about 12˝ from the 
carburetor on the side of the engine. Replace the filter yearly. 
Prior to the removal of the old filter, note the direction of fuel flow 
as indicated on the filter. Have towels readily available in order 
to quickly remove any fuel leakage. Always use new hose 
clamps and ensure the security of the new filter by lightly pulling 
on each hose. Always perform maintenance outdoors or in a well 
ventilated area. Do not smoke or allow any open flames in the 
vicinity of any maintenance activities.

The air cleaner is the engine’s only defense against damaging 
foreign particles. It is very important that the air cleaner element 
is inspected prior to each use. Remove 
the element and tap its sides in order to remove debris. Do not 
blow the filter out using compressed air. Doing so will greatly 
reduce the air cleaner’s effectiveness. Replace yearly; more 
often in dusty environments. Adhering to these practices will help 
prevent loss of power and premature engine failure.

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3.1 Changing the Spark Plug: 

1) In order to access the spark plug you:

will need to remove the rear engine cover. This
can be done by removing the four carriage bolts
in the rear with a ½”  wrench.

2) Remove the ignition wire from the spark

plug  and  using  a  5/8”  deep  socket  and
extension take the spark plug off of the engine.

3) Check the spark plug gap or insert your

new spark plug.

4) When re-installing spark plug do not

overtighten the spark plug.