Needle Clip Position; Jet Needle; Needle Number; Main Jet - Suzuki RM250 Owner's Service Manual

4·3 MACHINE TUNING
Needle Clip Position
Lean
i
i
Rich
1
3
4
5
~
Needle
~
clip
The jet needle is linked to the th rottle valve by
means of the needle clip. Its lower part is ta-
pered and it has five grooves cut in the upper
part w here the needle clip fits .
To adjust the air/fuel mixture with the jet nee-
dle , c hange position of the needle clip w hich is
set in the 3rd groove. The lower groove the clip
is moved to , the higher the jet needle rises and
the la rger the clearance with the needle jet be -
comes, resulting in a richer air/fuel mixture ratio.
The needle clip position can be changed by half
to fine-tune the setting. To change the needle
clip position by half, change jet needle from NS
type to MS type. This change
w ill
move the
nee-
dle position by half to t he ri cher side. MS type
jet needles can be available as optional parts.
Air/fuel mixture Needle type and clip
position
l ean
R1470MS-lst
Rl4 70NS-2nd
R1470MS-2nd
R 14 70NS-3rd
R 1 470MS-3rd
R1470NS-4th
R 14 70MS-4th
R1470NS-5th
Ri ch
R1 470MS-5th
Jet Needle
0.0. of Needle
~
Clip
Taper angle
Needle number
R 1470 NS
r
\
L
Some alplabets are stamped
\ on the jet needle insted of "5".
0.0. 2.705 mm
Taper angle 1 0 45 '
~
Changing the needle itself controls air/fuel mix -
ture ratio particulary on lower mid-throttle open-
ing. The smaller the
D.O.,
the riche r the air/fuel
mixture becomes.
EX .
Needle Number Taper Angle
0.0 .
Rl469 NS 10 45'
2.695 mm
Rl470NS 1
0
45'
2.705 mm
Rl471 NS
1 0 45'
2.715mm
Main Jet
The main jet, like the slow jet, meters fuel flo w.
Each jet size is indicated by a number. Larger
number means a larger bore diameter and fitting
a larger numberd main jet enriches the air/ fuel
mixture.