Liquid vs Oil cooled

[colbycurtis]

I know everyone says HD and others who refuse to put radiators on their bikes are still in the stone age but I really need to ask does it really make that much difference? I was looking at the Victories tonight and the Yamaha Raider-S and they also are air/oil cooled HD has been doing it for years so does it really matter? I was thinking Yamaha has a reputation for motors that just last forever like Honda and kawasaki and Yamaha doesn't use liquid so I was thinking when you have a radiator the water flows through jackets and cools the motor then back to the radiator now I am no professional mechanic but I was reading the Yamaha Raider uses oil heres what they say about the Raider "Plated cylinders and forged pistons cooled by oil jets provide outstanding reliability and long life. Twin counterbalancers keep things smooth but rumbly."

So it has oil jets does the hot oil then go to a oil cooler like a radiator? if so I do not see the advantage over liquid cooled as a matter of fact liquid evaporates and steams oil doesn't so could not oil cooled be better??

Please correct me if I'm wrong on this thinking but I was a big fan of liquid cooled and now I'm wondering does it really matter. Also if your like most bikers who don't keep the bike more than a couple years before upgrading doesn't that make it even less of a factor?

[TJ900B]

After reading your question, I don't know where to begin.

There's a lot more to maintaining an engine constant temperature than life of the engine especially performance. Whether a fluid boils at a given temperature or not has nothing to do with its heat exchange rate. It is how fast a fluid gives up heat that influences how well it performs as a cooling agent. Coolants for engines are not just water but specifically designed chemicals for maximum heat exchange.

Without going into basic chemistry or physics, I can tell you the car you drive is not ancient technology and bikes more sophisticated than cars. In fact, its the opposite. Fuel injection on bikes for example is rudimentary compared to cars.

See many air cooled cars or oil cooled only?

Heat is the death of mechanical things. It causes the metal to expand and friction within the engine to increase. When hot the engine has to work harder to produce the same power and harder does take away from the life. There are three sources of heat in an engine, internal temperature, how hard the engine is working, and the ambient outside air temperature. Of the three, how hard the engine is working has as much to do with engine life as temperature.

Now if you follow this, there's no reason why you can't get as long a life out of a small air cooled engine as a liquid cooled if you limit all the factors. That's things like don't push the motor too hard, use premium fuels, and don't ride in excessively hot environments.

A liquid cooled engine simply allows the engine to have more flexibility in adverse conditions. If we all drove vehicles in winter environments, other than poor performance every engine would be air cooled. That isn't the case though.

When talking about this concerning motorcycles, its good to keep in mind the vast majority of the market is very low miles per year. Gas millage figures are high and a few mpgs one way or the other isn't that big a deal. Though the horsepower is low, the torque to weight ratio is very low compared to a car so losing some power isn't as noticeable. Ride a bike though in 95 degree temps, you can certainly feel the power loss.

Manufacturers make motorcycle to match the market.

The longest millage wise motorcycles are the touring bikes. With the exception of Harley all of these are liquid cooled. That's not by happenstance. Even Harley has put a sixth gear in the FLH to limit how hard the bike works. This wasn't just for comfort at highway speeds but it prolongs the life of the engine by reducing heat.

To put this in simple terms, a given design with the same parts and a given test parameter (how the engine is run), a liquid cooled motor will out perform and out live an air cooled or oil cooled engine. The variance comes from changing the conditions.

It follows, if you ride under controlled conditions and limited miles, an air cooled engine will make little difference as far as bikes are concerned. If you do high miles under adverse conditions, a liquid cooled engine makes a big difference.

Tj

[JohnnyZ]

Water cooled engnes have a larger jacket surrounding the cylinders as opposed to oil cooled engines. This reduces the cooling efficiency of the cylinder fins should the water cooling system fail. If the water cooling system fails the fins won't be able to dissipate the engine heat on their own. In an oil cooled system the cylinder fins are part of the cooling system. Water cooled engines have moving parts associated with the cooling system (i.e. water pump and associated components). Maintanance is higher with a water cooled system. There has been debate over peformance related to each system, but it really is a mute point since the engines are engineered with their specific cooling system in mind. Each system will perform as well as the other, however, since the engine requires oil anyway why not use it to cool the cylinders? Oil cooled engines do require a better grade of oil and a quart or two more. It really comes down to maintanance, the consequences of system failure, and which system your bike comes with

[colbycurtis]

OK after reading the two replies above I've swung both ways on the subject. I am still unsure about the subject. Here is why I ask. Probably in about 6 months or so I will probably trade my bike in for a bigger bike. The ones I am looking at so far are the Victory Hammer Air/Oil Yamaha Raider-S Air/Oil and the M109R2 liquid/Air. Right now without seeing Kawasaki's 2008 line up and going into all my personal reasons I have been leaning toward the Raider-S but heres my problem I do live in one of the hottest areas in the country. Last year we had 54 days straight over 100. I also ride pretty hard I have hit my rev limiter in 1st second and third a few times and open her up allot. So with all that I worry about the Raider not having liquid cooling. The M109R has had a few mechanical problems I have read about enough times to shy me away right now. The Raider is 113 cubic inches so it is a big motor I like the bike I just wish it had a radiator

[anrfknm]

i would not be afraid of getting an air/oil cooled cruiser. everything said above is true and if you were getting a higher rev'ing, higher performance bike it would matter a great deal. cruisers on the other had are milder running bikes and don't tax the motor like a sport bike or even a sport tourer. i've ridden air cooled bikes for over 40 years and never had one fail due to heat. if longevity is an issue, then, yes overall, water cooled motors will last longer.

[Pooker]

To me it's like having an out house vs indoor plumbing, black & white vs a colour TV, bias tubed vs steel belted tires, can opener vs an electric can opener.
They all work well and they all have a place in time,
NEW TECHNOLOGY.
How many Grand Prix racing bikes are "air cooled"?
Myself personally I prefer water cooled engines over air cooled any day and I live in Canada.

[honestlyinsane]

Isn't the vrod Liquid cooled ?
If thats the case isn't even HD saying its better ?
I think the advantage you are getting from air cooled enigines is inthe aesthetics (less crap on the bike) I think there weigh out looks vs. need. cruisers are still able to get the performance they need without liquid cooling so basically it costs less to build and looks better. Those are your only advantages.
By the way in a closed cooling system cooling doesn't evaporate and the boiling point is raised 3 degrees for every pound of pressure which usually means if you get the coolant that hot you other issues.

The oil jet technology you speak of is used in diesel engines also . but guess how they cool there oil.....if you guess through the liquid cooling system you would be right.

[msa1956]

Very interesting reading guys, a lot of it makes sense, I guess you have to look at what do you really want, and what kind of maintenance do you want to do. So enjoy it No matter what you pick, Ride hard, Live Long and Enjoy Life.

[Thullan]

Also to take into consideration, radiators on a cruiser is damn ugly! And if air cooled engines were that bad, would they still sell them a 100 years later?

[texrider]

Water cooled bikes deal with heat in a precisely controlled manner, by means of a thermostatic water valve and radiator fan wired to a temperature switch.

Heat is applied evenly throughout the motor to promote proper combustion, and proper expansion of parts to limit wear. Heat is removed evenly for the same reasons. The electric rad fan assists in maintaining control when moving slowly, and normal airflow is reduced.

Jap bike makers (Suzuki) saw the potential benefits of water cooling almost 40 rears ago, and very few don't have it nowdays.

Regardless of ceramics or plasma coatings, air cooled bikes are a low tech idea, IMO...

[CTRider]

Originally Posted by Thullan

Also to take into consideration, radiators on a cruiser is damn ugly! And if air cooled engines were that bad, would they still sell them a 100 years later?

Two reasons why air cooled systems are still used:

1) They're cheaper. On lower priced bikes, a liquid cooled system would add too much to the cost.

2) On cruisers, then engine is open. It's not in an engine compartment. As a result, the heat can escape and air can circulate around it when you're moving. If you don't do a lot of stop and go riding, there's not much of an issue other than a hot crotch and legs for the rider.

The fact is, it depends on your riding conditions. If you commute through traffic jams in hot climates, you'll want liquid cooling if you value the health of your bike. Sitting in 90+ degree weather in a traffic jam where you either can't or choose not to lane split is terrible for an air cooled engine. On the other hand, if the only sitting you do is at occasional traffic lights and the temperature seldom gets above 90, air cooled is fine.

[colbycurtis]

I found this searching Google.


Most modern internal combustion engines are cooled by a closed circuit carrying liquid coolant through channels in the engine block, where the coolant absorbs heat, to a heat exchanger or radiator where the coolant releases heat into the air, and so on, ad infinitum. Thus, while they are ultimately cooled by air, because of the liquid-coolant circuit they are known as water-cooled. In contrast, heat generated by an air-cooled engine is released directly into the air. Typically this is facilitated with metal fins covering the outside of the cylinders which increase the surface area that air can act on. It is worth noting that in all combustion engines, a great percentage of the heat generated (around 44%) escapes through the exhaust, not through either a liquid cooling system nor through the metal fins of an air-cooled engine (12%). About 8% of the heat energy finds its way into the oil, which although primarily meant for lubrication, also plays a role in heat dissipation via a cooler.

[plasma blue]

Get what you like, for cruisers air/oil are OK, (you're not racing)where you live you may want to add a fan or two to the oil cooling radiator.
Sure they aren't as powerfull but they still work. Stop & go traffic is not as comfortable, but if you keep it moving you are OK.

[okplayer]

Very interesting read. I live in Kansas City and I too am thinking about an upgrade next season. I was looking at the Victory 8-Ball but I fear the temperature factor as well. This summer we had over two weeks of 110+ degree days and I am not so sure that I want to trust an air-cooled engine with such. The 800 has done great, cant really say enough about how reliable it's been even though I sometimes runer a little hard. My co-worker picked up an M109R last week, nice bike but the riding position is a little awkward. I have only sat on it, it might take a while before I can talk him into letting me ride it. Let us know what you decide colby.

[crazydave]

+1

[ThomasE]

well all the new Hd s are cooking the hell out of the riders as the rear cylinder overheats easy..
AIr cooling works as long as the bike is moving and the ambient isnt too high.
But as I ride my bike in traffic and on hot days. I know for a fact that liquid cooling keeps my engine temp at much cooler temps than a ac system would ,, which means my engine wil last longer and power delivery is more consistent..
Now when it gets hot in your house do you prefer liquid cooling ( Hvac ) or the good old fashion air cooling ( a big fan)...

if you use the big fan the best place to be is right in front of it to achieve decent cooling.
IF you must have Air cooling on a bike, the best way to acheive cooling is to stick the cylinders in the direct air ,, such as a 1200 gs or guzzi twin.
on a v twin the rear cyclinder get almost no air flow.
and oil cooling does nothing if the bike isnt moving.

My vstrom uses air, oil and liquid cooling how great is that

[Idaho]

Colbycurtis:

Get the bike you want. Air cooled bikes have been around a long time and the sales continue to do well. If they did not work well the customers would have pursuaded the manufactures in another direction long ago. I am from New Mexico where it gets plenty hot and the sales of air cooled bikes down there is doing just fine. If I had the money for a second bike and I decided it was going to be air cooled, I would get a Harley. Personally I like the looks of the Victory better, they look great. But, in spite of the Victory's good looks and powerful engine etc., it is still a Polaris based product. Mucho bad experience with their products. But that is just me. Best of luck to you with your decision.

[Grumbler]

Originally Posted by colbycurtis

I was looking at the Victories tonight and the Yamaha Raider-S and they also are air/oil cooled HD has been doing it for years so does it really matter?

I personally *think* that it matters much more today than in previous years due to the stricter emission regulations. Meaning, the fuel mixtures are getting leaner and leaner.

Have seen too many complaints about 2nd degree burns from the newer Harley-Davidsons *unless* they're modified to run a bit richer. In fact, word is that there will be liquid-cooled heads beginning with some 2009 Harley-Davidsons.

The forthcoming Triumph 1500cc Parallel Twin is said to be liquid-cooled even though the current Bonneville America/Speedmaster range are air-cooled.

Incidently, my bud's '01 Suzuki Intruder 1500LC is air/oil-cooled, and doesn't have any heating issues, but his carbs were rejetted too rich (can smell the gas vapors when behind him) and averages 35mpg.

One more item of note, the GWRRA (Gold Wing Road Riders Association) was founded in Phoenix, AZ.

[JohnnyZ]

Water cooled systems are not 21st century technology. More like early 20th century , but then again so are air/oil cooling systems.

[Deeppurple52]

From my unscientific experience. It depends on where you live. In Phoenix it makes a big difference. During the summer I see virtually no H-D's during my daily commute across Phoenix. In the winter there are many more. My friends who ride them complain they are too hot to ride during the day. That may or my not be true. A co-worker of my wife parks her H-D in the summer because, she says, the engine heat is unbearable. Again, her opinion. There must be some reason why nearly all of the bikes on the road are metrics in the summer.