Harley-Davidson Milwaukee-Eight Engine Guide: 107, 114, 117, and 121 Rated
- jamesjordan
- Aug 7
- 5 min read
Quick answer: The Milwaukee-Eight is Harley-Davidson's current Big Twin, in production since the 2017 model year in 107, 114, 117, and 121 cubic inch versions. It is the smoothest and most reliable Big Twin Harley has built, and early oil pump problems were sorted by 2020. MGR Reliability Rating: 8.5/10.
Spec | Milwaukee-Eight |
Production years | 2017 model year to present |
Displacements | 107 (1,746cc), 114 (1,868cc), 117 (1,923cc), 121 (1,977cc) |
45 degree OHV V-twin, single cam, 4 valves per cylinder, dual spark plugs | |
Cooling | Precision oil cooled; Twin-Cooled liquid cooled heads on select Touring and CVO models |
Used in | Touring, Softail, Trike, and CVO families |
MGR Reliability Rating | 8.5/10 |
What the Milwaukee-Eight is and why it exists
The Milwaukee-Eight replaced the Twin Cam in the 2017 touring lineup and moved into the redesigned Softail family for 2018. The name refers to the eight total valves, four per cylinder, which was a first for a Harley Big Twin. It kept the classic 45 degree architecture and pushrod layout but added a single chain-driven cam, dual spark plugs per cylinder, and an internal counterbalancer that cut primary vibration dramatically while leaving enough character at idle to still feel like a Harley.
It launched as the 107 (1,746cc) with the 114 (1,868cc) optional on heavier models. The 117 (1,923cc) was the CVO engine before becoming standard equipment on performance models like the Low Rider ST and, from 2024, on the Street Glide and Road Glide. The 121 (1,977cc) arrived on the 2023 CVO Street Glide and Road Glide.
VVT arrives for 2026
For 2026, variable valve timing reached regular production models for the first time. The Street Glide Limited and Road Glide Limited carry the Milwaukee-Eight VVT 117, rated by Harley at 106 hp and 131 lb-ft of torque. The CVO Street Glide Limited runs a VVT 121 rated at 115 hp and 138 lb-ft, while the CVO ST models keep a non-VVT 121 High Output rated at 127 hp and 145 lb-ft. VVT widens the powerband and helps heat management without changing the pushrod character of the engine.
Reliability, known issues, and the years to be careful with
The Milwaukee-Eight has been a clear reliability step forward, but the first years were not perfect. Documented issues worth knowing:
Oil sumping on early engines. Some 2017 and early 2018 engines could let oil accumulate in the crankcase, showing up as blue smoke on cold start, oil residue in the air filter, or power loss on long high rpm runs. The oil pump and pressure relief design was revised during 2018 and finalized by roughly 2020. This was widely discussed on owner forums and covered in the service literature, though Harley never issued a blanket recall for it.
NHTSA recall 17V-333: oil cooler line clamps on certain 2017 touring models could detach.
NHTSA recall 18V-734: clutch master cylinder on certain 2017 to 2018 models could lose the ability to disengage the clutch.
Lifter and cam chest noise complaints appear on owner forums for some early engines. Noisy does not always mean failing, but a knocking top end on a test ride deserves investigation.
From 2020 onward the platform is mature, and there are no engine-wide recalls on 2020 and later Milwaukee-Eights as of this writing. On a 2017 or 2018 bike, run the VIN at a dealer and confirm both recalls were completed, then check the air filter for oil residue and watch for smoke on a cold start.
Realistic lifespan
We will not invent a mileage number, and no honest source can promise one. What the real world shows: the touring community regularly puts six figure mileage on these engines with documented oil changes, and the bottom end has proven stout. The four valve heads also run cooler than the Twin Cam they replaced, which helps long term durability. A neglected engine of any make will not get there. Service history matters more than the odometer.
Maintenance and oil notes
General guidance, not a substitute for the service manual: Harley specifies 5,000 mile service intervals, with 20W-50 oil such as Screamin Eagle SYN3 or an equivalent quality synthetic commonly used. Three separate fluid compartments (engine, primary, transmission) each need attention. Twin-Cooled models add coolant service. The hydraulic lifters need no adjustment, which is part of why the engine is so undemanding to live with.
Models that use the Milwaukee-Eight, with our ratings
We have rated most of the current Milwaukee-Eight lineup separately:
FAQ
How long does a Milwaukee-Eight engine last?
With documented maintenance, high mileage examples well past 100,000 miles are common in the touring community. There is no engineering reason a cared-for Milwaukee-Eight cannot reach that territory, but service history is the real predictor, not the model year.
Which Milwaukee-Eight years should I avoid?
Be careful with 2017 and early 2018. Those years carry the early oil pump design linked to sumping complaints plus two recalls. Verify recall completion and check for cold start smoke. From 2020 on, the platform is mature and we would buy any year with records.
Is the Milwaukee-Eight reliable?
Yes, by Big Twin standards it is the most reliable engine Harley has made. We rate it 8.5/10, docking points only for the rough first two model years and the price of dealer service.
What is the difference between the 107, 114, 117, and 121?
Displacement and tune. The 107 (1,746cc) was the base touring engine, the 114 (1,868cc) serves most Softails, the 117 (1,923cc) is now the standard touring and performance engine, and the 121 (1,977cc) is the CVO engine, available with VVT from 2026 on the CVO Street Glide Limited.
Does the Milwaukee-Eight have VVT?
From the 2026 model year, yes on select models. The Street Glide Limited and Road Glide Limited use the VVT 117, and the CVO Street Glide Limited uses the VVT 121. Standard 117 and the 121 High Output remain fixed timing.
What oil does a Milwaukee-Eight take?
Harley specifies 20W-50, with SYN3 as the factory fill. Any quality 20W-50 motorcycle oil meeting the spec in your owner manual is fine. Change it on the 5,000 mile schedule and the engine will not complain.
Sources
Last updated: August 6, 2026. MotoGearRater is independent. We do not sell motorcycles and nobody pays for a rating.
