The Milwaukee-Eight keeps the familiar 45-degree Harley-Davidson Big Twin layout, but pairs it with four valves per cylinder and counter-balancing. That combination—traditional V-Twin identity alongside a substantially revised engine design—is the family’s defining appeal. The details are not identical across every Harley: displacement, cooling and output depend on the motorcycle and model year.
What does “Milwaukee-Eight” mean?
Harley-Davidson introduced the Milwaukee-Eight for 2017 models. One camshaft operates four valves in each cylinder—two intake and two exhaust—for eight valves total across the V-Twin. The name refers to that valve count.
The engine retains the 45-degree V-Twin configuration associated with Harley-Davidson’s Big Twin engines. Harley-Davidson describes the family as counter-balanced to reduce vibration while maintaining the traditional V-Twin look, sound and feel. Those are the manufacturer’s design aims, not a guarantee of a particular riding impression for every model or rider. Harley-Davidson’s engine history traces the family from its 2017 debut through later versions.
What changed from the earlier engine design?
Four valves per cylinder
The four-valve heads are a concrete departure from the previous model-year heads discussed at launch. Harley-Davidson said they offered 50% more intake and exhaust flow capacity and claimed 10% more torque. Both were manufacturer comparisons between 2017 Touring models and 2016 Touring models—not universal figures for every Milwaukee-Eight or later model year. The 2016 launch announcement gives that comparison’s scope.
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Counter-balancing
Harley-Davidson says all Milwaukee-Eight versions are counter-balanced to reduce vibration. This design choice complements rather than replaces the recognizable V-Twin layout: the goal is to retain the engine’s traditional character while addressing vibration through internal engineering.
A growing family
The first versions were 107 and 114 cubic inches. Harley-Davidson’s engine history records the later addition of a 121-cubic-inch regular-production version and variable valve timing in 2023. These are family milestones, not a single specification shared by every motorcycle bearing the name.
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- Black Oil Filter variant of the Bel-Ray Synthetic 3-Hole Complete Oil Change Kit that fits Harley-Davidson Milwaukee-Eight (2017-Up), sized to the M8's larger 5-liter sump with full-synthetic engine oil and separate trans and primary fluids
- Fits 2017-Up M8 Touring and 2018-Up M8 Softail chassis across all current Milwaukee-Eight displacements - 107, 114, and 117 cubic inches
- Includes 5 liters of Bel-Ray V-Twin Synthetic Engine Oil 20W-50 (PAO and synthetic ester base, API SN, JASO MA2), 1 liter of Bel-Ray Big Twin Transmission Oil 85W-140 (API GL-5), and 1 liter of Bel-Ray V-Twin Primary Chaincase Lubricant
- Wet-fill service is covered by the 1-liter primary bottle; a dry-fill primary needs roughly one additional quart of primary chaincase lubricant beyond what is supplied
- Assembled by Twisted Choppers using Bel-Ray V-Twin Synthetic Engine Oil and a HiFloFiltro HF171BRC racing-style black filter, sealed with three drain-plug O-rings sized for the M8 engine, transmission, and primary plugs
How do Milwaukee-Eight versions differ?
Displacement alone does not tell the whole story. Harley-Davidson has offered air-cooled and oil-cooled versions, Twin-Cooled configurations with liquid-cooled cylinder heads and fairing-mounted radiators, and a center-cooled 117 configuration with liquid-cooled heads and a frame-mounted radiator. Later specifications also include a 121-cubic-inch VVT version. Which engine is installed depends on the model, market and model year.
Harley-Davidson’s 2025 owner-manual examples show why configuration matters. A listed Milwaukee-Eight 117 is 117 in³ (1,923 cm³), with a 4.075 in (103.5 mm) bore and a 4.500 in (114.3 mm) stroke. The manuals describe 117 and 117 H.O. configurations with oil-cooled cylinder heads and an oil cooler, while the separate center-cooled 117 documentation specifies liquid-cooled heads, a frame-mounted radiator and an oil-cooled crankcase. These descriptions apply to the configurations covered by those manuals; consult the manual matching the exact motorcycle for its specifications and service details. Harley-Davidson’s Service Information Portal provides model-specific documentation.
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- Klotz Synthetic Motor Oil is designed specifically for the unique performance requirements of Harley-Davidson V-Twin hardware to provide outstanding oxidation performance and detergency for smoother, quieter engine, clutch, and transmission operation. Our change kits prevent wear and corrosion for both the engine and gear hardware with just the right amount of lubricant – no more, no less.
- Our top-tier additive package utilizes high-quality base oils and advanced polymers to maintain shear stability and optimize both the power and efficiency of your motorcycle engine and transmission by harnessing friction-modifying chemistry to reduce operating temperature. Detergents and dispersants in the oil keep the engine clean and mitigate deposit formation to keep your vehicle running like new.
- Klotz KH-108 Motor Oil Change Kit includes 5 quarts of Multi-Viscosity Synthetic Engine Lubricant 20W-50, 1.5 quarts of Primary Chain Case Lubricant, 1 quart of Transmission Gear Lube, 1 Hiflofiltro Filter (HF-171CRC), and 3 Cometic Drain Plug O-Rings – everything you need to get your wheels back on the road.
- For servicing Twin Cam 1999-2018 and Milwaukee-Eight 2017-2022 V-Twin engines.
- We believe your motorcycle deserves the best products available. Klotz is committed to using the most advanced technology available and never compromising on quality for profit: no cost-optimizing or substitution of lesser ingredients. Klotz Synthetic Motor Oil Change Kit meets and exceeds warranty requirements for compliance and protection.
A model-specific 114 example
Harley-Davidson lists the 2025 Freewheeler with a Milwaukee-Eight 114 (114 cu in), rated at 119 ft-lb of engine torque at 2,750 rpm and 90 hp at 4,750 rpm. Those figures are for that listed model and its published specification; they should not be treated as ratings for every motorcycle equipped with a 114. See the 2025 Freewheeler specifications.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to identify the right engine and parts for your Harley
- Identify the motorcycle and model year. Start with the exact model, year and market, rather than relying on “Milwaukee-Eight” or a displacement number alone.
- Check the matching owner’s manual. Confirm displacement, cooling configuration, fluid requirements and service capacities in the documentation for that motorcycle.
- Verify parts against exact fitment. For an oil filter, fluids, tools or performance parts, check the manufacturer’s fitment information for the specific model and year. The engine family name by itself does not establish compatibility.
Cooling systems and service details differ among Milwaukee-Eight configurations, so a capacity or part that applies to one motorcycle may not apply to another. Harley-Davidson’s engine history and manuals establish the range of designs; use the exact vehicle documentation and parts listing for a purchase or service decision.
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- Fitment：The big head side is for 2007-2016 Twin Cam Models, 2017-UP MILWAUKEE 8(M8) Engine Models, 2006 Dyna; The small head side is for 1999-2005 Dyna, 2000-2006 Softail, 1999-2006 Touring models (Note: Do not include 1999 Softail)
- Function: The tool is designed to lock the camshaft and crankshaft gears which allows for removal or replacement of the camshaft and crankshaft bolts
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- Formulated specifically for V-Twin engines
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- Excellent clutch feel and clutch protection
- Shear stable, ester-fortified formula maintains oil viscosity and film thickness
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