S&S Cycle Bore Big Twin Stroker Kit 1936–1999 3 7/16 - 3 1/2 User Manual
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S&S® FLYWHEEL ASSEMBLY TORQUE SPECIFICATIONS
Stock Harley-Davidson®
Shafts
S&S Shafts (Street) S&S Shafts (Racing)
Big Twin
Sprocket Shaft
290-320
400-450
450-500
Pinion Shaft
140-170
275-300
275-300
Crankpin Nut
180-210
350-400
450-500
Sportster® Model
Sprocket Shaft
100-120
340-360
350-400
Pinion Shaft—pre-1985
Sportster® Models
100-120
180-200
200-250
Pinion Shaft—1985-up
Sportster® Models
100-120
340-360
350-400
Crankpin Nut
150-175
290-310
350-400*
*Using S&S sprocket shaft nut on crankpin
S&S® Flywheel identiFication codeS For 1936-up big twin
Stroke code
Stroke
year code
engine year
Sprocket Shaft
pinion Shaft
crankpin type
diameter code
Flywheel diameter
1
43⁄8"
E
1936-'54
Stock
Stock
1941-'81
None
81⁄2" (Stock)
2
41⁄2"
L
1955-'71
Stock
Stock
1941-'81
A
83⁄8"
3
43⁄4"
AL
1972-Early '81
Stock
Stock
1941-'81
X
81⁄4"
4
5"
SE
1955-Early '81
S&S
Stock
1941-'81
5
41⁄4" (Stock 80")
BL
Late 1981-'99
Stock
Stock
1981-'99
6
45⁄8"
SL
Late 1981-'99
S&S
Stock
1981-'99
9
Special order
SF
1999-up
Press In
Press In
Press In
12
51⁄4"
SG
S&S 41⁄8" Bore
Press In
Press In
Press In
13
31⁄2" (Stock 61")
SM
1995-'99 EFI
Press In
S&S
1981-'99
14
331⁄32" (Stock 74")
Y
74/80 Indian®
Stock
Stock
Stock
16
51⁄8"
17
4"
18
35⁄8"
19
41⁄8"
TA
37⁄8"
Titan Special
TB
4.450"
FLYWHEEL IDENTIFICATION
Style, stroke, and diameter of S&S® flywheels can be determined by examining the serial number which is stamped on the rim of both flywheels
in the set. Usually the flywheel serial number can be read through the timing plug hole of an assembled engine. Press-together flywheel serial
numbers are stamped on the inside rim of S&S flywheels. A cylinder must be removed in order to read serial number.
S1234-3 SLX
Year of
Manufacture
Engine Style
Flywheel
Diameter
Serial Number
Flywheel Stroke
All reference to Harley-Davidson® part numbers is for identification purposes only. We in no way are implying that any of S&S® Cycle’s products are origi-
nal equipment parts or that they are equivalent to the corresponding Harley-Davidson® part number shown.