S&S Cycle Piston and Cylinder Kits for all 1986-up Harley-Davidson Sportster Models - Manual (Page 3)

c. Install Oil rings (See Figure 4, page 4)
1. Install the oil ring expander in the bottom groove of the
piston. The expander ring has a gold finish. Make sure
the ends of the expander ring are pointed upward and
butted together. Ends must not overlap (See Figure
1, above left). If the tips are overlapped, excessive oil
consumption will occur.
2. Bottom rail gap should be approximately 1.5" or 45° to
right of expander gap.
3. Top rail gap should be approximately 1.5" or 45° to left
of expander gap.
NOTE: Confirm that ends of expander do not overlap during installation.
Properly installed expander will appear larger than piston but will
compress when cylinder installed. In some cases, same expander is used
for several bore sizes. Oversize rings will not necessarily have a larger
expander.
d. Install compression rings observing the following:
• Second compression ring is cast iron regular or reverse
torsion type. This ring has a darker, charcoal gray finish.
• Top compression ring may be either moly faced or
chrome faced. This ring has a gray finish that is relatively
light in color.
• Any identifying “pip” marks, dots or oversize marks go to
top of piston.
• If ring has dot and inside diameter bevel, dot goes to top
of piston. See Figure 2, below.
• If ring has no dot but does have inside diameter bevel,
bevel goes to top of piston. See Figure 3, below.
• If ring has no dots and no bevel, it can go either way. See
Figure 4, below.
• Second compression ring gap should be 135° or
approximately 41⁄2" to right of oil expander gap. (See
Figure 5, next page).
• Top compression ring gap should be 135° or approximately
41⁄2" to left of oil expander gap. (See Figure 5 , next page)
CAUTION
Failure to remove burrs from piston ring ends after filing to size,
may cause engine damage. Incorrect installation of rings may
result in poor performance, excessive oil consumption or engine
damage.
5. Reassemble cylinders, cylinder heads, pushrods, and fuel system
according to procedures in the Harley-Davidson® service manual
or in instructions included with any aftermarket components
used. If high performance cams are installed, valve to piston
clearance must be checked.
NOTE: In all cases it is the engine builder’s responsibility to confirm
proper clearances when assembling an engine. This is especially critical
with performance components such as higher compression pistons and
high lift camshafts. In addition to clearances mentioned, .060" valve-to-
piston clearance must be confirmed.
CAUTION
Failure to establish proper clearances can result in severe engine
damage not covered under warranty.
6. Engine Break-In Procedure
NOTE: S&S® engine kits are designed for high performance and as such
are not as tolerant of inadequate break-in as a stock engine. Correct
break-in will assure longer engine life and will prevent unnecessary
engine damage. Engine damage caused by improper break-in is not
covered under the S&S warranty.
3
Picture 4
Figure 1
Incorrect orientation Incorrect overlap Correctly butted tips facing up
Figure 2 Figure 3 Figure 4