Man O-War Motor Products

10629 Hwy 42

Newton, WI 53063


The TRUE Solution to a 

Smooth Lower End

Darkhorse Crankworks' proprietary process to blueprint and balance, build or remanufacture crankshaft assemblies for the best builders in the world is the key to your dealerships success.  We have over 40 years of experience remanufacturing Harley-Davidson® engines and are considered the motorcycle industry's leading experts. Our proprietary bearing and engine case upgrades came from our passion to provide outstanding service to our Harley-Davidson dealers and performance shops throughout the world!

On The Cutting Edge

Darkhorse Crankworks was responsible for building and engineering the crankshaft work in the below videos for Harley-Davidson & Pepper: DLRA Speed Week held in Austraila and prototype Project 156 for Victory Motorcycles. View videos!

Family Owned and Operated

Our family owned business started in 1980 with a passion to only build the best Harley-Davidson® motors, with that amount experience building engines and multiple National Championships (James Gang/Hoban Brothers Racing) in professional motorcycle racing, you can rest assured you are getting the best precision work available in the industry today.

Please contact us before you buy a new Harley-Davidson® crankshaft assembly, as we can blueprint and remanufacture Harley-Davidson® crankshafts, very often for half of the cost of new.  If the OEM crankshaft cannot be remanufactured, or you choose to increase the displacement, we can supply you with our Signature Series Man O-War crankshaft and/or assembled lower unit that will be the rock solid foundation 

to your bottom line!

Our Products Stand the Test of Time and Torque 

Darkhorse Crankworks continues to be the leaders in the motorcycle industry developing reliable power and a smooth delivery from our precision parts, high performance crankshafts, our Man O-War®  motorproducts  and engine crankcase upgrades.  Whether it’s building a new 4" - 4 3/8" - 4 5/8” stroker crankshaft, upgrading cases and bearings to support today’s modern high-output crankshafts, to rebuilding a vintage Knucklehead lower end; you have a foundation you know will stand the test of time and torque.

Complete the online forms for the Remanufacture Work Order or the Flywheel Order Online Form. All work must be accompanied with a completed work order form to ensure your work is done completely, properly and in a timely manner.

Pioneers of our Pro-Plug & Shifting Flywheels

Fielding questions about run-out and scissoring/shifting 1st things 1st, we are not aware of 1 of our flywheels that have shifted on the crankpin, truthfully, NOT 1!  We have remanufactured well over 10,000 TwinCam crankshafts - That is our sole testament to the value of our engineered Pro-Plug system.  It provides integrity to the crankshaft as a whole to resist spreading of the wheels 180 degrees from TDC and does NOT allow the wheels to shift, something welding alone or ANY 5 piece crankshaft can not provide.

View warranty info. All street version crankshafts and parts come with a 24-month, unlimited mileage warranty against manufacturer defect. Our craftsmanship is unparalleled in the motorcycle industry.



Man O War Motor Products


Engineered Rock Solid Foundation

Darkhorse Crankworks, long regarded as producing the strongest foundations for all Harley-Davidson® performance engines, released our Man O'War® crankshaft that allows you to put even more HP to the road without concerns associate with OEM crankshafts in performance motor builds



Crankcase - Service & Assembly

Darkhorse Crankworks is the "go to" facility for the high performance engine builders and Harley-Davidson dealer network in crankcase upgrades and repair.  Our primary goal is to engineer crankcase upgrades to combat the motor company cost reduction directives.  Shortly after the double flat-roller bearing motors were released in 2003, we engineered the system that would support the ever growing displacement and horsepower outputs from the new engine design.  Our unique Milwaukee 8®  & TwinCam® Timken bearing upgrade system is a cut above the competitions with our procedure to retain the right side bearing along with verifying main bearing bore alignment of < .001” in 1 placement in our CNC mills.

View Retail Price List




Man O-War Crankshafts

We are committed to building the strongest foundation for top engine builders and dealers across North America and around the world.

How It All Began

Our distributors and dealers ask us to build Darkhorse certified crankshaft assemblies. These crankshaft assemblies needed to meet our stringent tolerances and be balanced to our specifications. To fulfill this request, we formed alliances with top flywheel manufacturers across the USA who now supply us with components which we couple with our precision parts to create our Man O-War crankshafts. The end result is an affordable, top-of-the line crankshaft. We manufacture crankshafts that are truly unique. They are designed and built specifically for an intended application and customer. This value added service, provides you with a bottom end that will surely strengthen your bottom line. This is a product that will stand the test of time and torque.  

Contact Us

Darkhorse Crankworks

10629 Wisconsin Highway 42, Newton, Wisconsin 53063, United States (920) 726-9999


Open today

09:00 am – 05:00 pm