Spark Plug; Cooling Fins - Honda GX25 Owner's Manual

SPARK PLUG

Recommended Spark Plug:
The recommended spark plug has the correct heat range for
normal engine operating temperatures.
An incorrect spark plug can cause engine damage.
For good performance, the spark plug must be properly gapped
and free of deposits.
1. Remove the top cover.
Loosen the 5 mm hex bolt with a hexagon wrench, then remove
the top cover.
Do not operate the engine when the top cover is
removed.
Do not pull the recoil starter handle when the top
cover is removed.
You may be injured from the rotating parts or burned
by the muffler.
TOP COVER
2. Disconnect the spark plug cap, and remove any dirt from around
the spark plug area.
3. Remove the spark plug with a 5/8-inch spark plug wrench.
SPARK PLUG
SPARK PLUG CAP
CM5H (NGK) CMR5H (NGK) ,
5 mm HEX BOLT
4. Inspect the spark plug.
Replace it if damaged or
badly fouled, if the sealing
washer is in poor condition,
or if the electrode is worn.
5. Measure the spark plug
electrode gap with a wire-
type feeler gauge. Correct the
gap, if necessary, by carefully
bending the side electrode.
The gap should be:
0.6 0.7 mm (0.024 0.028 in) − −
6.
Install the spark plug carefully,
by hand, to avoid cross-
threading.
7. After the spark plug is seated, tighten with a 5/8-inch spark plug
wrench to compress the sealing washer.
When installing a new spark plug, tighten 1/2 turn after the spark
plug seats to compress the washer.
When reinstalling the original spark plug, tighten 1/8 1/4 turn
after the spark plug seats to compress the washer.
A loose spark plug can overheat and damage the engine.
Overtightening the spark plug can damage the threads in the
cylinder head.
8. Attach the spark plug cap to the spark plug.
9. Install the top cover, and tighten the 5 mm hex bolt securely
with a hexagon wrench.

COOLING FINS

Inspection
1. Loosen the 5 mm hex bolt, then remove the top cover.
2. Disconnect the spark plug cap.
3. Inspect the engine cooling fins, and clean out debris if necessary.
SPARK PLUG CAP
COOLING FINS
4. Reconnect the spark plug cap.
5. Install the top cover, and tighten the 5 mm hex bolt securely.
ENGLISH
SIDE ELECTRODE
0.6 0.7 mm −
(0.024 0.028 in) −
SEALING
WASHER
−
11