Honda CRF250R 2005 Owner's Manual page 126

Carburetor Adjustments & Tuning Tips
Standard Tuning Recommendations
For the following recommendations to be
accurate, you must use the standard settings as a
baseline. Also, don't change any of the settings
until you've determined what changes are
necessary.
Adjustment Standard settings
Pilot screw opening 1–3/4 turns out
Slow jet #42
Jet needle NCYQ
Needle clip position 3rd groove
Main jet #172
Float level 0.31 in (8.0 mm)
Identification number FCR01B
Adjustments for Altitude & Temperature
All jetting recommendations are based on
standard jetting with an unmodified engine. The
following conditions can affect the fuel mixture.
Condition Mixture will be Adjust to
Cold temperature Lean Richen
Warm temperature Rich Lean
Dry air Lean Richen
High humidity Rich Lean
High altitude Rich Lean
122
Adjustments for Competition
All jetting is based on
• Standard jetting
• Unmodified Engine
TEMPERATURE
ALTITUDE
10,000 ft
to
7,500 ft
7,499 ft
to
5,000 ft
4,999 ft
to
2,500 ft
2,499 ft
to
1,000 ft
Component affected
999 ft
Main jet
to
(jet needle stage)
Sea Level
FAHR. -21°~ 0° -1°~ 20°
PS: 1 3/4 1 3/4
SJ: 42 42
JN: NCYQ NCYQ
NC: 3rd 3rd
MJ: 172 170
PS: 1 3/4 1 3/4
SJ: 42 42
JN: NCYQ NCYQ
NC: 3rd 3rd
MJ: 175 172
PS: 2 1 3/4
SJ: 42 42
JN: NCYQ NCYQ
NC: 4th 3rd
MJ: 175 175
PS: 2 2
SJ: 42 42
JN: NCYQ NCYQ
NC: 4th 4th
MJ: 178 175
PS: 2 2
SJ: 42 42
JN: NCYQ NCYQ
NC: 4th 4th
MJ: 178 178
Legend
PS: Pilot Screw opening from fully seated
SJ: Slow Jet
JN: Jet Needle
NC: Needle Clip position
MJ: Main Jet
19°~ 40° 39°~ 60° 59°~ 80°
1 1/2 1 1/2 1 1/2
42 42 42
NCYQ NCYQ NCYQ
2nd 2nd 2nd
170 168 168
1 3/4 1 1/2 1 1/2
42 42
42
NCYQ NCYQ NCYQ
3rd 2nd 2nd
170 170 168
1 3/4 1 3/4 1 1/2
42 42 42
NCYQ NCYQ NCYQ
3rd 3rd 2nd
172 170 170
1 3/4 1 3/4 1 3/4
42 42 42
NCYQ NCYQ NCYQ
3rd 3rd 3rd
175 172 170
2 1 3/4 1 3/4
42 42 42
NCYQ NCYQ NCYQ
4th 3rd 3rd
175 175 172
79°~ 100° 99°~ 120°
1 1/4 1 1/4
42 42
NCYQ NCYQ
2nd 2nd
165 165
1 1/2 1 1/4
42 42
NCYQ NCYQ
2nd 2nd
168 165
1 1/2 1 1/2
42 42
NCYQ NCYQ
2nd 2nd
168 168
1 1/2 1 1/2
42 42
NCYQ NCYQ
2nd 2nd
170 168
1 3/4 1 1/2
42 42
NCYQ NCYQ
3rd 2nd
170 170