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Jet Needle
The jet needle controls fuel/air mixture over 1/16
to 3/4 throttle. The straight section (1) affects
throttle response at smaller throttle openings. By
changing the position of the clip (2) in its groove,
you can improve acceleration at medium low and
medium speed.
1st
2nd
LEANER
3rd
4th
5th
RICHER
(1) straight section
(2) clip
Slow Jet and Air Screw
Refer to Carburetor Minor Adjustments (Page
91).
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
Air screw opening
2 turns out
Slow jet
#45
Jet needle
NFSF
Needle clip position
3rd groove from top
Main jet
#142
Float level
0.75 in (19.0 mm)
Identification number
PWK10A
All jetting is based on
• Standard Jetting
• 32:1 Fuel/Oil Ratio
• Unmodified Engine (Including Porting, Exhaust and Timing)
TEMPERATURE
ALTITUDE
3050m
(2)
(10,000 ft)
to
2300m
(1)
(7,500 ft)
2299m
(7,499 ft)
to
1500m
(5,000 ft)
1499m
(4,999 ft)
to
750m
(2,500 ft)
749m
(2,499 ft)
to
300m
(1,000 ft)
299m
(999 ft)
to
0m
Sea Level
Legend
AS: Air Screw opening from fully seated
SJ: Slow Jet
NC: Needle Clip position
JN: Jet Needle
MJ: Main Jet
Carburetor Adjustments & Tuning Tips
Cent
–30 ~ –17°
–18 ~ –6°
–7 ~ 5°
FAHR.
–21 ~ 0°
–1 ~ 20°
19 ~ 40°
AS:
2
2
SJ:
45
45
NC:
3
3
JN:
NBKF
NFSF
MJ:
142
142
AS:
1 3/4
2
SJ:
45
45
NC:
3
3
JN:
NBKF
NBKF
MJ:
145
142
AS:
2
1 3/4
SJ:
48
45
NC:
3
3
JN:
NBKE
NBKF
MJ:
148
145
AS:
1 3/4
2
SJ:
48
48
NC:
4
3
JN:
NFSE
NBKE
MJ:
150
148
AS:
1 1/2
1 3/4
SJ:
48
48
NC:
4
4
JN:
NBKE
NFSE
MJ:
152
150
4 ~16°
15 ~ 27°
26 ~ 38°
39 ~ 60°
59 ~ 80°
79 ~ 100°
2 1/4
2 1/2
2 3/4
45
45
45
2
2
2
NBKF
NBKG
NSFG
NSFG
140
138
135
2
2 1/4
2 1/2
45
45
45
3
2
2
NFSF
NBKF
NBKG
NSFG
142
140
138
2
2
2 1/4
45
45
45
3
3
2
NBKF
NFSF
NBKF
NBKG
142
142
140
1 3/4
2
2
45
45
45
3
3
3
NBKF
NBKF
NFSF
NBKF
145
142
142
2
1 3/4
2
48
45
45
3
3
3
NBKE
NBKF
NBKF
148
145
142
Adjustments for Competition
37 ~ 49°
99 ~ 120°
3
3
45
42
2
1
NBKG
132
130
2 3/4
3
45
45
2
2
NSFG
135
132
2 1/2
2 3/4
45
45
2
2
NSFG
138
135
2 1/4
2 1/2
45
45
2
2
NBKG
140
138
2
2 1/4
45
45
3
2
NFSF
NBKF
142
140
89
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