Harley-Davidson Limited Water Cooling Patent

Very often, it’s well after the facts that one can find out what a manufacturer has in mind to improve its products.

In this case, in 2010, Harley -Davidson patented a system to prevent its air-cool engines from running too hot and creating a risk of exhaust-valve seat distortion and even head cracking.

A possible remedy investigated by Harley-Davidson would be to “wrap” the exhaust valve seat with a hidden liquid cooling passage running water. Why water and not oil? Because water cools better than oil.

The system would be made of small radiators and an electric water pump. Of course, getting a patent doesn’t mean that Harley-Davidson will exploit it any time or even ever on his new models. But at least we know that Harley is preoccupied by the heating issues created by bigger air-cooled engines and tres to find a way to make them evolve without changing too much its Big Twin engine design.

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33 Responses to “Harley-Davidson Limited Water Cooling Patent”


  1. 1 Drake Jun 12th, 2012 at 12:20 pm

    Very interesting. But any future to this?

  2. 2 burnout Jun 12th, 2012 at 12:43 pm

    IMO not enough area will be cooled. Not even a good “quick fix”. peace

  3. 3 Lyle Jun 12th, 2012 at 12:48 pm

    Why not water cool the whole head?

  4. 4 Fritz Jun 12th, 2012 at 12:52 pm

    It is better than nothing but why not go to a totally water jacketed top end? I like the engineering of the V-Rod but don’t have arms and legs long enough to allow for ache free 12 – 14 hour riding days.

    You can beat several problems at once (noise muffling, superior cooling allowing use of crappy CA gas besides increased longevity). A big radiator is pretty ugly but maybe the engineers can hang it underneath the motor and transmission like the Oil Bud system. I have a lot of confidence in the engineers providing the bean counters and marketers don’t stick a knife into their good work trying to save or make a dime here or there.

    Are there that many people out there that prefer straight or traditional air cooling on a big engine in a heavy bike? What do the other blog dogs think about this?

  5. 5 Steve Carr Jun 12th, 2012 at 1:40 pm

    Liquid cooling the heads would be a “cool” idea, and could be done in a way as to not change the looks of the engine to any drastic degree. I’m all for it.

    Steve Carr

  6. 6 Lloyd Fuller Jun 12th, 2012 at 1:51 pm

    Direct injection would accomplish the goal without a radiator, and make more power to boot!

  7. 7 a 1 cycles Jun 12th, 2012 at 2:05 pm

    direct gasoline imjection is awesome!! but expensive…and harley always take the cheap fix over the right fix..a v rod powered bagger is an easy fix.re configure the engine for more tourqe and less hp..easy fix

  8. 8 CafeSportyTC Jun 12th, 2012 at 2:06 pm

    it can be done well enough and even keep the aircooled “fashion” enough to shut some of the die hards up for a while. even the die-hards at Porsche finally gave in and realized that water cooling even just the head is enough for Hi boost applications. (i.e. 935, 959). if you keep asking more and more from the same system somthing is going to give eventually.
    These heads wouldn’t require a huge radiator, and like Fritz said maybe it can be run under the bike covertly. even then now you can combine both an oil cooled and radiator into one unit and have the best of both…(now the oil wouldn’t need alot of cooling due to the head largely being cooled by the water now)
    Harley can keep their soul even with water cooling the heads… and if thats enough to force someone from not buying a new harley, that’s their problem. but thats just my opinion..

  9. 9 GuitarSlinger Jun 12th, 2012 at 2:27 pm

    Point #1 Air cooled motors are a thing of the past , offer zero benefits and should of been abandoned years ago . If it were not for the Xenophobic Harley ‘ Faithful ‘ the Motor Company would of done so decades ago .

    Point #2 No amount of Direct Injection etc will ever resolve the front/rear cylinder cooling dilemma , nor the quandary of appropriate cooling on excessively hot days or at altitude

    Point #3 IF the engineers would put their minds to it in conjunction with the designer …. smaller , more efficient and better looking radiators are more than a possibility

    Point #4 IF H-D would go the full Water Cooled motor route , the engines would immediately gain HP Torque better MPG , quieter noise levels etc e.g. Water Cooled is a WIN WIN …… well excepting those XenoTechnoPhobic Luddite H-D Faithful I already mentioned

    Point #5 This partial fix shown in the patent would barely have any effect on the motors and in fact will most likely prove to be just another mechanical mess to deal with when maintaining the motors e.g. It aint worth the Time or the Money for the little that’d be gained from this

    Having said that . I seriously doubt the Motor Company has the cojones to Do the Right/Smart Thing ….. so it’ll be another few decades of those under powered , over weight air cooled dinosaurs selling in the showrooms until …….. either the H-D faithful wise up ….or Harley Davidson goes the way of the DoDo Bird

  10. 10 alan sharp Jun 12th, 2012 at 2:47 pm

    They got no choice, but to copy the victory engine oil,air cooled, big power, time to retire,old push-rod engine…………

  11. 11 wolf Jun 12th, 2012 at 3:30 pm

    I always find it interesting how some people are so against Harleys. They must spend countless hours finding all sorts of reasons for not liking this or that about them and creating whatever logic they can dream up to support thier thoughts and views. What a shallow life. If you don’t like the bike, just go away and buy something else. Odds are you will complain about that other bike company too. We all know people like that and I for one choose not to ride with them or even be around them if I can help it. That is part of my freedom as an American. Along with freedom of speech comes my freedon to not listen to them.

    Motorcycles in general are toys. Some use them to make a living but most don’t. I love the look, the feel, the sound, the ride, the history and many more things about Harley. That is why i buy them. If I want to go fast through the twistys I would buy a crotch rocket. If I want to go off road exploring I would buy a dual purpose bike. If I wanted to …….. you get the picture. I want to ride beautiful roads at a slow and enjoyable pace with my girl on the back and feel that air cooled twin chugging away along with my friends and thier Harleys. That is why i buy Harley. I don’t trash the other bike styles or companys for what they build. I just choose to buy what I like. I totally respect anyone who buys a bike and rides the way they want to with it wether it be racing (on a track), off road, dual sport, etc. i have little to no time for those that choose to ride a certain bike style and company and then spend all thier time trashing what ever someone else rides because it is different from thier thought. I just walk away from people like that and take a cruise on the bike I choose to ride and on the roads I choose to ride on and with the people I choose to ride with.

    “And that is about all I got to say about that………”

  12. 12 roscoe Jun 12th, 2012 at 5:58 pm

    Water cooled heads in a motorcycle are nothing new. The Kawasaki Vulcan already has this. I think it is a great idea. Just hide the radiator and you can get the best of both worlds.

  13. 13 U. Dick Jun 12th, 2012 at 8:05 pm

    I love the old atiquated HD’s too. But the reality is that this is a attempt by HD to put a bandaid on a gunshot wound. Way back in 1993 (remember the VR1000 project and all the ol bikers bad mouthin it as the death of the aircooled HD?) or so the scuttlebut round the camp fire was that by 2000 all HD’s were going to be watercooled in order to meet emission standards……Well fast forward 12 more years and they seem to have dodged that bullet time and time again. That WILL change sooner or later and well its getting late. I see this as an incremental segway to gain customer acceptance of a complete line of liquid cooled HD’s. A revolution derived HD motor is the future, I know I know….HD will lose its core customers..etc etc etc…I call BS on that. HD will for sure lose some that will look to custom builders for a big inch aircooled scoot, but what they’ll lose they’ll make up in new customers that are interested in HD lineup but wouldn’t but because of the lack of modern tech (and let’s face it they will have much better performance). Eventually big bro wont allow for air/oil cooled bikes via emmission/mileage regs and all mass produced aircooled motors will be a beloved part of the past (as far as new production bikes go) HD customers will accept this in time…..bummer I know but it is what it is my friends.

  14. 14 Mike Greenwald Jun 13th, 2012 at 8:16 am

    Is it time to resurrect the “NOVA” project?

    Adding a water cooled head of this configuration may cause an addition of weight to a heavy cruiser/tourer. One of the best applications of the v-twin was a ditch pump. Realizing that the ditch pump was reliable when it had water may be a consideration.The billet covers and mounting brackets offer endless customization possibilities.

    Durability of design and thermal dissipation may be in question here.

    At least Harley will anticipate water cooling electric motors and batteries for the Electro-Glide.

  15. 15 Tom Jun 13th, 2012 at 8:17 am

    Go Wolf…
    In my case its my one vehicle..
    I do not want to be in a air cooled box. ..

  16. 16 Boomer Jun 13th, 2012 at 9:06 am

    Oil cooling the top end works fine. Look at what Victory did in their early days. They stuck a radiator about 5 times too big to cool the engine and it over-cooled it so they downsized the oil cooler to something like what you see on HD’s all the time from HD or Jag. Oil cooling works and with the correct oil pump; there’s no need to have another, separate, liquid system. More oil in the engine means better oil longevity too. It’s a win, win, win with oil cooling. What a lot of folks don’t know about oil is that synthetic oil doesn’t transfer heat as well as dino oil. It can handle higher levels of heat before breaking down. So a good compromise is the 50/50 synth/dino blend of good quality oils. The Shell Rotella synth blend is a fantastic oil for this application. But rather that get into, yet another oil war, just knowing oil cooling works is enough. The rest is academic.

  17. 17 BobS Jun 13th, 2012 at 9:16 am

    Wolf, I like everything you said, but you realize that there’s no shortage of Harley riders who are just as guilty of spending countless hours coming up with whatever logic they can dream up to put down someone else’s ride right?

  18. 18 Jack Jun 13th, 2012 at 9:35 am

    Boomer,
    From all I have read, synthetic oil transfers heat better than dino oil. The uniform size of the synthetic oil molecules being the reason why. The fact that engines actually run cooler with synthetic is the result. There are a number of myths out there about oil
    Many of my friends run dino oil in their twin cam engines and have had excellent results as far as parts and overall engine longevity are concerned. Some claim to get slightly better gas mileage with synthetic, but so many factors come to play that calim is hard to verify. Anyway, I agree that most of the newer big inch bikes definitely could use a quality oil cooler at the very least.

  19. 19 Gunslinger Jun 13th, 2012 at 10:29 am

    @Wolf – I agree 100%. I’ve always said “2 Wheels is a good start” ;)

  20. 20 Jennz Jun 13th, 2012 at 10:59 am

    This is very useful to all motorcycle riders who owns a Harley or any bike. But I think some motorcycle manufacturers have this already on their bikes.

  21. 21 Maytag Jun 13th, 2012 at 11:39 am

    Search the patent, it shows the entire system. 2 small rads, 1 hidden in each lower with fans. The cyls on 110′s already have the pads cast in them for the special gasket a la XR1200.

  22. 22 mobile Jun 13th, 2012 at 1:36 pm

    Going back to my years of being a HD owner, we put an oil cooler from a Chevy Corvair mounted in front of the shifter on the frame down low and it made a diffence in the oil temp as a result of the exposure to the air flow, the cooler was about the size 5″‘x 10″ or ? now in those years 1972 I was riding a brand new HD Elecrra Glide and it was a great improvement in the cooling, I can’t remember but it may have been a transmission cooler for the Corvair ? if anyone has an interest it can be checked out by using a search engine to see what it looks like. In those days there lots of
    Corvairs in the wrecking yards so the coolers came cheap and they worked well ..after riding a HD for over many years I bought liquid cooled touring bikes with driveshafts .Nice to have freedom of choice .Live to ride and ride to live. ” mobile”

  23. 23 rumble Jun 13th, 2012 at 2:10 pm

    I agree with Wolf, as far as riding whatever it is that you like, but just because you like your Harley, you have no right to put down everything else- accept BMW riders, we all know those guys are dikz! LOL! but how ironic that Harley’s next logical step would be to copy Victory’s OHC v-twin. That motor runs so cool, and pumps out so much more power, that it prove theout dated pushrod design is laughable. Go ahead and love your Harley, just admit that you’re riding probably the worst bike out there, just because you think it’s cool…

  24. 24 RedBen Jun 14th, 2012 at 9:08 am

    I find it interesting that water cooled advocates mention MPG as a benefit of being water cooled, yet the v-rod gets worse gas mileage than an Ultra Classic with a 103″ motor according to Harley’s website. Not to say water cooled may not be able to offer MPG benefits, but it doesn’t appear to in the case of the V-rod.

  25. 25 CafeSportyTC Jun 14th, 2012 at 4:54 pm

    the v-rod gets its power at higher rpms….more revolutions means more fuel… simple enough right?

  26. 26 U. Dick Jun 14th, 2012 at 9:58 pm

    Aircooled engines must run richer than liquid cooled ones because they use a bit of unburned fuel to carry some combustion heat out with the exhaust (EGT) and to stave off detonation. The revo motor gets less mileage due to RPM and higher power output (state of tune) per cube. Ask any general aviation pilot how they cool hot running lycoming or continental aircooled aviation engines “full rich”.

  27. 27 CafeSportyTC Jun 15th, 2012 at 1:22 pm

    exactly U. Dick exactly

  28. 28 richard Jun 15th, 2012 at 7:10 pm

    Gas milage has worked it’s way into this conversation. I could comment at length about water vs. air cooled but won’t other than saying that water cooling is better in almost every way ( having said that, for my own reasons I’m still a Harley guy) but would like to make one observation regarding the MPG comments. My 2011 Road King consistenly gets between 46 and 50 mpg. On trips with my two Gold Wing (water cooled)friends, they average 32 to 37mpg. That does not support the idea of watercooled getting better gas milage than air cooled engines. There are a BUNCH of other things that facilitate fuel ecomomy. I don’t think water vs. air cooling has much of a meaningful effect.

  29. 29 Kevin Boyle Kustoms Jun 18th, 2012 at 10:54 am

    I have always thought since the inception of the BOLTED together sub section of newer bvagger chassis that a VROD motor would be DUMPED into the bagger line???

  30. 30 Woody Jun 19th, 2012 at 12:38 pm

    @richard, please keep in mind that the internal friction of a 4 or 6 cyl Gold Wing engine is higher than a V-twin’s, also the ‘wing’s 90° drivetrain turn at the rear hypoid takes away 5%-7% usable power over the Harley’s belt drive. Comparing an air-cooled & water-cooled belt-driven V-Twin would probably be more fair.

  31. 31 Ax Jun 21st, 2012 at 3:34 pm

    “a v rod powered bagger is an easy fix.re configure the engine for more tourqe and less hp..easy fix”
    Sure, a real easy fix. That’s why Harley had to get Porsche’s help just to get the engine streetable enough to use in what amounts to a street-racing bike. And of course we ALL know how HUGELY successful sales of the V-Rod have been.
    I don’t know why Harley-haters spend so much time on blogs like this. If you want a japanese bike, there are plenty of choices out there. Go buy one.
    As for what Harley should do, the more common-sense solution would be to chuck the Twin Cam entirely and go back to the Evo as a starting point for a new engine. It ran as cool or cooler than any water-cooled motorcycle engine. There are plenty of aftermarket manufacturers who have upsized the Evo; it shouldn’t be hard for Harley to figure out how to do it in order to satisfy today’s riders who demand monstrous engines that won’t cook their legs to a crispy brown.

  32. 32 barney Jun 22nd, 2012 at 9:42 pm

    H-D can build new bikes with all the ugly car radiators they can hang off the bike…I won’t be buying one. I will buy a pre-radiator H-D.

  33. 33 Rich Jul 11th, 2012 at 6:37 pm

    When Harley decides to go with a true “water cooled” engine, I’ll buy another Harley!

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