S&S Cycle Bore Big Twin Stroker Kit 1936–1999 3 7/16 - 3 1/2 User Manual

Page 5

Inadequate clearance between rods or too much clearancing on rods will cause unwarranted stress on connecting rods, rod bearings,
pistons, etc. resulting in possible failure of one or all aforementioned parts.

C. Thoroughly clean all parts to remove dirt, filings, etc.

Burrs, dirt, filings, etc. left on connecting rod components may circulate in oil damaging other parts possibly causing engine failure.

3. Lower End Assembly (All)

NOTEs:
•

S&S big twin flywheels with serial numbers that start with a letter or those numbered 1382 or higher are made from closed die, heat treated, steel
forgings. They do not have connecting rod thrust washers like earlier S&S flywheels, because present flywheel material is harder than thrust washers
previously used.

•

S&S flywheels come with either one or three timing marks. A single timing mark represents front cylinder. On flywheels with three timing marks, an “F”
stamped by a mark means front cylinder, an “R” means rear cylinder and a “TF” means top dead center front cylinder. In both cases, when front or rear
mark is placed in center of timing hole it means that that cylinder is timed at 35° before top dead center. We recommend that big inch engines be timed
at 35° initially. See Step 5, “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.

•

Assembling flywheels, mainshafts and connecting rods can be easy or difficult. Degree of difficulty is determined by builder technique and parts at
his disposal. While S&S flywheels have been noted for their easy truing qualities, they can be difficult to true if a defective part is used that should have
been detected before 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. Use cleaning agents that do not leave harmful residues, and 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.

•

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 using compressed air are harmful to eyes and body. Use protective eye wear and always
direct air stream away from yourself and others.

Perform following steps when assembling flywheels:
A. Thoroughly clean all parts to be used. This includes mainshafts, main bearings, connecting rods, rod bearings, crankpin nut retainers and

screws if they are to be used, keys and flywheels including tapers and keyways.

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

B. Check both mainshafts between centers for taper surface to bearing surface concentricity. Make sure centers on shafts are clean

beforehand. If tapers and bearing surfaces are concentric with each other and with center, then truing will be easier. See Picture 2, next
page.

NOTE: Current stock specs. allow maximum of .001" runout between taper and bearing surfaces. We feel this is too much and prefer to see .0003" or less
with an absolute maximum of .0005". S&S shafts are .0003" or less.

CAUTION

WARNING

CAUTION