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.

Man O' War Motor Products

How It All Began

Our distributors and dealers asked us to build new Darkhorse certified crankshaft assemblies. The crankshaft assemblies needed to meet our stringent tolerances and be balanced to our specifications. To fulfill this request, we formed alliances with top manufacturers across the USA who supply us with components which we couple with our own precision parts. 

The end result is an affordable, Premium component, custom built 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. 

Our Inventory

We have certain crankshaft configurations already in inventory that have been balanced to a specific piston weight and configuration

 or if an “off the shelf” crankshaft is what your build or budget requires, we also stock 

OEM Harley-Davidson®, Screamin Eagle® & S&S® crankshafts.

Ordering is Easy

New Crankshafts can be ordered by filling out the New Orders Form or purchasing a Man O-War assembly (limited configurations) that have been balanced to a specific piston weight right off this website or by contacting  Andrew in our Technical sales team at 920.726.9999

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Custom Engineered & Handcrafted crankshafts made in the USA 

Our exclusive line of parts, supports the ever-growing need for big horsepower and torque. 

Chose Our Competition H-Beam Chromoly connecting rod that is second to none or any of our other product options from our very own Competition ConnRods, S&S, JIMS USA & CARRILLO connecting rods.  Centerlines are all machined to within .0003” of each other. They are the only rod that can provide you a true .001” stack-up tolerance which is quickly becoming industry standard.

Pioneers of the Darkhorse Pro-Plug System

Darkhorse's innovative Pro-Plug System is often copied, but never duplicated. Our system far outperforms welding alone. It is is truly the cornerstone of our success and reputation.  All our proprietary bearings and races are now available exclusively through Darkhorse.

Properly Balanced Crankshaft

Our precision balancing method has proved to our dealers, and their customers, the benefits of a properly balanced crankshaft from Darkhorse Crankworks. Since 1980, we have been perfecting our processes, constantly reviewing and improving. This method equates to the smoothest crankshafts in America.

Crankshaft Vibration Analysis and Runout Measurements

Since 1980, we have performed extensive testing on crankshaft balancing and vibration analysis. We have concluded that the most important unit of measure is:

 Total Indicated Run-out at each main bearing race and flywheels that are precision balanced to each other 

Runout measured at the end of each shaft is simply a byproduct of those measurements.

Darkhorse Crankshaft Craftsmen

Over the years there have been many businesses who attempt to follow our processes, utilize our techniques or claim to have the same quality as our Darkhorse Crankworks ® products. What they do not have is the knowledge & experience of our team of machinists, engineers and craftsmen - experts in providing the solid, quality products in a time frame you deserve.

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I haven’t talked to you since you did that Twin Cam crank for our shop Blower King which was unbelievable! Thing is seriously smoother than a brand new Milwaukee 8, and a helluva lot faster/scarier/crazier!

Thanks!  Dan Cheeseman VP Klockworks


Remanufactured Crankshafts

Darkhorse is the PIONEER in offering “full service” to pressed together Harley Davidson® and Buell® crankshafts.  We offer superior remanufacturing and assembly services of the entire lower unit. Our focus is on tighter tolerances and upgraded precision parts. 

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Darkhorse Crankshaft's Focus

Let us take care of the foundation to your build, so you can concentrate on all the upper end details. We don't claim to be a one-stop shop. Rather, we are the highly qualified specialists in cases and cranks, our roots go back to Knuckles, Pans & Shovels along with ALL Sportsters! We let top end professionals and trusted motorcycle dealerships take it from there.Because our focus is crankcases and crankshafts, it forces us to continually develop and engineer our line of supporting precision parts to compliment and build a stronger foundation for today’s high output engine builds.

Machining Specs

Darkhorse machinists certify all three versions of our H-Beam Chromoly connecting rods before they are installed in any crankshaft. Our domestic and Carrillo con-rods are forged in the USA, finish sized and inspected by our machinists three times before final assembly. With centerlines machined to within .0003” of each other and being the only rod that you can provide a .001” stack-up on a remanufactured crankshaft, they are fast becoming the industry standard.Our precision balancing method has proved to our dealers, and their customers, the benefits of a properly balanced crankshaft from Darkhorse Crankworks. Since 1980, we have been perfecting our processes, constantly improving and building on success. Our dealers and customers know that this method equates to the smoothest crankshafts in the country.We true all crankshafts to within .0015” total indicated run-out at each main bearing race and guarantee them to stay within  .0005” for 2 years and unlimited miles. 


Our oversized and stepped crankpins allow us to save more OEM connecting rods and provides us flexibility in crankshaft configurations and building combinations that no one else in the industry can come close to. 

All work must be accompanied with a Remanufacture Work Order online form . A Dealer Application must be submitted, approved and on file prior to completion of work. Our procedures do not include the cost of parts. Please do not assume it will be all-inclusive. The crankshafts and cases we work on range from brand new to very old. It would be impossible for us to have set flat rates for our procedures.  Contact us if you require a quote prior to beginning work on your project.

Darkhorse Crankworks shall not, under any circumstances, be held liable for consequential damages, including parts not sold by Darkhorse Crankworks, labor not performed by Darkhorse Crankworks or loss of profits.  Installation of any aftermarket part, including parts and services by Darkhorse Crankworks, may adversely effect the OEM vehicle warranty.


You folks did the crankshaft and case work on my 2003 FLHRI engine for Baisley in Portland. I am very impressed how smooth this engine is even though it has 4.125” cylinders on it. It is running 120 hp. and 123 torque.

Thank you for a great job!  Rob Lien, Oregon


True Balance

We have decades of experience building, blueprinting and balancing Harley Davidson crankshafts. This knowledge in balance factors, allows us to tailor a crankshaft for your riding style, engine design and its intended RPM range.

What Is Dynamic Balance?

Dynamic Balance is defined as, "The state of equilibrium in which centrifugal forces, due to a rotating mass, do not produce force in the shaft and so vibration is reduced."

A Balancing Act

All Darkhorse Crankworks' flywheel assemblies are both static and dynamically balanced. Each individual part is balanced which equates to our flywheels in their assembled form dynamically balanced, pure physics and simple.

Imbalanced FlywheelDynamic Balance
The illustration to the above, shows Darkhorse Crankworks' corrected and dynamically balanced flywheel. Each individual part has been balanced using the exact same ratios, which moves center of gravity in parallel with flywheel center and the sums of all parts are then
dynamically balanced. We do not use the automotive method, (spinning at 500-750RPM) that is reconfigured and loosely adapted to achieve balance in your crankshaft. At Darkhorse, our procedure insures that each flywheel is balanced to < .5 ounce/inches for all street bike versions. We guarantee this because we are balancing each individual flywheel, not an assembly that can get a varying input caused by inconsistent crankshaft trueness between the balancing procedures and final assembly.  An automotive crankshaft’s total indicated run-out will not change from balancing to assembly. While a Harley-Davidson cycle will change almost every time - especially in a shop where main bearing tolerances are not strictly held under .0015".

Automotive Balancing Versus Motorcycle Balancing

Automotive-based equipment balances long one-piece crankshafts with multiple rod journals that cannot be disassembled. You are not able to balance of each individual rod journal, shaft and associated counter weight. Whereas a spin balancer achieves a dynamically balanced automotive crankshafts in large volume. Spin balancing an assembled Harley Davidson crankshaft with a bob weight to achieve a dynamically balanced flywheel is not the best available option to balance your Harley Davidson crankshaft assembly.

Imbalanced FlywheelDynamic Imbalance
The illustration above, shows a dynamically imbalanced flywheel. This flywheel may be static balanced as a unit, but not dynamically balanced. This means neither end would fall due to gravity, but having the weight in opposing areas would make it want to shake since the center of gravity is not parallel with the flywheels. Using automotive-style balancing means that the connecting rods must be removed. The crank is then reassembled without rods, trued to within given specs, spin balanced with a bob-weight, disassembled once again, rods and bearings replaced and then it must be reassembled. It then must be trued to the same identical spec it was spin balanced which can throw the whole process out.

Crankshaft Balancing and Vibration Analysis

Darkhorse Crankworks' research on crankshaft balancing and vibration analysis also leads us to an often-debated topic in direct regards to Harley-Davidson crankshafts.  What is the amount of acceptable run-out and where to measure?  Our stance on this issue has not changed or wavered since 1980. The most important unit of measurement is at each main bearing race. This is where one primary source of vibration is introduced from what may very well be a properly balanced crankshaft if not true.

We true all crankshafts to within .0015” total indicated run-out at each main bearing race held on centers and guarantee them to stay within  .0005” for two years and unlimited miles. 

To only look at the end of the pinion shaft for your overall tolerances is unacceptable and irresponsible to the crankshaft and the entire engine and drive train.  The run-out measurement at the END of EACH shaft is extremely important, but is typically a by-product of run-outs at each main bearing race.

At Darkhorse Crankworks, we continue to focus on perfecting our processes which equates to the smoothest crankshafts in the country.

Physics - Pure and Simple.


Thanks to Darkhorse Crankworks for preparing the perfect crankshaft: pinion shaft runout close to zero paired with vibration-free running condition.

Thank you very much and best regards from Germany!  Armin Jung, Ratingern, GERMANY