Jet Needle Adjustment; Effects Of Changing The Jet Needle (Reference) - Yamaha YZ450F(W) Owner's Service Manual

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c
b
Diameter of straight portion
Clip position
Rich
1 richer
0.5 richer
STD
0.5 leaner
Lean
1 leaner
NFPR-4
NFLR-4
Rich
N
P
NFLN-5
NFLP-5
NFPN-4
NFPP-4
NFLN-4
NFLP-4
NFPN-3
NFPP-3
NFLN-3
NFLP-3
SETTING

Jet needle adjustment

The jet needle is adjusted by changing it.
Standard jet needle
The jet needle setting parts, having the same
taper angle, are available in different straight
portion diameters and in different taper starting
positions.
<Example>
NFLR - 4
Clip position
Diameter a of straight portion
b Reference needle
c 0.5 leaner
Changing from NFLR-4 to NFPR-4 has the
same effect as a rising of 0.5 clip position.
Q
R
NFLQ-5
NFLR-5
NFPQ-4
NFPR-4
NFLQ-4
NFLR-4
NFPQ-3
NFPR-3
NFLQ-3
NFLR-3
Effects of changing the jet needle
(reference)
(Diameter of the straight portion)
Changing the diameter of the straight portion
adjusts the air-fuel mixture when the throttle is
1/8 to 1/4 open.
È
1/4
È Idle
É Fully open
7 - 7
T U N
NFLR
S
T
NFLS-5
NFLT-5
NFPS-4
NFPT-4
NFLS-4
NFLT-4
NFPS-3
NFPT-3
NFLS-3
NFLT-3
1/2
3/4
Q
S
Lean
U
NFLU-5
NFPU-4
NFLU-4
NFPU-3
NFLU-3
É
+10%
R
–10%

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This manual is also suitable for:

Yz450f 2007Yz450f w 2007Yz450f 2006Yz450fw 2006

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