The rumors that Harley-Davidson has been eying a liquid-cooled motor design have always been in abundance, and 10 years ago we saw the company test the waters of that pool with the Porsche-engineered lump that was found in the V-Rod. While the VRSC line may not have been as big of a success compared to the other models in Harley’s line-up, the water-cooled bastard child of Milwaukee still seems to sell in the tens of thousands each year, even after nearly a decade of only cosmetic revisions.

Faced with an aging demographic, an uninspired motorcycle line-up, and 21 takes on the same motorcycle design, there’s a push internally at Harley-Davidson to break-out and find a new way to engage riders, especially younger riders. The core ethos of change seems to start at the motor itself, and Harley-Davidson has already done the rounds at various electric motorcycle and drivetrain companies. There also exists amount of external and internal pressure over Harley’s pervasive use of air-cooled motors, and now whispers of a water-cooled v-twin power plant have gotten louder in Milwaukee. With those rumors now reaching a boiling point (see what I did there?), Harley-Davidson has patented a very clever way of adding liquid-cooling to its iconic v-twin motor design.

Creating an intricate cylinder head that has channels that liquid coolant can flow through, Harley-Davidson’s shown solution to its air-cooled problem is a very elegant, and clearly centers around hiding the radiators, pumps, and hoses that normally are an eye-sore with liquid-cooled motors. However, it would seem the USPTO has granted Harley a fairly broad patent, which on its face seems to cover any sort of cylinder head cooling system for v-twin motorcycles, which makes this a nice piece of intellectual property for the Bar & Shield.

Putting the radiators in the leg shields of the bike, Harley-Davidson’s solution is to have the piping follow the forward section of the frame, and finally drop down from the fuel tank and into the cylinder heads. Once inside the cylinder, liquid flows around the valve ports before heading back out to be cooled again. With each cylinder head getting its own line of coolant it will be interesting to see if Harley-Davidson implemented any sort of system to account for temperature differences between the forward and rear cylinders.

Of course the bigger part of this news is whether we’ll see a liquid-cooled bike in 2012. Some rumors suggest so, though recent CARB filings haven’t tipped off any such model…yet. Once thought to be an untouchable element in Harley-Davidson design, the fact that the American company has patented this technology suggest that there are no sacred cows in Milwaukee. It will be interesting to see what comes to fruition now from this process.

Source: USPTO via Moto-Infos & Cyril Huse

  • Balzaak

    Welcome to the 70s!

  • Keith

    if true it’s about dang time they got into the 21st century.

  • BikePilot

    Ducati did almost exactly this with the ST2 IIRC (air cooled cylinders, liquid cooled head more or less).

  • What do you mean when you say “leg shields”? Do you mean the pods on the Ultra Classic? Those aren’t on very many models…

  • Rob

    ST2 was air cooled, it was actually the ST3 that was 3valve (air cooled heads) and water cooled. Not saying this is going to sell any more Harleys, but atleast its a push in the correct direction.

  • Odie

    @Keith – No, no. Not the 21st…that would be to much to ask.

  • buellracerx

    …and the XR1200 was born (oil “precision” cooled heads)…3 years ago lol

    interesting, though, that the twin cam is depicted vs. the sporty EVO. Really an ingenious design, much CFD & testing, I’m sure.

  • Greg

    ‘Merica, fuck YEAH!

  • Nobody

    Now that standard Harley models are breaking into the 60hp club, water cooling is a must.

  • Steve

    I would love to buy a Harley. If only they would build a motorcycle that would do something. Harley Davidson…..I know, a name change is in order….how about Hardly Ableton? Don’t get me started, I could go on for hours. I know,… lets play dress up and look like “Billy bad ass” with our stomachs pouring over our belts, week end go-tee’s and big scouls on our faces. We could pretend we are Marlin Brando or Dennis Hopper. We won’t tell anybody we got beat up alot in high school. C’mon it’ll be fun. Ok, I’ll stop….but I could go on……Leaking, slow, expensive, loud, obnoxcious, heavy, ill handling, dangerous piles of crap. Water cooling one would be easy. Ride it off a pier. Don’t worry about sinking, you can use the fat girl on the back for a float.

  • Kevin

    This could be as revolutionary as the rubber engine mounts in the 80s!

  • BikePilot

    Rob, the ST2 wasn’t entirely air cooled – it had liquid cooled heads.

    I think this, if ever implemented, is just a minor evolutionary change to allow the bike to tolerate traffic/Harley-rider paces with less overheating concern and meet ever more stringent emissions standards.

  • Bad Ass

    Don’t be so negative Steve. If you work hard and quit running your mouth, you may be able to afford one before they push dirt over you!


    Hey Steve,
    It’s nice to hear all those ancientclichéss you’re digging up, they go farther back than I do. You really need to get a life, you must be real lonely in your sheltered world where you can only repeat myths and oldclichéss.
    Hope you have a happy life, I’ll go ride my ancient bike now…

  • Tom

    Bad Ass obviously hasn’t been shopping for Harleys lately because affording one is easy. Now, being dumb enough to actually buy one that’s not the VROD, well, that is a totally different matter.

  • Dave

    Wow…just a different style of riding for different folks with different strokes…and NO amount of stereotyping will make any sense other than to illustrate ignorance. ANY riding is good riding, ANY racing is good racing and just what is BAD sex, anyway?

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  • Hate to tell H-D ….they are infringing on the patent of The Hull Effect Technology…
    I am Robert W Hull…inventor of that technology…that cools the engine and heads externally…
    at a much more rapid thermo-dynamics exchange…
    Any engine using radiators… oil …water …it does not matter…placed anywhere…falls under this patent.
    Something for the attornies to hash out.