S&S Cycle Sidewinder 3 5⁄8 Big Bore Cylinders for Harley-Davidson Sportster Models—1986–2003 User Manual

Page 7

8. Lower End Assembly (All)

NOTES:

• All current production S&S® Evolution® Sportster® model flywheels are made from closed die, heat treated, steel forgings. They do not have

connecting rod thrust washers like earlier S&S or stock flywheels, because present flywheel material is harder than thrust washers previously used.

• S&S Sportster® model style flywheels come with three timing marks, “F”, “R” and “TF”. The “F” mark stands for front cylinder 30° before top dead

center (TDC). The “R” mark is rear cylinder 30° before TDC, The “TF” mark is TDC front cylinder. When “F” or “R” mark is placed in center of timing
hole it means that cylinder is timed at 30° before TDC. We recommend that big inch Sportster® engines be timed at 30–32° before TDC rather than
the stock 40° before TDC. See Performance Notes, 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.

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 fashion.

• Many problems in assembling and truing flywheels can be prevented by careful inspection of all parts used in the assembly.

• Cleaning parts prior to and during assembly and keeping parts clean after final assembly are imperative to minimize contaminants that may

circulate in oil and shorten engine life. Many parts can be cleaned with soap and water first. Then, reclean all internal parts and gasket mating
surfaces using high quality solvent that does not leave any harmful residues. 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. During actual final assembly, recoat all internal
parts with high quality engine oil or assembly lube such as S&S 51-9000.

Manufacturing chips, dirt and/or other contaminants circulating in engine oil may possibly damage engine components resulting in
shorter engine life and possible 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. Never direct compressed air toward other
people.

Perform following steps when assembling flywheels:

A. Thoroughly clean all parts to be used. This includes mainshafts, main bearings, connecting rods, rod bearings, keys and flywheels

including tapers and key ways.

Burrs, dirt, filings, etc. left on flywheel assembly parts may circulate in oil damaging other parts possibly causing engine failure.

B. Inspect key ways and oil holes in flywheels for burrs and remove if necessary.

NOTE: S&S does not recommend lapping tapers to remove burrs. This practice tends to distort the taper by removing material unevenly around the

circumference. This makes flywheels difficult if not impossible to true. In addition the lapping process work hardens the surface of the taper. This
hard surface makes it very difficult to pull shaft or crankpin into taper. If crankpin and shafts are not pulled fully into flywheel tapers, excessive rod
side play and assembly width may result. Lapped flywheel tapers are also very difficult to resurface if repairs are ever needed.

S&S warranty is void if flywheel tapers are lapped.

C. Check keys in grooves of shafts. Key should be light hand press fit in groove. If key is too tight in groove, sand side key with fine sand

paper on a metal plate or other flat surface. Do not hammer key into groove.

Hammering tight key into groove may result in irreparable damage to shaft.

CAUTION

WARNING