Onan MJA Series Service Manual page 68

3.6 StartinqSystem
MODELS: ::M.JB AND MJC, (EXCEPT5::M.JB,PRIOR TO SPEC F)
NOTE: For::M.JA and earlier5MJB see generator, revolving armature.
These models use a separ::lte 12-volt starting motor, mounted on
the
rig.ht hand side of the engine, to drive the flywheel.
It
isa conventional
automotive starting motor with solenoid shift and an over-running cllltch.
The motor is controlled by the start solenoid in the control box. When
the control box solenoid is energized, the solenoid on the starter oper ­
ates, shifting the pinion to engage the flywheelring gear and feeding
current to the stnrting motor. Disconnecting the starter :elt end of
starting cycle varies according to model -'-on 705MJB and MJC the
centrifugal switch closes and on5MJB the start-disconnect relay is
'energized. The over-running clutch protects the starter armature from
d
overspeeds.
3.6.1 MAINTENANCE
Periodically check the starting circuit wiring for loose or dirty connec­
tions. Inspect the starter commutator and if it .is dirty, 'Clean with #00
sandpaper. Check the brushes for excessive wear and reduced seating
on the armature .
3.6.2 TESTING
Poor cranking performance can be caused bya faulty starting motor,
defective battery, insufficient capacity battery, or high resistance in
the starting circuit.
STARTING
MOTOR
'l,
r
:riYj
~(
-=,
t
I
SOLENOlD./
.TO START SOLENOID
IN CONTROL BOX
.&.7t.:2
GROUND CON ­
NECTION TO
ENGINE
BAT
TERY
FIG 3.6. A - PICTORIAL. STARTING MOTOR AND BATTERY
\.,