S&S Cycle Sidewinder 3 5/8 Big Bore Cylinders for 1936–1999 Big Twins - Manual (Page 25)

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Ring Installation
1. Piston ring widths have changed on some piston series from time to time. It is recommended that ring parts supplied with pistons be recorded
for future reference in the event replacement rings are required.
2. Oil rings are three piece circumferential expander cylinder type. End gap on all rails is .010" to .040". Grind end gaps as necessary. Do not leave
burrs as they will scratch cylinder walls. Do not shorten expander for any reason. Place end gaps as follows: Expander—gap in center of thrust
face 90º to wristpin. Bottom rail—gap 2" to right of expander gap. Top rail—gap 2" to left of expander gap.
3. Compression rings may be cast iron type, chrome faced cast iron type, moly faced cast type and chrome type. The most common combinations
supplied are two chrome faced cast, one chrome faced cast and one cast iron, and one moly faced cast and one cast iron. Chrome faced or
moly faced ring always goes in top groove. Cast iron type usually goes in second groove. Cast iron type is usually a reverse torsion style ring
distinguished by an inside diameter bevel on one side of ring with a “dot”or oversize mark on other side of ring. If two cast iron compression
rings are supplied in set, check to see if one is reverse torsion style ring. Reverse torsion style ring always goes in second groove. The following
rules apply to compression ring identification and placement. Rules are listed in order of priority.
a. Chrome or moly ring goes in top groove.
b. Cast iron regular or reverse torsion goes in second groove.
c. Any identifying “pip” marks, dots or oversize marks go to top of piston.
d. One dot goes in top groove, two dots go in second groove.
e. If both have one dot or two dots, they can go in either groove.
f. If ring has dots and inside diameter bevel, dots go to top of piston.
g. If ring has no dots and inside diameter bevel, bevel goes to top of piston.
h. If ring has no dots, etc. and no bevel, it can go either way.
NOTE: End gap on all compression rings is .012" to .030". In certain instances, the next oversize ringset may be supplied with pistons, ie. + .060" oversize
rings with +.050" pistons. This is permissible but end gaps must be filed. Place end gaps on all compression rings as follows: Second groove—3" to
right of oil expander gap. Top groove—gap 3" to left of oil expander gap.
4. When rings are compressed for piston installation in bore, be sure oil ring expander ends do not overlap and ring stays assembled properly.
Break-In Procedure
This procedure applies to all close fit pistons.
Lugging engine at low rpms and/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.
1. 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
excessive. Do not let engine overheat.
IMPORTANT NOTE: EvOluTION® ENgINES
Proper first time engine start-up and break-in for first 15 minutes is critical to achieve permanent and lasting head gasket seal. Upon initial start-up, idle
engine at 1000–1500 rpm until cylinder head temperature reaches about 250°. Do not crack throttle or put any load on engine during this time. Heat
buildup is necessary to cause heads and cylinders to expand and seal. Do not let heat get excessive. Prior to initial start-up, a .003"-.005" “feeler gauge”
will fit between head gasket and head and cylinder gasket surfaces stopping at fire ring on head gasket. Warming engine as instructed will tightly close
this gap producing a good, lasting seal.
2. 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.
3. 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.
4. For balance of first 1000 miles, speed can be run up to 60–70. Continue to run engine at all different speeds including lower 40–45 mph
ranges. Do not lug engine.
5. 1000–2000 miles basically same as before but a little more liberal with rpm range. Avoid overheating and lugging engine—no drag
racing, trailer towing, etc.
6. 2000 miles and up—have fun!
CAUTION