Checking The Spark Plug; Measuring The Compression Pressure - Yamaha R15 2022 Service Manual

EAS30620

CHECKING THE SPARK PLUG

1. Remove:
• Lower side cowling (right)
Refer to "GENERAL CHASSIS (3)" on page
4-3.
2. Disconnect:
• Spark plug cap
3. 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 falling
into the cylinder.
4. Check:
• Spark plug type
Incorrect → Change.
Manufacturer/model
NGK/MR8E9
5. Check:
• Electrode "1"
Damage/wear → Replace the spark plug.
• Insulator "2"
Abnormal color → Replace the spark plug.
Normal color is medium-to-light tan.
6. Clean:
• Spark plug
(with a spark plug cleaner or wire brush)
7. Measure:
• Spark plug gap "a"
(with a wire thickness gauge)
Out of specification → Regap.
Spark plug gap
0.8–0.9 mm (0.031–0.035 in)
8. Install:
• Spark plug
2
1
3-8
ENGINE
Spark plug
13 N·m (1.3 kgf·m, 9.6 lb·ft)
TIP
Before installing the spark plug, clean the spark
plug and gasket surface.
9. Connect:
• Spark plug cap
10.Install:
• Lower side cowling (right) & other removed
parts
Refer to "GENERAL CHASSIS (3)" on page
4-3.
EAS30037
MEASURING THE COMPRESSION
PRESSURE
TIP
Insufficient compression pressure will result in a
loss of performance.
1. Measure:
• Valve clearance
Out of specification → Adjust.
Refer to "ADJUSTING THE VALVE CLEAR-
ANCE" on page 3-4.
2. Start the engine, warm it up for several min-
utes, and then turn it off.
3. Remove:
• Rider seat
• Lower side cowling (right)
Refer to "GENERAL CHASSIS (3)" on page
4-3.
4. Disconnect:
• Spark plug cap "1"
5. Remove:
• Spark plug
CHK
ADJ