Yamaha YZ450F(S), Owner'S Service Manual

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T U N
Jet needle adjustment
(For USA)
The jet needle is adjusted by changing it.
The jet needle setting parts, having the same
taper angle, are available in different straight
portion diameters and in different taper starting
positions.
b
Reference needle
c
0.5 richer
d
0.5 leaner
Changing from NCVQ-4 to NDJQ-4 has the
same effect as a lowering of 0.5 clip position.
Standard jet needle NCVQ
<Example>
NCVQ - 4
Clip position
Diameter
a
of straight portion
b
d
c
NCYQ-4
NCVQ-4
NDJQ-4
Diameter of straight portion
Clip position
Rich Lean
M N P Q R S T
Rich
Lean
1 richer NCVM-5 NCVN-5 NCVP-5 NCVQ-5 NCVR-5 NCVS-5 NCVT-5
0.5 richer – – NCYN-4 NCYP-4 NCYQ-4 NCYR-4 NCYS-4 – –
STD NCVM-4 NCVN-4 NCVP-4 NCVQ-4 NCVR-4 NCVS-4 NCVT-4
0.5 leaner – – NDJN-4 NDJP-4 NDJQ-4 NDJR-4 NDJS-4 – –
1 leaner NCVM-3 NCVN-3 NCVP-3 NCVQ-3 NCVR-3 NCVS-3 NCVT-3
SETTING