Adjusting The Speed Limiter; Checking The Spark Plug - Yamaha 2009 YFM25RY Service Manual

EAS29170

ADJUSTING THE SPEED LIMITER

The speed limiter keeps the carburetor throttle
from becoming fully-opened even when the
throttle lever is applied to the maximum posi-
tion. Screwing in the adjusting screw stops the
engine speed from increasing.
1. Measure:
• Speed limiter length "a"
Out of specification → Adjust.
Speed limiter length
Less than 12 mm (0.47 in)
2. Adjust:
• Speed limiter length
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a. Loosen the locknut "1".
b. Turn the adjusting screw "2" in or out until
the specified speed limiter length is
obtained.
Speed limiter length is
Direction "b"
decreased.
Speed limiter length is
Direction "c"
increased.
c. Tighten the locknut.
EWA14880
WARNING
• Particularly for a beginner rider, the speed
limiter should be screwed in completely.
Screw it out little by little as their riding
technique improves. Never remove the
speed limiter for a beginning rider.
• For proper throttle lever operation do not
turn out the adjusting screw more than 12
mm (0.47 in). Also, always adjust the
throttle cable free play to 2.0–4.0 mm
(0.08–0.16 in).
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EAS20690

CHECKING THE SPARK PLUG

1. Disconnect:
• Spark plug cap
2. Remove:
• Spark plug
ECA13330
Before removing the spark plug, blow away
any dirt accumulated in the spark plug well
with compressed air to prevent it from fall-
ing into the cylinder.
3. Check:
• Spark plug type
Incorrect → Change.
Manufacturer/model
NGK/DR7EA
4. Check:
• Electrode "1"
Damage/wear → Replace the spark plug.
• Insulator "2"
Abnormal color → Replace the spark
plug.
Normal color is medium-to-light tan.
5. Clean:
• Spark plug
(with a spark plug cleaner or wire brush)
6. Measure:
• Spark plug gap "a"
(with a wire thickness gauge)
Out of specification → Regap.
Spark plug gap
0.6–0.7 mm (0.024–0.028 in)
3-7
ENGINE