Yamaha YZ125(W)/W1 Owner's Service Manual page 524

Diameter of straight
portion
Clip position
Rich
1 richer
0.5 richer
STD
0.5 leaner
1 leaner
Lean
Rich
ø2.72 mm (0.1071 in) ø2.73 mm (0.1075 in) ø2.74 mm (0.1079 in) ø2.75 mm (0.1083 in) ø2.76 mm (0.1087 in)
6BFY44-72-3 6BFY44-73-3
6BFY42-72-4 6BFY42-73-4
6BFY43-72-3 6BFY43-73-3
6BFY42-72-3 6BFY42-73-3
6BFY43-72-2 6BFY43-73-2
6BFY44-72-1 6BFY44-73-1
6BFY42-72-2 6BFY42-73-2
SETTING
EC719072
Jet needle adjustment
(For USA and CDN)
On the carburetors used in the YZ125, the main
nozzle is a non disassembly type, so it can not
be replaced. Therefore,
requires the change of the jet needle.
1. The jet needle setting parts, having the
same taper angle, are available in different
straight portion diameters and in different
taper starting positions.
Standard jet needle
<Example>
6BFY42-74
Diameter of straight portion
Clip position
Taper angle
In the case of the same number of clip posi-
tion, changing
6BFY43-74 has the same effect as a rising
of 0.5-clip position. And in the case of the
same number of clip position, changing from
6BFY42-74 to 6BFY44-74 has the same
effect as a rising of 1-clip position.
A Difference in straight portion dia.
B Difference in clip position
a Reference needle
b 0.5 richer
c 1 richer
6BFY44-74-3
6BFY42-74-4
6BFY43-74-3
6BFY42-74-3
6BFY43-74-2
6BFY44-74-1
6BFY42-74-2
7-6
TUN
carburetor
6BFY42-74
from 6BFY42-74
Lean
6BFY44-75-3 6BFY44-76-3
6BFY42-75-4 6BFY42-76-4
6BFY43-75-3 6BFY43-76-3
6BFY42-75-3 6BFY42-76-3
6BFY43-75-2 6BFY43-76-2
6BFY44-75-1 6BFY44-76-1
6BFY42-75-2 6BFY42-76-2
setting
to