Instruction sheet No. 3000
Revised 4-6-99
S&S Cycle, Inc.
Copyright ©,
1980, 1984, 1988, 1991, 1999
14025 County Hwy. G
Box 215
Viola, Wisconsin 54664
by S&S Cycle, Inc.
All rights reserved. Printed in the U.S.A.
Phone 608-627-1497
Fax 608-627-1488
Customer Service - sscust@sscycle.com
Technical Assistance - sstech@sscycle.com
3"/3-3/16" Bore Sportster Stroker Kit Installation Instructions
OHV Engines 1957 and 1985
Safe Installation and Operation Rules:
Before installing your new S&S stroker kit it is your responsibility
to read and follow the installation procedures in these instructions
and follow the basic rules below for your personal safety.
● Gasoline is extremely flammable and explosive under certain
conditions and toxic when breathed. Do not smoke. Perform
installation in a well ventilated area away from open flames or
● If compressed air is used during installation, be particularly careful.
Compressed air and particles dislodged from using compressed
air are harmful to eyes and body. Wear protective goggles, and
always direct air stream away from body parts such as hands and
eyes and other people near you.
● When using solvents, degreasers and other chemicals during
cleaning and installation, read manufacturer's instruction label for
proper use. Exposure of some chemicals to skin, eyes and/or other
body parts may be harmful. Many items are flammable and present
a fire hazard. Use in well ventilated area and wear protective
clothing when using them to avoid personal injury.
● If motorcycle has been running, wait until engine and exhaust
pipes have cooled down to avoid getting burned before performing
any installation steps.
● Before performing any installation steps disconnect battery to
eliminate potential sparks while working on electrical components.
● Read instructions thoroughly and carefully so all procedures are
completely understood before performing any installation steps.
Contact S&S with any questions you may have if any steps are
unclear or any abnormalities occur during installation or operation
of motorcycle.
● Consult an appropriate authorized H-D service manual for correct
disassembly and reassembly procedures for any parts other than
those outlined in these instructions.
● Use good judgement when performing installation and operating
motorcycle. Good judgement begins with a clear head. Don't let
alcohol, drugs or fatigue impair your judgement. Start installation
when you are fresh.
● Be sure all federal, state and local laws are obeyed with the
● Be sure all fuel lines, supply and overflow, are routed correctly
and fuel line clamps are in place and tightened. Lines must not
contact exhaust pipes or other extremely hot surfaces where they
could melt or leak and catch fire.
● Before starting engine and riding motorcycle, be sure throttle
opens and closes smoothly. Turn handlebars to left and test throttle.
Then, turn bars to right and test throttle. To avoid possible loss of
control of motorcycle and potential personal injury to yourself or
others due to throttle sticking in open position, throttle must work
smoothly and return to a fully closed position when hand is removed
from throttle grip.
● Motorcycle exhaust fumes are toxic and poisonous and must not
be breathed. Run motorcycle in a well ventilated area where fumes
can dissipate.
Statements in this instruction sheet preceded by the following
words are of special significance:
Means there is the possibility of injury to yourself or others.
Means there is the possibility of damage to the engine or
Other information of particular importance has been placed in
italic type.
S&S recommends you take special notice of these items.
All S&S parts are guaranteed to the original purchaser to be free of
manufacturing defects in materials and workmanship for a period
of six (6) months from the date of purchase. Merchandise that fails
to conform to these conditions will be repaired or replaced at S&S’s
option if the parts are returned to us by the purchaser within the 6
month warranty period or within 10 days thereafter.
In the event warranty service is required, the original purchaser must
call or write S&S immediately with the problem. Some problems can
be rectified by a telephone call and need no further course of action.
A part that is suspect of being defective must not be replaced
by a Dealer without prior authorization from S&S. If it is deemed
necessary for S&S to make an evaluation to determine whether the
part was defective, a return authorization number must be obtained
from S&S. The parts must be packaged properly so as to not cause
further damage and be returned prepaid to S&S with a copy of the
original invoice of purchase and a detailed letter outlining the nature
of the problem, how the part was used and the circumstances at
the time of failure. If after an evaluation has been made by S&S
and the part was found to be defective, repair, replacement or refund
will be granted.
(1) S&S shall have no obligation in the event an S&S part is modified
by any other person or organization.
(2) S&S shall have no obligation if an S&S part becomes defective
in whole or in part as a result of improper installation, improper
maintenance, improper use, abnormal operation, or any other misuse
or mistreatment of the S&S part.
(3) S&S shall not be liable for any consequential or incidental
damages resulting from the failure of an S&S part, the breach of
any warranties,the failure to deliver, delay in delivery, delivery in
non-conforming condition, or for any other breach of contract or
duty between S&S and a customer.
(4) S&S parts are designed exclusively for use in Harley-Davidson
motorcycles. S&S shall have no warranty or liability obligation if an
S&S part is used in any other application.
Installation of an S&S Sportster Stroker Kit is
comparatively easy and can be performed by any
average Harley-Davidson repair shop equipped to do
complete engine overhauls. No special tools other than
those used in normal overhaul operations are required.
⁄16" Diameter hole
Line A
Read instructions thoroughly before starting work.
When they are completely understood proceed with
Line B
Installation Steps:
1. Crankcase Alignment & Cylinder Mounting Studs
2. Lower Oil Return Holes (All)
3. Crankcase and Piston Skirt Clearancing (All)
4. Connecting Rod Preparation (All)
5. Lower End Assembly (All)
6. Connecting Rod Alignment (All)*
7. Breather Timing (All)
8. Piston to Valve Clearancing (All)
9. Final Top End Assembly and Engine Installation
10. Timing, Carburetion, Exhaust, Gearing & Break-in
*NOTE - S&S recommends that engine builder consider
performing some steps during initial engine
disassembly. Breather timing check requires that most
components be assembled, and performing check upon
disassembly may save reassembly and cleaning time.
While some or all related parts concerned in connecting
rod alignment check may be replaced, it is helpful to
check original parts combination and note
discrepancies which may alter installation of new parts.
⁄16" Diameter hole
Line A
Figure 1
1. Crankcase Alignment and Cylinder Mounting
Studs (All)
NOTE - Some H-D crankcase base gasket surfaces
on which cylinders are positioned do not align properly.
This usually occurs when crankcase halves used are
from different crankcase assemblies and were not
paired and machined together at Harley-Davidson. It
is recommended to check for crankcase misalignment
even if crankcase halves are correctly matched to
prevent potential oil leaks and other mechanical
CAUTION - Mismatched gasket surfaces due to
improperly aligned crankcase halves may cause
unwarranted stress on cylinder base flanges which
could result in cylinder flange failure.
A. Clean cases thoroughly and assemble both
cases without flywheels and tighten all case
bolts as in final assembly.
B. Place straight edge across base gasket surface.
See Picture 1.
C. If any misalignment exists, remove cylinder
base studs and place masking tape over cam
and mainshaft bearings to keep chips out.
D. Place cases squarely in mill and take minimum
cut necessary to clean up.
E. If stock cylinder studs are to be used, reinstall
to original height. If studs are provided in kit,
install to height that equals: thickness of cylinder
base flange, plus base gasket, plus cylinder
base plate, plus washers, plus base nut. Use
Loctite Stud and Bearing Mount to secure studs.
Picture 1
drill ⁄ hole
" diameter hole
drill 3⁄32" diameter
Figure 2
2. Lower Oil Return Holes
Sportster cylinder oil return holes must be lowered in
those stroker conversions where oil ring crosses stock
oil return hole. This is necessary to prevent oil from
returning above oil ring which will cause engine to
smoke. Several lowering methods have been used
successfully but rather than give them all, we decided
to provide the one that requires the fewest special tools
and materials.
● Oil rings will usually touch and/or cross oil return
holes with installation of stroke 4 7⁄16” or longer. Strokes
shorter than 4 7⁄16” do not require this step.
● Method given below was tried as an experiment when
we installed an S&S 4 5⁄8” stroker kit in our 1972 test
Sportster. All steps axcept 8 and 9 were performed.
Picture 2
Object was to see if engine would smoke and use
excessive oil which it did not. Several customers have
also reported similar successes when leaving stock holes
open. Based upon our test results and these customer
reports, we feel relatively confident in recommending
that stock oil return holes be left open even though we
have tried it on only one test engine and cannot
guarantee that it will work in all instances. If you decide
to try leaving the stock oil return holes open, perform all
of the following steps except 8 and 9.
For strokes 4 7⁄16” and longer, perform following steps:
A. Place cylinder with head gasket surface down on
bench. Lay out lines “A” on cylinder base gasket
surface so they are directly above centers of old
oil return holes which exit into cylinder bore. See
Figure 1.
B. Lay piece of 1⁄8” thick material against cylinder
spigot 90° to lines A and scribe lines "B".
C. Centerpunch points where lines A and B
D. Drill 3⁄ 16” diameter hole at each point
perpendicular to gasket surface to meet
passage coming from cylinder head. Be careful
not to break drill when breaking into existing
passage as holes may be slightly misaligned
and drill may tend to grab.
E. Centerpunch corners where lines A intersect
spigot. See Figure 2.
F. Drill 3⁄32” diameter hole at each point at 60° angle
into cylinder bore.
G. Enlarge 3⁄32” holes from inside cylinder bore with
⁄16” diameter drill.
H. Braze or weld old oil return holes shut.
Picture 3
NOTE - Be sure person who does work knows how to
work with cast iron as cylinders may crack or develop
hard spots if not done properly
Repeat step D to remove braze or welding
material that may be obstructing oil return
J. Blow air through passages to remove chips, etc.
B. Assemble pistons without rings on their proper
connecting rods, and place connecting rods on
crankpin. Installation of wristpin button is not
CAUTION - Dirt, filings, etc. left in oil return
passageways may circulate in oil damaging other
parts possibly causing engine failure.
● Some solvents, degreasers, gasoline and other
chemicals are harmful to skin, eyes and other body
parts. Many items are flammable and present a
fire hazard. Read manufacturer's instruction label
for proper use. Use in well ventilated area and wear
protective clothing when using them to avoid
personal injury.
● Compressed air and particles dislodged by
compressed air are harmful to eyes and body. Wear
protective goggles when using compressed air and
always direct air stream away from body parts such
as hands and eyes and other people near you.
3. Crankcase and Piston Skirt Clearancing (All)
NOTE - If pistons have piston to piston clearance
notches ground on thrust face edges, place notches
toward center of engine. Consult piston installation
instructions included with pistons for proper piston
direction placement.
C. Install both cylinders and secure each with one
NOTE - If base plates are to be used, be sure they are
in place.
D. Rotate flywheel until rods contact areas to be
clearanced. Note angle that must be filed. See
Picture 4.
E. Disassemble cylinder and connecting rods and
file crankcase and cylinder spigot for clearance.
NOTE - A minimum of 1⁄16” clearance is required.
F. Reassemble and check clearance.
G. This procedure must be done for both
crankcase halves.
Connecting Rod Clearance
Pictures 2 and 3 show areas to be checked and/or
clearanced for connecting rod to crankcase contact.
Procedure to check these points is performed as
A. Mock up right side flywheel in crankcase half
with mainshaft and crankpin installed with
bearings, etc. in place.
CAUTION - Insufficient clearance between
connecting rods and crankcases will cause contact
and damage to components.
Picture 4
Picture 5
Piston Clearance
Pistons must be clearanced to avoid contact with each
other and with flywheels. See Pictures 5 and 6.
installed with larger intake pockets toward center of
engine. Be sure to file material from skirt on intake
side of piston.
E. Reassemble and check clearance.
Grind stroke
clearance in
this area
Piston to Flywheel Clearance
A. Perform steps A through C in "Connecting Rod
Clearance" above.
B. Rotate flywheel to position where front piston
is closest to flywheel. See Picture 6.
C. Check clearance between piston and flywheel.
NOTE - A minimum of 1⁄16” clearance is required.
Grind four oil
grooves on both
sides of forked rod
Figure 3
Piston to Piston Clearance
A. Perform steps A through C in "Connecting Rod
Clearance" above.
B. Rotate flywheel to position where pistons are
closest to each other. See Picture 5.
C. Check clearance between pistons.
NOTE - A minimum of 1⁄16” clearance is required.
D. Disassemble cylinders and pistons, and
carefully file edge of piston skirts until clearance
is obtained.
Note - Intake valve pocket in piston dome are larger
than exhaust valve pocket. Be sure pistions are
Picture 6
D. Disassemble cylinder and piston, and carefully
file piston skirt until clearance is obtained.
E. Reassemble and check clearance.
F. Repeat procedure for rear piston.
NOTE - Material removed from pistons for clearancing
purposes will not adversely affect flywheel balance.
Some S&S kits utilize flywheels with diameters smaller
than stock (stock Sportster flywheels are 7 7⁄8"). This is
done to maximize piston skirt length. Our experience
has shown that while it is better to build up flywheel
scraper, it is not absolutley necessary.
CAUTION - Insufficient clearance between pistons
and pistons and flywheels will cause contact and
damage to components.
4. Connecting Rod Preparation (All)
NOTE - If S&S connecting rods are used, follow
instructions that accompany rods since rod preparation
below has already been done.
If S&S rods are not used, perform following steps:
A. To insure adequate oil on sides of rods and
matching thrust surfaces of flywheels, S&S
recommends that four grooves be ground on
each side of both front and rear connecting rods.
See Figure 3. Make these grooves .020" to
.030" deep and .030" to .040" wide and should
be ground 90° from each other. After making
grooves, remove all sharp edges and burrs with
emery cloth.
B. With rods assembled, measure distance
between rods at closest points in wristpin holes.
If measurement exceeds 2.950" as shown in
Figure 3, grind female rod at points where male
rod makes contact to achieve sufficient
NOTE - Rods clearanced to this dimension provide
adequate clearance for strokes up to and including 5".
Do not remove any more material than is necessary to
obtain required clearance.
CAUTION - Inadequate clearance between rods or
too much clearancing on rods will cause
unwarranted stress on connecting rods, rod
bearings, pistons, etc. resulting in possible failure
of one or all aforementioned parts.
C. Thoroughly clean all parts to remove dirt, filings, etc.
CAUTION - Burrs, dirt, filings, etc. left on
connecting rod components may circulate in oil
damaging other parts possibly causing engine
Picture 7
5. Lower End Assembly (All)
● S&S Sportster flywheels with serial numbers that
start with a letter or those numbered 1670 or higher
are made from closed die, heat treated, steel forgings.
They do not have connecting rod thrust washers like
earlier S&S flywheels, because present flywheel
material is harder than thrust washers previously used.
● S&S flywheels come with three timing marks. An
"F” stamped by a mark means front cylinder, an "R”
means rear cylinder and a “TF” means top dead center
front cylinder. When front or rear mark is placed in
center of timing hole it means that that cylinder is timed
at 40° before top dead center. We recommend that
stroker Sportster engines be timed at 40° initially. See
Step 12, "Ignition Timing".
● Usually S&S flywheels are balanced before leaving
our facility. Some customers prefer to do their own
balancing or to have another balancing shop do the
work for them. This is acceptable in most cases.
However, we have had some bad experiences with
dynamically balanced flywheels that have forced us to
void our guarantee if flywheels have been balanced in
this fashion.
CAUTION - Flywheels assembled improperly prior
to being dynamically balanced may sustain
irreversible damage to mainshaft and crankpin
tapers during actual balancing. S&S voids its
guarantee if flywheels have been balanced in this
● Assembling flywheels, mainshafts and connecting
rods can be easy or difficult. Degree of difficulty is
determined by builder technique and parts at his
disposal. While S&S flywheels have been noted for
their easy truing qualities, they can be difficult to true if
a defective part is used that should have been detected
before assembly.
● Cleaning parts prior to and during assembly and
keeping parts clean after final assembly is imperative
to minimize contaminants that may circulate in oil and
shorten engine life. Use cleaning agents that do not
leave harmful residues, and be sure to read and follow
manufacturer's instruction label before use. Use drills
and compressed air to clean all oil passageways of
dirt, filings, etc. whenever possible.
● Some solvents, degreasers, gasoline and other
chemicals are harmful to skin, eyes and other body
parts. Many items are flammable and present a
fire hazard. Read manufacturer's instruction label
for proper use. Use in well ventilated area and wear
protective clothing when using them to avoid
personal injury.
● Compressed air and particles dislodged by
compressed air are harmful to eyes and body. Wear
protective goggles when using compressed air and
always direct air stream away from body parts such
as hands and eyes and other people near you.
Perform following steps when assembling flywheels:
A. Thoroughly clean all parts to be used. This
includes mainshafts, main bearings, connecting
rods, rod bearings, crankpin nut retainers and
screws if they are to be used, keys and
flywheels including tapers and keyways.
CAUTION - Burrs, dirt, filings, etc. left on flywheel
assembly parts may circulate in oil damaging other
parts possibly causing engine failure.
NOTE - S&S recommends to tighten nuts very tight.
We use a 3⁄4”drive breaker bar and a five foot piece of
pipe when assembling flywheels.
B. Check both mainshafts between centers for
taper surface to bearing surface concentricity.
Make sure centers on shafts are clean
beforehand. If tapers and bearing surfaces are
concentric with each other and with center, then
truing will be easier. See Picture 7.
After right side flywheel, pinion shaft and
crankpin are assembled, blow air through pinion
shaft oil feed hole to check for blockage.
NOTE - Current H-D specs. allow maximum of .001"
runout between taper and bearing surfaces. We feel
this is too much and prefer to see .0003" or less with
an absolute maximum of .0005". S&S shafts are .0003"
or less.
C. Inspect keyways and oil holes for burrs in
flywheels and remove if necessary.
D. With key in shaft, insert into respective tapered
hole in flywheel and check to see that key does
not bottom in groove. If key bottoms out, file
flat side of key, not rounded side, until shaft with
key in place fits in flywheel without bottoming
out. Check crankpin and crankpin key also.
E. Reclean mainshaft tapers, crankpin and
flywheel tapers with lacquer thinner.
F. Assemble mainshafts in respective flywheels.
Coat taper and threads of each shaft with
green Loctite RC 609 or Omni Fit 1730 during
assembly. Install crankpin in camside flywheel
using Loctite also. Tighten all nuts to at least
factory torque specs minimum. When S&S
shafts are used, follow instructions included
with them.
Picture 8
CAUTION - Partially or completely blocked oil feed
passageways may cause irreversible damage to
bearings and other engine components.
G. Measure width of female rod on crankpin end.
See Picture 8. Measurement should be 1.481”
to 1.483".
H. Assemble left and right flywheels and
moderately snug nuts. Do not worry about them
being true. Measure distance between
connecting rod thrust pads. See Picture 9.
NOTE - S&S recommended rod side play is .015" to
Rod Side Play Equals
(Distance from Pad to Pad) - (Female Rod Width)
CAUTION - Incorrect connecting rod side play may
cause excessive rod side thrusting and potential
damage to rods, flywheels and other engine
If difference is less than .020", female rod must
be ground on sides as final tightening will pull
wheels closer together. Rod side play
diminishes about .015" when crankpin nut is
final tightened. Take equal amounts off each
side if amount to be removed is more than .010".
Picture 9
If there is no rod side play try different crankpin.
If rod side play is more than .035", try different
crankpin. We have run side play of as much as
.045" without serious consequences. If side
play is excessive and different crankpins do not
correct problem, contact us.
NOTE - If material is removed from sides of female
rod, overall width of bearing cages must be reduced
so bearings and cages are free to float with rods without
contacting flywheel thrust pads. Bearing cage side
clearance of .008 to .020 less than rod width is
CAUTION - Connecting rod bearing and cage
assemblies that are wider than female rod may
become damaged upon contact with flywheel thrust
pads. Damaged rod bearing assemblies and/or
foreign material from damaged components
circulating in oil could cause further destruction
and possible failure of other engine parts.
Finish assembling flywheels and rods.
Following above procedures will help diagnose
problem if difficulty should arise.
6. Connecting Rod Alignment (All)
After flywheel assembly is installed in crankcases, rods
must checked for straightness. S&S Rod Checking
Pin, Part #53-0002, was designed to help perform this
procedure. It may also be necessary, to fabricate a
rod bending tool as illustrated in Figure 4.
NOTE - The purpose of this procedure is to correct for
machining tolerance discrepancies in components
which may lead to pistons not running true in cylinder
.510"-.520" Wide Slot
1 1/8"
1 1/4 "
Figure 4
Picture 10
bores. While rods may be straight and true, it is
sometimes necessary, to bend them to correct for these
machining discrepancies. Do not bend rod by using
tool in wristpin hole as this method may distort wristpin
bushing. We also feel that using a piston in lieu of a
checking pin may prove inaccurate due to variations in
lengths of piston skirts from one side of piston to the
CAUTION - Pistons which do not run true in cylinder
bores may cause excessive connecting rod side
thrusting. This in turn may lead to premature ring,
piston, connecting rod and rod bearing wear and
eventual failure of these parts.
Checking Pin Procedure
A. Insert checking pin into wristpin hole. Place strips
of paper between checking pin and crankcase
cylinder gasket surface and apply slight
downward pressure to wristpin end of rod by
rotating flywheels. Pull papers out slowly. Drag
on papers should be equal.
B. Rotate flywheels in opposite direction until
checking pin contacts cylinder gasket surface
again. Repeat procedure to rod again. If drag
on papers is equal no bending is required. If
one paper is loose, use rod bending tool to
tweak rod in direction of loose paper and
recheck. See Picture 10.
C. Repeat checking and bending procedure for
other rod.
Visual Procedure
A. Install pistons on rods without rings or wristpin
buttons. Bolt cylinders with gaskets in place.
B. Move piston tight towards camside of engine.
C. Turn engine over in normal direction of travel 2 or
3 revolutions and observe piston during process.
D. Move piston towards driveside of engine and
repeat Step C. If inaccuracies are present due
to machining variations in cases, cylinders or
pistons, top land of piston deck will appear closer
to cylinder wall at one point around
circumference. This means that piston is cocked
in cylinder bore and can be corrected by bending
rod in opposite direction. Figure 5 shows an
exaggerated side view of this condition.
E. Repeat Steps B to D for other cylinder.
NOTE - All engines should be checked upon
disassembly for incorrect piston alignment. This applies
to those which are receiving new pistons as well as those
being completely rebuilt. Observe pistons for wear spots
on sides above top compression ring. If one side near
wristpin is worn clean while side opposite is carboned
up, then piston was not running straight and true in
cylinder bore. Piston will also generally show diagonal
wear pattern on thrust faces of skirts and possibly signs
of connecting rod to wristpin boss contact inside piston.
We feel that not enough emphasis is given to checking
piston alignment in cylinder bore. Proper piston
alignment means connecting rods will thrust to sides
less minimizing added stress on pistons, rings, rod
bearings and other related parts.
7. Breather Timing (1957 to 1976)
● Instances of smoking in early Sportsters led us to
believe that crankcase breather timing was incorrect.
Examination of several engines has shown that
breather timing varies from engine to engine because
of differences in overall width of crank assembly which
changes position of pump drive worm gear on pinion
shaft with respect to pump gear. When engine is
disassembled, breather timing should be checked and
set to XLR specifications.
● Breather timing should be set so breather valve
opens when front piston is at 20° to 25° after top center
(ATC) position, and closes when front piston is at 85°
to 90° after bottom center (ABC) position.
● Crankcase oil scavenging can be greatly improved
on 1957 to 1971 engines by converting to 1972 and later
style breather parts combination. If your engine is 1971
or earlier, we strongly recommend purchase of 1972 and
later pump breather gear, H-D part #26331-72 and
corresponding gear retainer lock ring, H-D part #11002.
These parts are used in place of early pump breather
gear, part #26331-60, because slot in early version is
too wide and requires the removal of too much material
from pump body to achieve desired results. When later
parts are used in early pump, scavenger gear, part
#26315-62, must be installed with flat side of gear facing
retainer lock ring.
To check and correct crankcase breather timing,
perform following steps:
A. Before installing oil pump, turn pump gear
counterclockwise until sleeve hole in gear aligns
with slot in pump body. Place .002" shim in
opening and reverse gear until tight. Scribe
mark across pump gear sleeve and pump body
at small timing notch on top edge of body. See
Figure 6.
Scribe mark
Breather gear just
starting to open
Enlarge closing
side only
Figure 5
Figure 6
NOTE - Pump gear sleeve is very hard and scribing
mark may be difficult. It may be advantageous to coat
top ring of sleeve just below teeth with Dykem Blue to
make marking easier.
B. Install and time pump in normal manner as in
final assembly.
C. Install degree wheel on sprocket shaft, and
position pointer at 0° when front piston is at top
dead center (TDC) position.
D. Rotate front piston to 25° ATC. Be sure oil pump
drive gear is firmly butted against shoulder on
pinion shaft.
E. If scribe mark on pump gear is to left of scribe
mark on body, grind material off engine side of
pump drive gear to allow it to move farther onto
shaft until scribe marks line up. If scribe mark
is to right, place shim between pump drive gear
and pinion shaft shoulder to line up marks. Big
Twin cam thrust washers, H-D part #25550-36,
can be used for this purpose, but are marginal
because they fit pinion shaft poorly. For a better
fit we fabricate our own washers to exact size.
F. Rotate crankshaft so front piston is at 85° ABC
(after bottom center).
G. Make a second scribe mark on pump to align
with first scribe mark on body.
H. Remove pump and carefully grind or file slot
wider in body towards cam cover until it closes
at second scribe mark. Proceed with caution.
Do not remove more material,than absolutely
necessary. If unsure, contact S&S before you
make a mistake.
CAUTION - Improper breather timing causes poor
oil scavenging from flywheel cavity and incorrect
crankcase air pressure. These conditions may
cause unwarranted engine oil leaks around gaskets
and seals and probable oil burning due to oil blow
by past piston rings. Removal of excessive material
from slot opening is irreversible and damage to
body may result.
During final assembly, place oil pump drive gear
on pinion shaft, and time pump in normal
fashion. If material was removed from flywheel
side of oil pump drive gear, it may be necessary
to shim between pump drive gear and pinion
NOTE - Pinion gear must be flush with or extend out
slightly past splines on pinion shaft so pinion gear end
play shim does not contact pinion shaft splines instead
of pinion gear.
● Improper pinion gear spacing may cause
incorrect breather timing and poor oil scavenging
from flywheel cavity. This condition may cause
unwarranted engine oil leaks around gaskets and
seals and probable oil burning due to oil blow by
past piston rings.
● Improper pinion gear spacing may cause
unwarranted contact between pinion gear shim and
pinion shaft splines resulting in damage to gear
cover and/or other engine components.
J. Check clearance between pinion gear and cam
cover bushing. Recommended clearance is
.005". Place shim between pinion gear and
gear cover. H-D shims, part #18268-48, are
.015" thick each and may be used for this
8. Piston to Valve Clearancing (All)
NOTE - All valve spring spacing, rocker arm to collar
and rocker arm to rocker cover clearancing must be
done before piston to valve clearancing can be
S&S pistons have sufficient valve clearance when used
with most street high performance cams. However,
we recommend that valve clearancing be checked if
other than stock cam is used.
Check piston to valve clearance in following manner:
A. Assemble engine with exception of cylinder
heads. Be sure valve pockets are positioned
Note - Larger intake pocket must be toward center of
B. Turn engine over until front piston is at top dead
center. Paint area around valve pockets on
pistons with machinist's blue.
C. Place valves in cylinder head leaving off springs
and retainers. Place head on cylinder and
secure with one bolt.
D. Lower valves until they contact piston. Rotate
valve marking painted area.
E. Remove head and check points of contact.
Valve should fit in recessed area machined in
piston dome.
NOTE - S&S recommends at least .060" clearance
around periphery of valve.
F. If insufficient clearance exists, remove piston
and grind valve pocket until head of valve fits
flush with proper clearance.
G. Repeat procedure for other cylinder head.
H. Spread layer of putty into valve pockets in both
I. Assemble cylinder heads and bolt assemblies
on cylinders with head gaskets in place. Install
pushrods and adjust to simulate final assembly.
J. Turn engine over in normal direction of travel
two complete revolutions.
K. Disassemble engine and check thickness of
putty in valve pockets.
NOTE - S&S recommends at least .060" clearance
between valve and piston valve pocket recess. While
.060 clearance is recommended minimum, it is
advisable to have .080 and up, if possible.
CAUTION - Insufficient clearance between piston
and valves may cause them to contact each other
during operation resulting in damage to piston and
valve train components.
L. If less than .060 clearance in any area exists,
grind area until proper clearance is achieved.
9. Final Top End Assembly and Engine Installation
NOTE - All previous steps must be completed.
We recommend installing cylinders without heads
bolted to cylinders for two reasons.
1. Combined weight of cylinder and cylinder
head makes assembly cumbersome and
hard to handle during installation.
2. Separate installation of cylinders and
cylinderheads permits more leeway for
adjustment to achieve a better manifold fit.
CAUTION - Installation of cylinders and cylinder
heads as assemblies may result in damage to rings
and piston assemblies. Improper intake manifold
fit may cause intake air leaks/improper fuel mixture
and resultant damage to engine components.
Final Assembly
A. Install and tighten cylinders, cylinder heads and
manifold as in standard assembly.
NOTE - Retighten cylinder base nuts and head bolts
as necessary after engine has been run.
B. Install engine in frame.
C. Install engine head mount.
NOTE - Stock head mount will be short if you are
installing S&S stroker kit with cylinder base plates. If
⁄16” thick or less plates are used, modify stock mount.
If plates thicker than 1⁄16” are used, install S&S extra
long head mount.
12. Timing, Carburetion, Exhaust, Gearing & Breakin (All)
Ignition Timing Notes
● See Step 5, "Lower End Assembly", for explanation
of S&S timing marks.
● S&S flywheels have timing marks that position
pistons at 40° before top center, same as stock, when
mark is in center of timing hole. Placing mark to right
side of hole or just entering hole advances timing almost
5°. Vice versa, if mark is just leaving hole, timing is
retarded almost 5°.
● Set ignition timing on all engines at 40°. On engines
equipped with vacuum operated advance mechanism,
set timing using Factory procedures.
● Ignition timing for engines with dual plugged heads
should generally be retarded 5-8° from the stock setting.
However, due to the large number of factors involved,
optimum ignition timing is impossible to accurately
predict and must be determined for each engine by
CAUTION - Improper ignition timing may cause
excessive engine heat which may damage pistons
and/or other engine components.
Carburetion Notes
● All S&S test engines have been run with S&S
carburetors. A Super E or Super G carburetor is
recommended for most strokers. Consult carburetor
jetting instructions for specific jetting recommendations.
● If another type carburetor is used, it must be made
to run rich enough so engine is not damaged. Other
carburetor types are a personal problem and we cannot
answer questions concerning them. It is best to call
carb manufacturer if you have any questions.
Exhaust Systems Notes
● To establish performance guidelines, S&S used 30”
long stock diameter drag pipes with good results. We
suggest you try them on these engines to establish a
baseline to compare with other systems.
● You might ask the manufacturer of the exhaust
system you are considering if he has had any
experience with S&S strokers. Many systems are made
for looks with little consideration given to performance.
Most stock systems and many aftermarket ones tried
are too restrictive for good performance. HarleyDavidson does offer a series of mufflers that can be
used with stock header pipes. These work very well in
most situations and offer an inexpensive alternative to
a new exhaust system. We prefer their tapered and
baloney cut styles.
Gearing Note
● Gearing depends on total weight of machine and
rider/s, size of engine, caming, exhaust system and
type of riding to be done. Most strokers are capable of
pulling more gear. We suggest you break engine in
with stock gearing to minimize lugging engine. After
engine is broken in you will have a better feel of its
potential and can change gearing accordingly.
● For those who wish to determine their final drive gear
ratio the formula is as follows:
Engine Revolutions Per One Revolution of Rear Wheel =
(Clutch sprocket*) x (Rear Wheel Sprocket*)
(Motor Sprocket* x (Transmission Sprocket*)
* Number of teeth on each sprocket
Break-In Procedure
CAUTION - Lugging or running engine prematurely
at high rpms may result in damage to pistons and/
or other engine components. S&S voids its
guarantee if engine is not broken in properly.
Break engine in using following procedure:
A. On initial engine startup, don’t just sit and idle
motor while you admire your work, or tinker with
minor adjustments. Heat buildup can be
B. First 50 miles are most critical for new rings
and piston break-in. Most engine damage will
initially occur during this period. Keep heat
down by not exceeding 2500 rpm. Vary speed.
Do not lug engine.
C. Next 500 miles should be spent running engine
no faster than 3500 rpm or about 50-55 mph.
Do not lug engine and continue to vary speed.
D. For balance of first 1000 miles, speed can be
run up to 60 to 70. Continue to run engine at
all different speeds including lower 40-45 mph
E. 1000 to 2000 miles—basically same
procedures as before. You can be a little more
liberal with rpm range. Avoid overheating
engine and putting any hard strain on it (drag
racing, trailer towing, sidecar operation).
F. 2000 miles and up—have fun!
NOTE - These engines must be broken in. They will
feel extremely strong, but resist the impulse to turn it
on. Break it in properly.