Caution warning caution caution caution – S&S Cycle Replacement Cylinder Heads for 1984-1999 Harley-Davidson Evolution Engines and 1986-2003 Sportster Motorcycles User Manual

Page 6

Under extreme conditions that exist in racing, early stock
connecting rods may fail causing damage to the engine.

Under extreme conditions as in a racing application, early stock
connecting rods may fail causing the engine to inadvertently
seize possibly causing loss of control of the motorcycle.

Reassemble bottom end using Harley-Davidson

factory

service procedures.

Install Pistons, Cylinders and Heads

Install cylinder base gaskets provided dry. Be sure
gaskets match cylinder base line-up dowels and oil
return passageways.

Install pistons on rods without rings and wristpin clips.

Slip cylinders in place over cylinder studs and pistons.

While applying pressure to cylinders, rotate flywheels in
normal direction of travel for at least one complete
revolution. Note if there is any resistance or contact
between pistons at any point in rotation. If contact or
resistance occurs, it must be diagnosed and corrected.

NOTE: Since it is nearly impossible to anticipate every possible
engine combination, it is the engine builder's responsibility to
check for proper running clearances. S&S

considers checking

and establishing all running clearances as standard engine
building practice that must be performed during engine
assembly. Engine failure due to improper clearances between
moving parts is not covered under warranty.

Contact between moving engine components may cause
damage or destruction of the parts involved and produce
abrasive particles which may cause damage or premature
wear to other engine components.

While applying pressure to cylinders, rotate flywheels so
front piston is positioned at top dead center. Note
where piston deck (See Figure 3 on page 5) is
positioned in relationship to head gasket surface. Most
stock Harley-Davidson

big twin and S&S engines should

have the top surface of the piston flush with or slightly
below the top surface of the cylinder (with a .020" thick
cylinder base gasket in place). After installing heads,
there should be .045" piston-to-head clearance at TDC
when using S&S heads, or .0625" clearance when using
stock heads. The clearance is provided by the thickness
of the head gasket used.

NOTES:
●

All S&S cylinder head kits are supplied with .045" thick head
gaskets, because this clearance promotes better combustion
chamber turbulence and flame travel. If the .045" head
gaskets are used with other cylinder heads, piston to head
and valve to piston interference may occur.

●

S&S kits for use with cylinder heads other than S&S are
supplied with .0625" thick gaskets. If the .0625" gaskets
are used with S&S heads, performance may suffer.

Insufficient clearance between piston domes and cylinder
heads or piston domes and valves will cause damage to
pistons, heads and/or valves. It is the engine builders
responsibility to check for adequate clearance regardless of
head and gasket combination.

Repeat procedure to check rear piston to cylinder gasket
surface relationship.

Install piston rings and wristpin clips per S&S piston
instruction sheet 51-1028.

Coat piston skirts with engine oil and install cylinders.

Spin each head bolt down on its respective stud to be
sure threads are clean and free of contamination.

Install head alignment dowels in cylinder. (Do not re-use
any dowels that are damaged, or have flanges or an O-
ring groove machined into them.)

Place head gaskets onto cylinder and over head
alignment dowels.

If the gasket fits close to the dowel pin and there is not
room for an O-ring, do not install an O-ring.

If there is room for an O-ring, install one O-ring over
each dowel per the note below.

NOTE: There are two sizes of alignment dowel O-ring available:
.070" diameter O-rings are to be used with .045" thick gaskets.
.0825" diameter O-rings are to be used with .0625" thick
gaskets.

Using thin O-rings with thick gaskets or thick O-rings with
thin gaskets may cause oil leaks or possible ruptured head
gaskets around line-up dowels due to incorrect O-ring
compression.

L. Ensure that the head gaskets and O-rings (if used) are

correct for the application, then remove them and
carefully clean head and cylinder gasket surfaces with
lacquer thinner or equivalent. Gaskets are to be
installed clean and dry. Do not use gasket sealing
compounds on cylinder head gaskets.

CAUTION

WARNING

CAUTION