Iron Stable

Harley-Davidson Fat Boy Builder Components

Genuine HD builder components and aftermarket alternatives that fit the Fat Boy — all years. Select your year for exact fitment and pricing.

Select your year for exact fitment & prices

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Genuine Harley-Davidson (10)

Screamin' Eagle Milwaukee-Eight Headbolt Kit

Genuine Harley-Davidson

Screamin' Eagle Milwaukee-Eight Headbolt Kit

10400069
Iron Pass £291.72£343.20View
Optimize performance from your Stage IV equipped Milwaukee-Eight powertrain by bolting on this Extreme-Flow 64mm Intake Manifold. Cast aluminum body and ported intake runners provide the smooth, undisturbed air intake you need for maximum power output. Delivers a 2% - 4% horsepower increase you'll notice every time you twist the throttle. Updated calibrations make installation and tuning easy. All models require ECM calibration for proper installation. 50-State U.S. EPA compliant.

Genuine Harley-Davidson

Optimize performance from your Stage IV equipped Milwaukee-Eight powertrain by bolting on this Extreme-Flow 64mm Intake Manifold. Cast aluminum body and ported intake runners provide the smooth, undisturbed air intake you need for maximum power output. Delivers a 2% - 4% horsepower increase you'll notice every time you twist the throttle. Updated calibrations make installation and tuning easy. All models require ECM calibration for proper installation. 50-State U.S. EPA compliant.

27300185
Iron Pass £231.74£272.63View
Individual combination front and rear axle wrenches available for your model. 15/16" & 36mm.

Genuine Harley-Davidson

Individual combination front and rear axle wrenches available for your model. 15/16" & 36mm.

94697-08
Iron Pass £21.34£25.10View
Born from racing, the Screamin' Eagle Racing - King 6 is a battle-tested performance transmission developed by the Harley-Davidson Factory Race Team competing in the Mission King of the Baggers series. Engineered for enhanced gear engagement and durability. Key features include modified back-cut angles on the shift dogs to improve gear engagement, and super premium heat treat and shot peening on gears and shafts to ensure race-tough strength and durability. You'll enjoy the smooth shifting performance and know this transmission is built with extreme performance in mind. Bolt-in installation. Super premium heat treated and shot peened gears ensure race-tough strength and durability. Torque capacity increased by +25% over the Original Equipment transmission. Smooth gear engagement for quicker shifts. Back cut gears and shift lug/pockets undercut for improved engagement and reduced friction. Upgraded bearings. Requires Gasket Installation Kit (P/N 36300043), which includes gaskets, O-rings, main drive seal and bearing, and inner primary bearing race (sold separately).

Genuine Harley-Davidson

Born from racing, the Screamin' Eagle Racing - King 6 is a battle-tested performance transmission developed by the Harley-Davidson Factory Race Team competing in the Mission King of the Baggers series. Engineered for enhanced gear engagement and durability. Key features include modified back-cut angles on the shift dogs to improve gear engagement, and super premium heat treat and shot peening on gears and shafts to ensure race-tough strength and durability. You'll enjoy the smooth shifting performance and know this transmission is built with extreme performance in mind. Bolt-in installation. Super premium heat treated and shot peened gears ensure race-tough strength and durability. Torque capacity increased by +25% over the Original Equipment transmission. Smooth gear engagement for quicker shifts. Back cut gears and shift lug/pockets undercut for improved engagement and reduced friction. Upgraded bearings. Requires Gasket Installation Kit (P/N 36300043), which includes gaskets, O-rings, main drive seal and bearing, and inner primary bearing race (sold separately).

36300041
Iron Pass £3069.28£3610.92View
When high-performance engine modifications are made, the increased torque is transferred via the crankshaft to the drive system, putting a significantly higher load on the bearing. The Lefty Bearing is case-hardened on the inner and outer race to provide increased load capacity and enhanced durability in high-torque applications. The bearing is installed in the left side of the crankcase, and supports the output shaft to the primary drive system.

Genuine Harley-Davidson

When high-performance engine modifications are made, the increased torque is transferred via the crankshaft to the drive system, putting a significantly higher load on the bearing. The Lefty Bearing is case-hardened on the inner and outer race to provide increased load capacity and enhanced durability in high-torque applications. The bearing is installed in the left side of the crankcase, and supports the output shaft to the primary drive system.

24004-03B
Iron Pass £53.92£63.44View
Born from racing, the Screamin' Eagle Racing - King 6 is a battle-tested performance transmission developed by the Harley-Davidson Factory Race Team competing in the Mission King of the Baggers series. Engineered for enhanced gear engagement and durability. Key features include modified back-cut angles on the shift dogs to improve gear engagement, and super premium heat treat and shot peening on gears and shafts to ensure race-tough strength and durability. You'll enjoy the smooth shifting performance and know this transmission is built with extreme performance in mind. Bolt-in installation. Super premium heat treated and shot peened gears ensure race-tough strength and durability. Torque capacity increased by +25% over the Original Equipment transmission. Smooth gear engagement for quicker shifts. Back cut gears and shift lug/pockets undercut for improved engagement and reduced friction. Upgraded bearings. Screamin' Eagle branding on bearing door. Requires Gasket Installation Kit (P/N 36300043), which includes gaskets, O-rings, main drive seal and bearing, and inner primary bearing race (sold separately).

Genuine Harley-Davidson

Born from racing, the Screamin' Eagle Racing - King 6 is a battle-tested performance transmission developed by the Harley-Davidson Factory Race Team competing in the Mission King of the Baggers series. Engineered for enhanced gear engagement and durability. Key features include modified back-cut angles on the shift dogs to improve gear engagement, and super premium heat treat and shot peening on gears and shafts to ensure race-tough strength and durability. You'll enjoy the smooth shifting performance and know this transmission is built with extreme performance in mind. Bolt-in installation. Super premium heat treated and shot peened gears ensure race-tough strength and durability. Torque capacity increased by +25% over the Original Equipment transmission. Smooth gear engagement for quicker shifts. Back cut gears and shift lug/pockets undercut for improved engagement and reduced friction. Upgraded bearings. Screamin' Eagle branding on bearing door. Requires Gasket Installation Kit (P/N 36300043), which includes gaskets, O-rings, main drive seal and bearing, and inner primary bearing race (sold separately).

36300037
Iron Pass £3069.28£3610.92View
These premium pushrods are tapered for enhanced clearance at the cylinder head, allowing the use of higher lift cams. The one-piece chrome moly pushrod adds rigidity and durability, and the threaded adjustment feature provides easy cam installation without removing the cylinder heads or rocker boxes. To simplify adjustment, the pushrod features six flats, with one flat marked with a large dot for tracking the adjustment. The threaded rod features 4 flats to reduce wrench swing. Kit includes 4 pushrods, required gloss black pushrod tube covers and o-rings.

Genuine Harley-Davidson

These premium pushrods are tapered for enhanced clearance at the cylinder head, allowing the use of higher lift cams. The one-piece chrome moly pushrod adds rigidity and durability, and the threaded adjustment feature provides easy cam installation without removing the cylinder heads or rocker boxes. To simplify adjustment, the pushrod features six flats, with one flat marked with a large dot for tracking the adjustment. The threaded rod features 4 flats to reduce wrench swing. Kit includes 4 pushrods, required gloss black pushrod tube covers and o-rings.

17900073
Iron Pass £289.68£340.80View
These premium pushrods are tapered for enhanced clearance at the cylinder head, allowing the use of higher lift cams. The one-piece chrome moly tube adds rigidity and durability and the threaded adjustment feature provides easy cam installation without removing the cylinder heads or rocker boxes. Chrome covers. The tube features 6 flats, with one flat marked with a large dot for tracking the adjustment. The threaded rod features 4 flats to reduce wrench swing. Each pushrod features the Screamin' Eagle logo and is marked for "Intake" or "Exhaust". Kit includes 4 pushrods and required pushrod tube covers.

Genuine Harley-Davidson

These premium pushrods are tapered for enhanced clearance at the cylinder head, allowing the use of higher lift cams. The one-piece chrome moly tube adds rigidity and durability and the threaded adjustment feature provides easy cam installation without removing the cylinder heads or rocker boxes. Chrome covers. The tube features 6 flats, with one flat marked with a large dot for tracking the adjustment. The threaded rod features 4 flats to reduce wrench swing. Each pushrod features the Screamin' Eagle logo and is marked for "Intake" or "Exhaust". Kit includes 4 pushrods and required pushrod tube covers.

17900058
Iron Pass £241.39£283.99View
Screamin' Eagle Pro High Volume Oil Pump & Cam Support Plate Kit

Genuine Harley-Davidson

Screamin' Eagle Pro High Volume Oil Pump & Cam Support Plate Kit

62400260
Iron Pass £797.64£938.40View
Screamin' Eagle Milwaukee-Eight 131 Engine. Black finish.

Genuine Harley-Davidson

Screamin' Eagle Milwaukee-Eight 131 Engine. Black finish.

16200342
Iron Pass £6119.94£7199.93View

Aftermarket alternatives

Aftermarket builder components that fit the Fat Boy. Genuine Harley-Davidson is listed above, not here.

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