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Old Skool_R’s Factory-Carb Specifications
GSX-R 750
1986 U.S.
Type: BST31SS
Main Jet: 117.5
Main Air Jet: 1.7mm
Jet Needle: 4C71
Needle Jet: P-8
Pilot Jet: 32.5
Pilot Air Jet: 160
Pilot Screw Setting: Preset
Starter Jet (choke): 40
Float Height: 14.6mm (+/- 1mm)
1987 U.S.
Type: BST34SS
Main Jet: 112.5
Main Air Jet: 1.8mm
Jet Needle: 4C09-1
Needle Jet: O-6
Pilot Jet: 35
Pilot Air Jet: 145
Pilot Screw Setting: Preset
Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
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1985 through 1987 U.K.
Type: VM29SS
Main Jet: 97.5
Main Air Jet: 0.5mm
Jet Needle: 6DP-2-3
Needle Jet: P-5
Pilot Jet: 32.5
Pilot Air Jet: 1.6mm
Pilot Screw Setting: Preset (1 1/2 turns out)
Starter Jet (choke): 42.5
Float Height: 14.2mm (+/- 1mm)
1988 and 1989
Type: BST36SS
Main Jet: 112.5
Main Air Jet: 0.5mm
Jet Needle:
U.S: 5FZ91
U.K: 5FZ89-3
Needle Jet: Y-5
Pilot Jet
U.S: 32.5
U.K: 37.5
Pilot Air Jet
California: 1.45mm
U.S except California: 1.55mm
U.K: 1.40mm
Pilot Screw setting
U.S: Preset
U.K: Preset (1 1/2 turns out)
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Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
1990-1992
Type
California: BST36SS
Except California: BST38SS
Main Jet
California: 112.5
U.S except California: 127.5
U.K: 117.5
Main Air Jet
California: 0.5mm
U.S except California: Cylinders 1 and 4= 0.9mm / Cylinders 2 and 3= 1.2mm
U.K: 0mm (blank)
Jet Needle
California: 5FZ91
U.S except California: 5ZDZ3
U.K: 6ZD7-3
Needle Jet
California: Y-5
Except California: O-8
Pilot Jet
U.S: 37.5
U.K: 32.5
Pilot Air Jet
1990: 1.2mm
1991 on: not specified
Pilot Screw Setting
U.S: Preset
U.K: Preset (1 1/8 turns out)
Starter Jet (choke)
California: 45
Except California: 40
Float Height
California: 14.6mm (+/- 1mm)
Except California: 14.7mm (+/- 1mm)
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GSX-R1100
1986-1988
Type: BST34SS
Main Jet: 130
Main Air Jet: 0.6mm
Jet Needle
U.S: 5D29
U.K: 4D13-3
Needle Jet
U.S: P-2
U.K: O-9
Pilot Jet
U.S: 32.5
U.K: 42.5
Pilot Air Jet
U.S: 135
U.K: 150
Pilot Screw setting
U.S: Preset
U.K: Preset (2 turns out)
Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
1989-1992 U.S.
Type: BST36SS
Main Jet: 122.5
Main Air Jet: 1.5mm
Jet Needle
California: 5D43
U.S except California: 5D42
Needle Jet: O-8
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Pilot Jet: 30
Pilot Air Jet
1989 and 1990
California: 1.35mm
U.S except California: 1.2mm
1991 and 1992: Not specified
Pilot Screw setting: Preset
Starter Jet (choke)
1989 and 1990: 45
1991 and 1992: 42.5
Float Height: 14.6mm (+/- 1mm)
1989 and 1990 U.K.
Type: BST36SS
Main Jet: 122.5
Main Air Jet: 1.5mm
Jet Needle: 5E60-3
Needle Jet: O-8
Pilot Jet: 40
Pilot Air Jet: 1.4mm
Pilot Screw setting: Preset (2 turns out)
Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
1991-1992 U.K.
Type: BST40SS
Main Jet: 125
Main Air Jet: 1.2mm
Jet Needle: 6ZD13-3
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Needle Jet: P-2
Pilot Jet: 40
Pilot Air Jet: Not Specified
Pilot Screw setting: Preset (2 turns out)
Starter Jet (choke): 40
Float Height: 14.7mm (+/- 1mm)
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Katana Factory Carb Specifications
Katana (GSX600F)
1988-89 (US Models)
Type BST31SS
Main Jet
Cylinders #1 and #4: 137.5
Cylinders #2 and #3: 135
Main Air Jet: 1.0mm
Jet Needle
California: 4CZ-5-1
Except California: 4CZ-4-1
Needle Jet: P-8
Pilot Jet
California: 37.5
Except California: 32.5
Pilot Air Jet
California: 155
Except California: 150
Pilot Screw setting: Preset
Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
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1988-89 (UK Models)
Type: BST31SS
Main Jet
Cylinders #1 and #4: 137.5
Cylinders #2 and #3: 135
Main Air Jet: 1.0mm
Jet Needle: 4CZ-3-3
Needle Jet: P-9
Pilot Jet: 40
Pilot Air Jet: 160
Pilot Screw setting
1988: 1-7/8 turns out
1989: Preset
Starter Jet (choke): 45
Float Height: 14.6mm (+/- 1mm)
1990 U.S.
Type: BST33SS
Main Jet: 112.5
Main Air Jet: 0.5mm
Jet Needle
California: 5F105
Except California: 5F104
Needle Jet: P-2
Pilot Jet: 32.5
Pilot Air Jet
California: 1.45mm
Except California: 1.55mm
Pilot Screw setting: Preset
Starter Jet (choke): 35
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1990 U.K.
Type: BST33SS
Main Jet: 110
Main Air Jet: 0.5mm
Jet Needle: 5FZ 102-3
Needle Jet: P-3
Pilot Jet: 32.5
Pilot Air Jet: 1.3mm
Pilot Screw setting: 1 1/2 turns out
Starter Jet (choke): 35
Float Height: 14.6mm (+/- 1mm)
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Katana 750 (GSX750F)
1988-1996
Type: BST36SS
Main Jet
U.S , cylinder #3: 110
All others: 105
Main Air Jet: 0.5mm
Jet Needle
California: 5EZ53
U.S except California: 5EZ62
U.K: 5EZ61-3
Needle Jet
U.S: Y-1
U.K: Y-2
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Pilot Jet
U.S: 32.5
U.K: 37.5
Pilot Air Jet
1989 and 1990 California: 1.25mm
1991 on California: 1.2mm
U.S except California: 1.35mm
U.K: 1.3mm
Pilot Screw setting
U.S: Preset
U.K: Preset (1 5/8 turns out)
Starter Jet (choke): 37.5
Float Height: 14.6mm (+/- 1mm)
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Katana 1100 (GSX1100F)
Type: BST34SS
Main Jet
Cylinders #1 and #4: 112.5
Cylinders #2 and #3: 110
Main Air Jet: 0.6mm
Jet Needle
California: 5DL16
U.S except California: 5DL11
U.K: 5DL7-3
Needle Jet
California and U.K: P-0
All others: P-2
Pilot Jet
California and U.K: 42.5
All others: 32.5
Pilot Air Jet
California: 155
U.S except California: 135
U.K: 150
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Pilot Screw setting
U.S: Preset
1988-1990 U.K: Preset (2 7/16 turns out)
1991 on U.K: Preset (2 1/2 turns out)
Starter Jet (choke): 42.5
Float Height: 14.6mm (+/- 1mm)
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