Carburetor Adjustments & Tuning Tips
122
Adjustments for Competition
21. Tighten the insulator band screw (17) so the
gap between the tabs of the clamp is 0.3 ±
0.04 in (7 ± 1 mm).
22. Start the engine.
If the engine idle speed is too high or too low
or engine is not idling, adjust the engine idle
speed (page 48).
23. Repeat steps 4 – 22 until the engine gives
maximum power with the correct spark plug
reading. It is always better to jet a little rich
than a little lean. It is advisable to record the
settings, course conditions, lap times, and
climatic and barometric conditions for future
reference.
Refer to
Spark Plug
on page 52.
Check any jetting change by reading the spark
plug. The following procedure is recommended.
You may not get an accurate reading if you simply
turn off the engine and pull the plug for inspection.
Use a new spark plug. Inspect the plug before
installing it.
NOTICE
Using spark plugs with an improper heat range or
incorrect reach can cause engine damage.
Before removing the spark plug, clean the spark
plug area thoroughly to prevent dirt from entering
the cylinder.
Ride for 10 – 15 minutes before taking a plug
reading. A new plug will not color immediately.
To obtain an accurate reading of a new spark plug:
1. Accelerate at full-throttle on a straight.
2. Push the engine stop button and pull the clutch
lever in to release the clutch.
3. Coast to a stop.
4. Remove the spark plug.
5. Use a magnifying glass to inspect the spark
plug. The porcelain insulator (1) around the
center electrode (2) should appear clean and
colorless with a gray ring around the center
electrode where it exits the porcelain. Metallic
specks indicate lean jetting that is removing
metal from the piston. Black sooty streaks on
the porcelain indicate rich jetting.
NOTICE
An improperly tightened spark plug can damage
the engine. If a plug is too loose, the piston may be
damaged. If a plug is too tight, the threads may be
damaged.
Spark Plug Coloring Guidelines
Remember that in addition to improper jetting:
• A lean condition can be caused by air leaks in
the inlet tract or exhaust system, the passage of
too much air because of the use of the wrong
air cleaner, use of a less-restrictive aftermarket
exhaust system, or a hole or holes (deliberate
or unintentional) in the air cleaner housing.
• A rich condition can be caused by a plugged or
dirty air cleaner, use of a more-restrictive
aftermarket exhaust system, a clogged spark
arrester, or excessive oil on the air cleaner.
Excessive smoking will occur.
(17) insulator band screw
(17)
0.3 0.04 in
(7 1 mm)
±
±
Spark Plug Reading
(1) porcelain insulator
(3) side electrode
(2) center electrode
Condition
Spark Plug
Appearance
Mixture
Normal
Dark brown to light tan
color with dry
electrode
correct
Overheating
(Lean)
Light gray or white
color
lean
Wet
(Rich)
Wet or sooty
rich
(2)
(3)
(1)
31KSE7100_NA.book 122 ページ ２０１９年４月９日 火曜日 午後１時１３分
Summary of Contents for CRF150R 2020
Page 16: ...10 Before Riding 31KSE7100_NA book 10 ページ ２０１９年４月９日 火曜日 午後１時１３分 ...
Page 98: ...92 Servicing Your Honda 31KSE7100_NA book 92 ページ ２０１９年４月９日 火曜日 午後１時１３分 ...
Page 138: ...132 Tips 31KSE7100_NA book 132 ページ ２０１９年４月９日 火曜日 午後１時１３分 ...
Page 157: ...Consumer Information 151 31KSE7100_NA book 151 ページ ２０１９年４月９日 火曜日 午後１時１３分 ...
