S&S Cycle T143 Twin Cam Engine for 1999-2017 Harley-Davidson Dyna and Touring

S&S Cycle T143 Twin Cam Engine for 1999-2017 Harley-Davidson Dyna and Touring

The S&S T143 is the largest displacement engine S&S builds that fits in a stock Harley-Davidson Twin Cam chassis — and it is not a subtle upgrade. Riders who have lived with this engine describe a machine transformed: throttle response that demands full attention, acceleration that reframes every on-ramp, and a presence on the road that makes everything else feel ordinary.

Key Features

• Not compatible with Harley-Davidson Softail models or Twin-Cooled models — fits Dyna and Touring platforms only; see fitment table for full details
• 143-cubic-inch displacement — the largest S&S Twin Cam engine engineered to fit a stock HD chassis without frame cutting or modification
• S&S B3 Special Application CNC-machined cylinder heads with 2-bolt exhaust flanges — requires a special intake manifold, throttle body, or carburetor not included with this engine
• S&S 635 Easy Start gear drive cams for strong output with manageable starting behavior
• S&S 1.725:1 ratio rocker arms producing .674″ total valve lift
• S&S premium high-performance tappets
• 3-piece flywheel assembly
• Electronic compression releases
• S&S high-flow oil pump and cam cover
• Gloss black rocker covers, gear cover, tappet blocks, and pushrod tubes
• Available in Black, Black Edition, and Stone Gray finishes (Silver and Stone Gray availability varies by model group — see notes)
• Made in the USA
• 1-year limited warranty — engine noise and damage from abuse are not covered

Technical Specifications

• Displacement: 143 cubic inches
• Compression Ratio: 10.47:1
• Camshaft: S&S 635 Easy Start gear drive
• Cam Drive: Gear drive
• Rocker Arms: S&S 1.725:1 ratio forged
• Total Valve Lift: .674″
• Tappets: S&S premium high-performance
• Flywheels: 3-piece
• Cylinder Heads: S&S B3 Special Application, CNC machined, 2-bolt exhaust flanges
• Oil Pump: S&S high-flow
• Compression Releases: Electronic
• Intake / Throttle Body / Air Cleaner: Not included — special S&S performance intake required; stock components not compatible
• Finish Options: Black, Black Edition, Stone Gray (Silver status pending — see Block 1 notes)
• Dimensions — active variations (L x W x H): 26.5″ x 24.56″ x 20.06″
• Emissions: Not legal for sale or use in California on pollution-controlled motor vehicles. Not legal for sale or use on any EPA pollution-controlled motor vehicle.
• Origin: Made in USA
• Warranty: 1-year limited; engine noise and abuse damage excluded

Fitment Notes

• Not compatible with any Harley-Davidson Softail model — absolute exclusion regardless of year
• Not compatible with Twin-Cooled Touring models (select 2014-2016 models)
• Three fitment groups apply — select the correct variation for your year and platform: 1999-2006 non-Softail Twin Cam (except 2006 Dyna); 2006-2017 Dyna; 2007-2016 Touring
• Special intake required: S&S B3 heads are not compatible with stock intake manifolds or throttle bodies. S&S offers a dedicated 70mm throttle body and air cleaner kit for EFI applications, and carb kits for carbureted builds — neither is included with this engine and must be ordered separately
• This is an ultra-performance and race application engine. Professional installation and tuning expertise are required. Longevity, engine noise, vibration, and throttle sensitivity have been intentionally compromised in exchange for maximum performance. It is the purchaser’s responsibility to assess suitability for their application
• Review the Fitment tab for a complete year and model breakdown