Honda CR250R 2004 Owner's Manual page 53

5. CARBURETOR ADJUSTMENT
Carburetor Major Adjustments
NOTE:
•
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.
Standard settings:
Air screw opening — 1 1/2 turns out
Slow jet — #30
Jet needle — 6BHY38–73
Needle clip position — 2nd groove
Main jet — #420
Float level — 0.59 in (15.0 mm)
Identification number — TMX11C
50
All jetting is based on
•
Standard Jetting
•
32:1 Fuel/Oil Ratio
•
Unmodified Engine (Including Porting, Exhaust and Timing)
TEMPERATURE
FAHR. –21°~0°
ALTITUDE
AS: 1 1/2
10,000 ft SJ: 32.5
to
NC: 2nd
7,500 ft JN: 6CHY12-82
MJ: 420
AS: 1 1/4
7,499 ft SJ: 32.5
to
NC: 2nd
5,000 ft JN: 6CHY12-82
MJ: 430
AS: 1 1/2
4,999 ft
SJ: 35
to
NC: 2nd
2,500 ft
JN: 6CHY13-82
MJ: 440
AS: 1 1/4
2,499 ft SJ: 35
to NC: 3rd
1,000 ft JN: 6CHY12-82
MJ: 450
AS: 1
999 ft SJ: 35
to NC: 3rd
Sea Level JN: 6CHY12-81
MJ: 460
Legend
AS: Screw Opening from fully seated
SJ: Slow jet
NC: Needle Clip position
JN: Jet Needle
MJ: Main Jet
General changes due to temperature and altitude
Condition Mixture will be
Cold temperature Lean
Warm temperature Rich
Dry air Lean
High humidity Rich
High altitude
Rich
–1°~20° 19°~40° 39°~60° 59°~80°
1 3/4 2 2 1/4 2 1/2
30 30 30 30
1st
2nd 2nd 1st
6CHY12-82 6CHY12-83 6CHY13-82 6CHY13-83
390
420 410 400
1 1/2 1 1/2 1 3/4 2
32.5 30 30 30
1st
2nd 2nd 2nd
6CHY12-82 6CHY12-82 6CHY12-83 6CHY13-82
400
420 420 410
1 3/4
1 1/4 1 1/2 1 1/2
32.5 32.5 30 30
2nd
2nd 2nd 2nd
6CHY12-82 6CHY12-82 6CHY12-82 6CHY12-83
410
430 420 420
1 1/2
1 1/2 1 1/4 1 1/2
35 32.5 32.5 30
2nd
2nd 2nd 2nd
6CHY13-82 6CHY12-82 6CHY12-82 6CHY12-82
440 430 420 420
1 1/2
1 1/4 1 1/2 1 1/4
35 35 32.5 32.5
3rd 2nd 2nd 2nd
6CHY12-82 6CHY13-82 6CHY12-82 6CHY12-82
420
450 440 430
Adjust to Component affected
Richen Main jet (jet needle stage)
Lean Main jet (jet needle stage)
Richen Main jet (jet needle stage)
Lean Main jet (jet needle stage)
Lean Main jet (jet needle stage)
79°~100° 99°~120°
2 1/4 2 1/2
27.5 27.5
1st 1st
6CHY12-82 6CHY12-83
380 370
2 1/4 2
30 27.5
1st 1st
6CHY13-83 6CHY12-82
390 380
2 2 1/4
30 30
1st 1st
6CHY13-82 6CHY13-83
400 390
1 3/4 2
30 30
2nd 1st
6CHY12-83 6CHY13-82
410 400
1 3/4 2
30 30
2nd 2nd
6BHY38-73 6BHY38-74
420 410