1986-2012 Sportster® & Buell - S&S Cycle

S e ction 4: 1986-2012 Sportster® & Buell ®S&S ®Parts forTwin Cam 96 /103 2007-2012Parts forTwin Cam 88 ®1999-2006Parts forEvolution ®1984-1999Parts forSportster ® & Buell ®1986-2012Parts forVintage Engines1926-1984Parts forX-Wedge®2007-2012PERFORMANCEKITSSidewinder ® Big Bore KitsWhen the Harley-Davidson® Evolution® powered Sportster® was released in 1986 it wasobvious that the new engine had a lot of potential. Aside from the obvious benefit ofaluminum finned cylinders and a modern cylinder head and valve train, the crankcases werebeefed up enough to handle larger bore sizes with far fewer problems than previous engines.The crankcase cylinder deck height was raised to be the same as a big twin engine at 5.375"from the center of the crankshaft, and the cases were stronger in general so that materialdid not have to be welded on to the sides of the cylinder deck in order to accommodate 35/8"bore cylinders. The taller crankcase deck did result in cylinders that were too short to allow apractical stock bore stroker to be designed, so big bore was the only option!FITMENT• 1986-'03 Harley-Davidson® Sportster®• 1994-'02 Harley-Davidson® Buell®FEATURES AND BENEFITS• Available in three displacements, for four-speed (1986-’90) and five-speed (1991-’03)models, and in natural aluminum and black powdercoat finish.• Two displacements available : 79" and 89" big bore stroker kit• Requires that the crankcase cylinder spigot holes be bored to accept the larger cylinders• Complete instructions are provided for this machining operation, and S&S has specialtools available that simplify the crankcase boring procedure. See Section 9 in thiscatalog for more informationThis is a basic Sidewinder® Kit . The engine builder has chosen flattopped pistons to be used with the stock cylinder heads. In addition he/she has selected standard adjustable pushrods and a manifold to beused with an existing S&S carburetor.Parts forVictory®, Off-road& MetricRacingProductsTools & ShopSuppliesDealer Services& Promo ItemsWarranty &Company PolicyOEM Cross ReferenceAppendix & IndexS&S® SIDEWINDER® BIG BORE KITS for 1986-'03 Harley-Davidson® SPORTSTER® modelsDisplacement Stroke BoreCompressionRatioPiston Type Cylinder Length Engine Life Application Part No.79" Sportster** 313⁄16" 35⁄8" ‡ Forged Stock Stock-like 1986 to 2003 91-300289" Sportster* 45⁄16" 35⁄8" ‡ ForgedCTO+.437"1986 to 1990 91-3121Very good(5.087") 1991 to 2003 91-3123Specify Specify Specify Specify 1986-2003 106-5834All other Sportster & Buell® year groups must use the CTO part number.‡ Compression ratio depends on cylinder head type used.If stock heads are used extensive cylinder head modifications must be performed, making compression ratios completely dependent on final combustion chamber volume.† 1991 and later engines require conversion to 1986-’90 style pushrod tube assemblies when using adjustable pushrods. S&S kits for 1991 and later engines include a special pushrod tube adapter.Pushrod tube assemblies are not included and must be purchased separately.** This kit has stock height cylinders and will fit Buell® motorcycles. * Denotes kit supplied in S&S Hot Set Up Kit.Parts Included in S&S® SIDEWINDER® BIG BORE KITS for 1986-'03 Harley-Davidson® SPORTSTER® modelsKit Part FlywheelGaskets HeadHead MountDisplacement StrokePistons CylindersPushrods Pushrod ManifoldNo. AssemblyHead BaseBolt Center Front79" 313⁄16" 91-3002 Forged l l l91-3121 l Forged l l l l l l l l l89" * 45⁄16"91-3123 l Forged l l l l l l l l l* Denotes kit supplied in S&S Hot Set Up Kit.4-14Order toll free 866-244-2673