Inside Harley-Davidson’s All-New Milwaukee-Eight


LET’S GO INSIDE THAT MOTOR…Harley-Davidson’s new Milwaukee Eight is loaded!


The Milwaukee-Eight (M8) motor is the first all-new engine design since 1998 when the then-exciting Twin Cam 88 engine came to life. By all accounts, the M8 is bigger, has newly designed cylinder heads with 4-valves per cylinder and meets the strictest emission standards of the world.

And, as you can see below, the 114ci, 1868cc CVO Street Glide looks absolutely stunning. My gearhead buddies tell me that the 114 puts out a whopping 100.6hp!


2017 CVO Street Glide. 114ci powerhouse bagger. MSRP $37,799 – Source: HDmedia


Oil-cooled or Coolant-cooled heads. You decide.

Best I can tell, you now have the option to getting oil-cooled or coolant-cooled heads. Go 2017 Roadking for oil-cooled or go liquid-cooled with the  “Twin-Cooled” 107ci engine when you demo the Motor Company’s touring motorcycles. — the Road Glide Ultra, Tri Glide Ultra and Ultra Limited models.

The larger 114ci M8 engine comes with liquid-coolant cylinder heads for the CVO Street Glide and CVO Limited models.


Source: HDmedia

Note blue passages in rear cylinder and the black hoses that lead over the heads. That’s where the liquid-coolant or oil-coolant circulates in and on top of the engine heads. Source: HDmedia


Each cylinder now has four valves. (2-intake valves & 2-exhaust valves) for a total of 8 valves. The new motor comes with a higher compression ratio than its predecessor and has more displacement herego, the ability to push out 10% more torque than the Twin Cam.

Note the dual-sparkplugs per cylinder in the rocker box cutout below. Two sparkplugs are better than one from an efficiency of combustion standpoint.


Rocker Box Cutout - HDM8 - Source: HDmedia

Rocker Box – Note the tight-fit rocker arm assembly. HDM8 – Source: HDmedia


Electrical Accessories…bring ’em on!

According to the Motor Company, the electrical charging system produces 50% more charge to the battery. This is a significant improvement given all the gadgets now used on touring bikes such as heated gear, big audio systems and a wide variety of electrical accessories.


0-640x324 HDmedia - BottomEd - BJN37658

The Primary Case is an all new design too. Source: HDmedia


Note the single chain-driven camshaft in the photo below. Single cams provide less chain noise, are lighter and just mechanically simpler than their Twin Cam predecessor. This cam is driven by a hydraulically tensioned chain. I personally prefer the chain-driven cams instead of gear-driven cams. They are much smoother and quieter in my opinion.

And, for the really big news!

Despite the extra power available with the new 107ci motor, it weighs the same as the now-prehistoric Twin Cam 88. There’s no fat in the M8…it’s all muscle. This means more power with less weight (aka: faster acceleration) and better overall fuel economy.


My Bottom Line…

Best I can tell, the new Milwaukee Eight (M8) is technically superior and mechanically better than the Twin Cam it will eventually replace. This said, it’s no high-performance, “Revolution Motor”.

The "Revolution Engine" - Should this of been the "big engine news" for 2017 models? Photo: HDmedia

The Revolution Engine Goes Mainstream at Harley-Davidson. – Should this of been the “big engine news” for 2017 models? Photo: HDmedia

As mentioned in a previous blog post, the new 107ci Milwaukee-Eight produces more torque and kicks out 92.5 horsepower. The 114ci motor is said to generate a whopping 100.6hp.

Yup, the Harley-Davidson Motor Company has a winner here with the Milwaukee-Eight in that it is a slightly more modern version of the Twin Cam and that’s a good thing.

I am somewhat surprised however, that in this day and age of EPA scrutiny and bureaucracy, that the excellent, high-performance EPA-compliant water-cooled engine found in the V-Rods has not yet become more dominant as a feature of Harley-Davidson motorcycles.



Ride Safe Out There.

Motorcycle Marc. #RideSafeOutThere

Motorcycle Marc. #RideSafeOutThere
















About Harley-Davidson Motor Company – Since 1903, the Harley-Davidson Motor Company has fulfilled dreams of personal freedom with cruiser, touring and custom motorcycles, riding experiences and events, and a complete line of Harley-Davidson motorcycle parts, accessories, general merchandise, riding gear and apparel. For more information, visit

About Motorcycle Marc – I’m a motoblogger. I prefer to ride motorcycles but when I can’t ride, I blog about it. Since 2009, I’ve developed a strong, dedicated following of gearheads, motorheads, biker-wannabes and 2-wheeled adventurers who love motorcycles and everything motorcycle-related. #RideSafeOutThere – Marc J. Beaulieu (MJB)

Note: Copyrights and Trademarks are the property of their owners. No infringement ever intended. Manufacturer Names, Logos, Photos/Images, Websites and Model Information are Registered Trademarks of the Manufacturer. Also, note that specifications and any information in this blog is subject to change without notice. No representation of accuracy is made.





  1. Kory J says:

    Best I can tell Mark, the Milwaukee Eight 107 has more power then the Indian Thunder Stroke 111 and its a smaller displacement. Why does no one complain about indian’s power or lack thereof. The technology they use is not much different from HD. I hate it when people think Harleys still break down all the time and are unreliable. That thinking is 30 years old! It is simply not true and those who think different know nothing about harleys. Good article post. Thanks. K

  2. Corburt E. says:

    I’ve been exploring for high quality articles or blog posts for motorcycles. I stumbled upon this site on Yahoo. Studying this info, I found out just what I needed. You have a very nice blog.

    Thank you Corburt…so pleased that you enjoy my adventures on 2-wheels. MJB

  3. Erik C. says:

    I believe your blog site contains some really wonderful information for anyone looking at motorcycling. Thank you for this info on the new Milwaukee Eight motor. I am using it to make by next motorcycle decision. The Harleys are a little over my budget I must say but this looks like one heck of a motor. Thanks.

    Hi Erik…have a read of my latest blog post to get additional perspective on how this motor runs. It’s amazing!…”Roadtest: Street Glide Special with Milwaukee Eight Motor. – Thanks for reading my blog. — Motorcycle Marc

  4. Maurice D. says:

    Thank you for this sensible critique. Me and my neighbor were just preparing to do some research on this. We happen upon your blog on Google. I learned more from this post than anywhere else. I’m very glad to see such magnificent info being shared freely out there. Keep up the good work Motorcycle Marc.

    Thank you Maurice. I blog it as I see it. Thank you for reading my blog. MJB

  5. Burt O. says:

    Love your blog. Some really prized blog posts on your site, saved to bookmarks. Award winner. Good work here. Thanks.

    Thank you Burt…—Motorcycle Marc

  6. Alisa B says:

    I was just looking at your Inside Harley-Davidson’s All-New Milwaukee-Eight. I just want to tell you, In case you didn’t already know…exellent article! Thanks.

  7. Darrel L. says:

    This blog site is really interesting and this is an excellent article on the new Harley motor. I have bookmarked it. Do you allow guest posts on your site?
    Let me know please.

    Hello Darrel…thank you for reading my blog. I have yet to allow guest posts but I am looking into it and reviewing a number of articles for this purpose. Topics need to be motorcycle-related in some way. Feel free to send me a draft for review if you wish. Go to my contact me page for my email. — MJB

  8. Corban G. says:

    Good write up. Truly liked reading it. When will you do your roadtest?

    Thank you Corban…Hoping to do a full roadtest by year end 2016. – MJB

  9. Orvall S. says:

    Great article. Adding to my favorites. Its easy to read and understand. Love your blog.

  10. Tom M. says:

    Love my Harley’s. Does this new M-8 come with a neutral gear that you can readily find? Now THAT would be real progress.

    Time will tell Tom…:) I will comment on it later this year when I put one of the M8s through a complete MJB roadtest…Thank you for reading my blog. MJB

  11. Kristen A. says:

    I absolutely love your blog.. Very nice colors
    & theme. Did you develop this amazing site yourself?
    Please reply back as I’m trying to create my own personal
    website and want to learn where you got this from or what the theme is called.Great article on the new Harley engine too.

    Hello Kristen,
    Glad you like my blog…Thank you. Yes, I did develop it myself using WordPress from the company. I use html code as needed to post images and various widgets. Highly recommend the WordPress platform for blog design and even website design. All the best. Ride Safe Out There…MJB

  12. Reid M. says:

    The new motor has claimed 82 HP on the Harley Davidson web site..still not as much as some other bikes that are sold in that class.
    Hello Reid…Thank you for your feedback/observation.

    82hp on a 107ci and 1750cc motor is too low. A basic rule of thumb I use is that 1hp = 16cc. So 82hp x 16 = 1312cc. So, 1,750cc divided by 16cc = 109hp…remove from this figure a factor for drag/friction etc to the rear wheel, estimate 15% or so, and you get closer to the 92.5hp.

    Best I’ve been able to figure over the years is that different dyno manufacturers with different software give different readings on horsepower…At the Motor Company’s stated 111.4 ft-lb for the 107ci, 1750cc engine model, my rough, estimated gearhead math estimates the Milwaukee-Eight to be putting out closer to 92.5 hp delivered to the rear wheel. Ride Safe Out There. MJB

  13. Greg N. says:

    This is a really interesting blog. Love the new Harley motor.
    You are a very skilled blogger. I have joined your feed and look forward to seeking more of your great posts.
    Also, I’ve shared your site in my social networks! Thank you.

    Thank you Greg for reading my blog. Glad you liked this M8 article. Ride Safe Out There. MJB

  14. Frank T says:

    One thing missing in this article is that the Motor Company said the M8 is “backwards compatible” with the Twin Cam Frame. So, you could throw in this new engine into your 2010 Street Glide if you wanted to for example.

    I find the “hidden sparkplug” set up is stupid and there’s no reason for it. Looks like you have to remove the gas tank just to do a simple plug change.
    Good points here Frank…thank you for reading my blog. Not sure what the powerplant engineers at Harley-Davidson were thinking about the plug positioning. I agree it doesn’t make sense. As for the “backwards compatible”…not impressed…not a real benefit to customers per se. Ride Safe Out There. MJB

  15. Charmaine says:

    Very interesting reading. Have they appointed a nickname for this new motor? Great blog. Charmaine

  16. Jim F. says:

    That top engine view makes the engine kinda look like a hybrid between the Knucklehead and Shovelhead engine. the Knuckleshovel! Great article. Thanks!

    Hi Jim…interesting observation you make here.

    The knucklehead name refers to the distinct shape of the rocker boxes on those early 1930s-40s Harley-Davidson engines. That motor was a 45-degree, pushrod actuated overhead valve V-twin engine with two valves per cylinder. According to biker lore, the Knucklehead nickname arose from the California chopper culture of the late 1960s.

    The Shovelhead name was an offshoot of the Harley-Davidson Knucklehead engine but with a different look to it. According to biker lore, the name was derived from the appearance of the rocker box covers which resemble the head of shovels when they are inverted. The shovel engines powered Harleys from 1966 up until the introduction of the Evolution engine in 1984. The Shovelhead design produced 10% more horsepower than the Panhead engine which it replaced.

    It will be interesting to see what Harley enthusiasts will come up with for a name beyond the branded “Milwaukee-Eight” chosen by the Marketing Pros as the Motor Company. For example,

    “ValveHead” for the total of 8 valves.
    “CoolHead” for the engine’s liquid coolants…or take on the term “TwinCooled” as HD calls them.
    “M8” – I’m hearing and seeing the M8 term used by my gearhead friends.
    “PowerHead”…114ci pushes out 110.6 hp.

    We’ll have fun with this one I reckon Jim. Thank you for reading my blog. MJB