Service And Adjustments; Carburetor Adjustments - Guardian GTV/GTH-990/760 OHVI series Owner's Manual

CLEANING SPARK ARRESTOR SCREEN
If the engine exhaust muffler has a spark arrestor screen,
inspect and clean the screen every 100 hours of operation
or once each year, whichever comes first.
NOTE: If you use your engine on any forest-covered, brush-
covered or grass-covered unimproved land, it must have a
spark arrestor. The spark arrestor must be
maintained in good condition by the owner/operator.
Clean and inspect the spark arrestor screen as follows:
Inspect the screen and replace if it is torn, perforated or
otherwise damaged. DO NOT USE a defective screen. If the
screen is not damaged, clean it with a commercial solvent.
If the spark arrestor is found to be damaged or defective, replace it.

SERVICE AND ADJUSTMENTS

ENGINE SPEED
CAUTION: The engine speed was properly adjusted at
the factory and should require no additional adjustment. Do
not attempt to change engine speed. If you believe the
engine is running too fast or too slow, take your engine to
an authorized service center for repair and adjustment.
CHANGING THE ENGINE GOVERNED SPEED
WILL VOID THE ENGINE WARRANTY.
The operating speed of this engine is maintained by either a
mechanical, flyweight type or an electronic stepper motor
controlled governor. DO NOT try to adjust the governed
speed setting for the following reasons:
• Operating the engine at high engine speeds is dangerous
and increases the risk of personal injury or damage to the
equipment.
• Operating the engine at low engine speeds with heavy
loads may shorten the engine's life.

CARBURETOR ADJUSTMENTS

The carburetor of your engine is pre-set at the factory. The
carburetor should not be tampered with because this will
VOID THE EMISSION CONTROL SYSTEM
WARRANTY. If you experience problems and your engine is
used at an altitude in excess of 5000 feet, contact the nearest
authorized dealer regarding high altitude setting changes.
10
GTV/GTH - 990/760 OHVI SERIES ENGINES
ADJUSTING VALVE CLEARANCE
After the first 100 hours of operation, you
should adjust the valve clearance in the engine.
IMPORTANT: If you feel uncomfortable about doing this
procedure or you don't have the proper tools, please take your
engine in to the nearest service center to have the valve
clearance adjusted. This is a very important step to insure
longest life for your engine.
Figure 10 - Valve Clearance Adjustment
To adjust valve clearance:
• Make sure the engine is at room temperature.
• Make sure that the spark plug wires are removed from the
spark plugs and out of the way.
• Remove the four screws attaching the valve cover with
a 10 mm wrench or socket.
• Make sure the piston is at Top Dead Center (TDC) of its
compression stroke (both valves closed). To get the
piston at TDC, remove the intake screen at the front of
the engine to gain access to the flywheel nut. Use a large
socket and socket wrench to rotate the nut and hence the
engine. While watching the piston through the spark plug
hole. The piston should move up and down. The piston is
at TDC when it is up as high as it can go.
• Loosen the rocker jam nut. Use an 10mm allen wrench
to turn the pivot ball stud while checking clearance
between the rocker arm and the valve stem with a
feeler gauge. Correct clearance is 0.002-0.004 inch
(0.05-0.1mm).
NOTE: You must hold the rocker arm jam nut in place as you
turn the pivot ball stud.