S&S Cycle Replacement Cylinder Heads for 1984-1999 Harley-Davidson Evolution Engines and 1986-2003 Sportster Motorcycles - Manual (Page 5)

NOTE: 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 other.
E. Repeat checking and bending procedure for the
other rod.
3. Piston and Cylinder Fitting
NOTES:
●
For maximum piston and ring life, fit pistons using
appropriate close fit dimensions. Close fit requires strict
adherence to new engine break-in procedures.
● For immediate drag strip use, fit pistons using appropriate
loose fit dimensions. Attempt to break in rings and pistons
with 50 easy miles if possible. Piston and ring life will be
reduced when using loose fit dimensions.
Failure to follow instructions and perform required
clearancing, installation and/or break-in procedures correctly
may result in damage to pistons and/or other engine
components. S&S
® voids its guarantee if pistons are not
installed and/or broken in properly.
A. Measure piston across thrust face 90° to wristpin hole.
Make a series of measurements starting directly below
oil ring groove and ending at extreme bottom of skirt.
Use widest measurement to represent size of piston.
See Figure 3.
NOTE: All 3 1 ⁄
2
" and 3 5 ⁄
8
" bore pistons for S&S Super Stock ® cylinder
heads have barrel shaped skirts. As a result, largest diameter is
located
1 ⁄
4
" to 1 ⁄
2
" above extreme bottom of skirt. See Figure 3.
B. Determine size of cylinder. Refer to S&S piston fitting
instructions 51-1028 for the clearance specifications.
C. Bore and hone cylinder to size required for piston plus
proper desired running clearance. Use torque plates
torqued to 50 ft. lb. to simulate stresses in an
assembled engine.
NOTE: S&S recommends using a 220 grit stone during final
honing process. Using finer than 220 grit stones will result in
smoother cylinder wall finishes which do not provide sufficient
abrasion between cylinder wall, piston and rings nor sufficient oil
retention for proper lubrication required for break-in.
Insufficient cylinder wall lubrication during break-in process
may result in piston scuffing and damage to pistons, rings
and/or cylinders.
D. Thoroughly clean cylinders, pistons and all parts
required to reassemble engine. Use high grade lacquer
thinner on gasket surfaces.
● Some solvents, degreasers 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. Never
direct compressed air toward other people.
4. Rebalance Flywheels (883 & 1100 Harley-Davidson ®
Sportster ® models only)
This step applies to all Super Stock cylinder head installations
on Sportster
® 883 and 1100 engines.
NOTE: S&S Super Stock 3 1 ⁄
2
" and 3 5 ⁄
8
" bore matching pistons
are designed to replace stock 1200cc and 1340cc pistons and
S&S 92-2420 and 92-1900 series pistons without requiring
flywheel rebalancing. This also means that engines presently
equipped with 3
1 ⁄
2
" bore can be converted to 3 5 ⁄
8
" bore
without rebalancing. Rebalancing is required only when
converting 883cc and 1100cc stock bore Sportster
® engines to
3 1 ⁄
2
" or 3 5 ⁄
8
" bore.
When converting 883cc and 1100cc stock bore Sportster ®
engines to 3 1 ⁄
2
" or 3 5 ⁄
8
" bore, failure to rebalance engine will
cause engine vibrations possibly resulting in damage to
engine components.
A. Follow Harley-Davidson ® factory procedures outlined in
Harley-Davidson ® service manual for removing and
disassembling engine.
B. Rebalance flywheels.
NOTE: If engine is expected to be used under extreme
conditions, it is recommended that the connecting rods in
engines prior to 1989 be changed to Harley-Davidson
® part
#24275-86A or S&S 34-7800 as either of these assemblies is
stronger than early stock Harley-Davidson
® connecting rods.
CAUTION
Figure 3
CAUTION
WARNING
CAUTION
Dome
Deck
C C
B
A
A. Piston dome height.
B. Piston deck height.
C. Measure piston diameter on thrust face 90° from wristpin.
Largest diamete will be 1 ⁄
4
" to 1 ⁄
2
" from bottom piston skirt.
5