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NEEDLE JET
On the primary Choke type as in the CR-SPECIALS
offered by SUDCO the Needle Jet is part of the
Nozzle Holder. KEIHIN offers a Screen Type and
Flat Tyoe of Needle Jets. However, the Flat Type
comes standard in all CR-S from SUDCO. We have
found both street and racing applications that the
Flat Type is more eficient in the CR-S carburetors.
In any case, the Needle Jet is not a calibration parts
and jetting should be done by changing the Needle
(Jet Needle).
NEEDLE
The Needle has four factors:
1. Straight portion diameter (D)
2. Clip step
3. Straight portion length (L1)
4. Taper (A)
The inal low is metered at the opening between the
Needle and the Needle Jet.
MULTI-TAPER NEEDLE
Richer Mark
D
A&L
Y5 2.755
Y6 2.765
Y7 2.775 A1 = 0°50’
Y8 2.785
A2=3°30’
Y9 2.795
A3=1°30’
Y0 2.805
L1=50.3
Y1 2.815
L2=60.3
Y2 2.825
L3=65.3
Leaner
Y3 2.835
L4=83.3
Richer
YY5 2.755
YY6 2.765
YY7 2.775
A1= 0°50’
YY8 2.785
A2=3°30’
YY9 2.795
A3=1°30’
YY0 2.805
L1=50.3
YY1 2.815
L2=60.3
YY2 2.825
L3=65.3
Leaner
YY3 2.835
L4=83.3
Y and YY Needles are available in .01mm diameter
increments. YY is 2.7mm longer than Y.
Starter Valve
(Enricher Valve)
Richness at Starter Valve
“ON” is adjusted by the
Starter Jet.
CR Special Racing Carburetors
534
MARK
A
D
Clip Step
1
2
3
4
5
6
7
mark
Needle Jet