Honda 2007 CR125R, Owner'S Manual

Page: 107 / 144

Adjustments for Competition
103
Carburetor Adjustments & Tuning Tips
Carburetor Minor Adjustments
• The standard carburetor settings are ideal for
the following conditions: 32-to-1 premix ratio
using Pro Honda HP2 2-stroke oil or its
equivalent, sea level altitude, and 68 °F (20
°C) air temperature. If your conditions are
different, you may need to adjust the
carburetor settings, using the tuning
information on page 101 and 102. Confirm
your settings are correct before proceeding.
Minor Adjustments
1. Adjust the carburetor setting using the turning
information on page 101 and 102.
2. When the engine is warm enough to run
without the choke, push the choke knob down
to its off position.
3. Loosen the lock nut (1) and turn the throttle
stop screw (2) to obtain the smoothest idle:
– To decrease idle speed, turn the screw
counterclockwise.
– To increase idle speed, turn the screw
clockwise.
4. Tighten the lock nut while holding the throttle
stop screw to the specified torque:
1.5 lbf·ft (2 N·m, 0.2 kgf·m)
5. Adjust the air screw (3) to obtain the best
off-idle performance.
– If the engine blubbers (rich) exiting a
corner, turn the air screw counterclockwise
to lean the mixture.
– If the engine surges (lean) exiting a corner,
turn the air screw clockwise to richen the
mixture.
(1) lock nut (+) increase
(2) throttle stop screw (–) decrease
(3) air screw
The minimum to maximum range of air screw
adjustments is 1 to 3 turns out from the lightly
seated position. If you exceed 3 turns out, the
next smaller slow jet is needed. If you are under
1 turn out, the next larger slow jet is needed.
Adjustment Procedure
1. Warm up the engine.
2. Make 2 – 3 laps of a course with the standard
setting or corrected jetting (page 101) and
spark plug. Note engine acceleration and
other engine conditions in relation to throttle
opening. Verify carburetion by removing the
spark plug and reading its firing end (page 48,
109). It may take more than 2 – 3 laps to get a
good spark plug reading with a new spark
plug.
3. Change carburetor settings or select suitable
carburetor jets, taking into consideration the
engine conditions and factors for temperature
and altitude (page 101).
4. If you’ve determined that the main and slow
jets must be changed, you must remove the
float chamber plug.
Removing the float chamber plug will allow
the fuel in the float chamber to drain. Do not
remove the plug if the engine is hot.
5. Turn the fuel valve OFF, and disconnect the
fuel line from the fuel valve.
6. Loosen the connecting and insulator band
screws. Rotate the carburetor. Remove the
float chamber plug (4).
(4) float chamber plug
(2)
(1)
(+)
(–)
WARNING
Gasoline is highly flammable and
explosive. You can be burned or
seriously injured when handling fuel.
• Stop the engine and keep heat, sparks
and flame away.
• Handle fuel only outdoors.
• Wipe up spills immediately.
(4)
(3)
CR125R/101-110(31KSR620) 5/6/05 1:16 PM Page 103