Since the coupling bearing is made to extremely close tolerances, the clearance can not normally be measured.

NOTE
It is not necessary to remove the coupling bearing for inspection. If the bearing is removed, it will need to be replaced with a new one.
If the bearing play, roughness or binding is found, replace the bearing.
Coupling Bearing Lubrication
Pack the bearing with high-temperature grease. Turn the bearing around by hand a few times to make sure the grease is distributed uniformly inside the bearing.
Coupling Bearing Installation
Coupling Damper InspectionArmature Inspection
Using the × 1 Ω hand tester range, measure the resistance
between any two commutator segments [A].
Special Tool - Hand Tester: 57001-1394
If there is a high resistance or no reading (∞) between any
two segments, a winding is open and the starter motor
must be replaced.
...
Additional Considerations for High Speed Operation
Brakes: The importance of the brakes, especially during high speed
operation,
cannot be overemphasized. Check to see that they are correctly adjusted and
functioning
properly.
Steering: Looseness in the steering can cause loss of control. Check to see that
the handlebar turns freely but ha ...
Tire Tread Wear Inspection
As the tire tread wears down, the tire becomes more susceptible
to puncture and failure. An accepted estimate is
that 90% of all tire failures occur during the last 10% of tread
life (90% worn). So it is false economy and unsafe to use
the tires until they are bald.
Measure the tread depth a ...