Valve/Tappet Gap
Adjustment
After approximately one hour of
operation, tappet gap adjustment may be
necessary. When you check the valves,
lubricate the moveable parts. Also make
sure the screw is in tight before making
adjustments to valves.
Adjust the valves to a clearance of
.03mm to .10mm (.002 to .004 in) using
the supplied gauge. The valves must
be adjusted with the engine cold due to
thermal expansion.
Note:
Valves must be in the compression
stroke or closed position as shown in
the following figure. When adjustment
is completed, make sure you tighten the
lock nut.
How to Adjust
Remove the plug and the rocker arm
cover and revolve the propeller slowly
clockwise by hand. The intake side
rocker arm stops, and by turning it, the
piston reaches the compression top dead
center (TDC).
In that position, adjust with the included
gauge and hexagonal wrench so tappet
gap may be set to almost zero when the
engine is in the compression stroke. If
the gauge can enter (a limit gauge with
a 0.1 mm thickness), the clearance is at
maximum and needs adjustment, adjust
between 0.03 and 0.10mm (0.002 to
0.004 in.) After the gap is checked,
tighten the locknut securely. Do not
over-tighten.
The tappet gap is the most important
factor in the maintenance of 4-stroke
engines, and operation with an excess
clearance will degrade performance.
In particular, a large gap aggravates
abrasion of the tappet and the cam and
also increases the unusual sound.
Carburetor
Maintenance
Should you experience difficulty with
the carburetor of your engine:
• Factory settings for the idle needle
valve are about 4 turns out from a fully
closed position.
• The high-speed needle valve is set to
about 2 1/3 turns out from a fully
closed position and is a good point to
start from.
Generally speaking, there are very few
things that will keep today’s modern
gasoline engines from starting. To that
end, make sure you are using good-
quality “fresh” fuel, the spark plug is
good, and the ignition system is working
properly.
Check the battery voltage to make
sure the ignition is getting the proper
voltage. Should the engine fail to start
after these items are verified, refer to the
Troubleshooting Guide on page 11.
Tappet Adjustment
Adjust between
0.03 – 0.10mm (.002 in – .004 in)
Gauge
(0.1mm Max.)
Screw
N O T E S
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V A L V E / T A P P E T G A P A D J U S T M E N T
14387 SAI FG_20andFG_36 Manual.indd 12-13
12/16/08 2:09:13 PM
