INTRODUCTION
4
1
⁄
8
" bore engine instructions often refer to procedures described
in other S&S
®
instructions or a Harley-Davidson
®
Service Manual.
These materials should be cross-referenced as necessary.
All 4
1
⁄
8
" bore engines are designed for frames that accept 1984-'99
big twin engines, and will fit stock Harley-Davidson
®
and similar
frames without modification.
S&S strongly recommends trial-fitting every engine before frame
is painted or powder coated.
Because the 4
1
⁄
8
" bore crankcase is
1
⁄
4
inch wider than stock, fit of
exhaust, rear brake master cylinder, and foot controls must be
closely checked when installing the 4
1
⁄
8
" bore engine. Some
components may require modification.
In some instances, brake master cylinder must be spaced out
from frame to clear crankcase. UNDER NO CIRCUMSTANCES
SHOULD MASTER CYLINDER OR BRAKE LINE BE ALLOWED TO
CONTACT EXHAUST PIPE IN FINAL INSTALLATION. Heat
transferred to brake fluid may expand and cause brakes to seize,
resulting in possible fire hazard and loss of control of motorcycle
with injury or death to rider and others.
IMPORTANT NOTES
●
Lubrication - S&S supplies Torco Engine Assembly Lube with
each engine. It should be used as specified in following
instructions. While other brands of assembly lube are
acceptable, other lubricants are not. In no instance should an
aerosol lubricant be substituted for assembly lube.
●
Engine tuning - Ignition timing and carburetor jetting
are responsibilities of the customer. If not thoroughly
familiar with these procedures, he should contact a
professional mechanic.
Incorrect ignition or carburetor tuning can cause extensive
engine damage not covered under warranty.
●
Powder coating and polishing - While S&S does manufacture
some powdercoated engines, it does not recommend having
engine parts powdercoated or otherwise modified
elsewhere. Many such procedures leave abrasive residues
which are difficult to remove completely. Also, powder
coating is cured at high temperatures that can change the
strength characteristics of some metals.
Glass bead and polishing residues are abrasive and can be
difficult to remove from recesses and small passages.
Abrasive residues can cause oil contamination and extensive
engine damage. Engine damage caused by powder coating,
polishing, glass bead blasting, or other modification will not
be covered under warranty.
ASSEMBLY
NOTE - While S&S has made every effort to insure that parts are
correct, it is the engine builder’s responsibility to confirm fit and
finish of all parts provided with engines prior to assembly. Parts
are deburred at S&S and usually require no further preparation,
but must also be inspected by installer. Individual parts should not
be removed from protective plastic wrappers until needed. After
removal from plastic, it is imperative that parts be thoroughly
cleaned and dried, preferably with compressed air. When
present, rust preventative must be completely removed.
Additionally, gaskets must be closely inspected for particles that
could become dislodged and damage engine. If assembly of
engine must be interrupted, seal openings and cover engine with
plastic to protect from destructive contaminants.
2
WARNING
CAUTION
Big Twin Bearing Race
Diameter
Pinion Shaft Bearing Diameter
1.2498 - 1.2500
1.2500 -1.2502
1.7511 to 1.7513
Red
S&S
®
#31-4017
H-D
®
#24628-87A
Blue
S&S
®
#31-4018
H-D
®
#24643-87A
1.7509 to 1.7511
Blue
S&S
®
#31-4018
H-D
®
#24643-87A
White
S&S
®
#31-4005
H-D
®
#24626-87A
1.7507 to 1.7509
White
S&S
®
#31-4005
H-D
®
#24626-87A
Green
S&S
®
#31-4016
H-D
®
#24628-87A
Bearing Race Diameter
Minus Pinion Shaft
Bearing Diameter
Bearing Color Code
.5005 to .5009
Green
S&S
®
#31-4016
H-D
®
#24628-87A
.5007 to .5011
White
S&S
®
#31-4005
H-D
®
#24626-87A
.5009 to .5013
Blue
S&S
®
#31-4018
H-D
®
#24643-87A
.5011 to .5015
Red
S&S
®
#31-4017
H-D
®
#24641-87A
Chart 1
Chart 2
S&S
®
Pinion Shaft Main Bearing Fitting Charts
CAUTION
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
original equipment parts or that they are equivalent to the corresponding Harley-Davidson
®
part number shown.
Pinion Bearing Roller Diameter
Bearing Color Code
Roller Size
Total
Green
S&S
®
#31-4016
H-D
®
#24628-87A
.2502”
.5004”
White
S&S
®
#31-4005
H-D
®
#24626-87A
.2503”
.5006”
Blue
S&S
®
#31-4018
H-D
®
#24643-87A
.2504”
.5008”
Red
S&S
®
#31-4017
H-D
®
#24628-87A
.2505”
.5010”
