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Do you prefer Simple Air Cooled OR Liquid Cooled Bikes

Air VS. Liquid cooled

17K views 47 replies 34 participants last post by  sollee 
#1 ·
A good friend with a heck of a lot more riding experience than me, who rides an awesome FJR1300, recently told me he was jealous of my little old honda. He explained that while fuel injection, liquid cooled, full fairing, highly advanced bikes were very nice, he missed the simplicity of a good old carborated, aircooled bike.

For the record, he declined my offer for an even trade ;)
 
#2 ·
My Ninja 500 is water cooled and also has cooling fins, I guess that makes it both? That one never did come close to overheating; my Concours which is water cooled and has no fins and also has the engine completely enclosed in the fairing comes pretty close sometimes but I've always managed to keep it out of the red.

I guess it doesn't really matter to me all that much as long as the bike stays cool somehow.
 
#3 ·
Need to add another selection! The big Bandit is both air cooled and oil cooled! there is a small 'radiator' oil cooler on the front that the engine oil cycles through for additional cooling.

Basically, IMHO, having a 'coolant cooled' bike adds another system and each system carries its own potential for failure (thermostats, fans, pumps, seals, gaskets, etc).

But to be honest, so does an oil cooled bike - but only lines and the cooler itself.

Gotta say I agree with your buddy - less stuff to go wrong and easier to fix...but with those extra goodies you can really boost the performance!
 
#25 ·
Don't forget that the carb'd Bandit motors are impossible to destroy. If you do regular maintance on the valves and carbs you're set. Just change the oil when need be and don't drop the bike on its engine hard. I ride mine pretty hard if I'm going for a cruise and it eats up the road. The Bandit is an awesome performer. My buddy who sold me his Bandit bought a '03 Hayabusa and plans on getting back on a Bandit one of these days. He said the comfort and power was undeniable.
 
#8 ·
Add me to the category of liquid cooled. Like edger and hsartteacher, on hot days I don't need to worry about over heating in the stop and go traffic. I may be wrong on this but from what I seen most air cooled bike require a higher octane fuel.

As for being simpler, aren't many of the fuel injected/electronic ignition air cooled bikes coming with anti-knock sensors and that retard the timing and or change the fuel air mixture? Being the avid pessimist, there so many other things that can and will go wrong whats a few more things to break.
 
#10 ·
I have liquid cooled, but a friend has air cooled. He didn't want to do a stop/start 5 mile ride through my local town recently because last year his bike was on the verge of overheating, whereas I have never had a problem with mine overheating.
 
#11 ·
My Wing was liquid and I sold it when I bought my Ultra Classic.

There is Pro and Con to both. The water pump seal started leaking on the Wing and on that bike, it leaks oil both onto the ground and into the cooling system. I bought the water pump $130.00 and the guy paid a shop to install it. $400.00 later as they had to flush the cooling system to get the oil out, he was on the road.

Now for the Harley. It is an '07 which is the first year for O2 Sensors and in stock trim, I thought I had made a huge mistake. The bike was 3 days old and we went to Gatlinburg for the 4th of July. Sitting in traffic we couldn't stand the heat and I had to keep standing up as my inner thighs were burning.

I had ordered Vance & Hine's True Duals when I bought the bike, but they said they wouldn't put them on until I had 1000 miles. The bike was a week old, 660 miles and I pulled all the fluids and replaced them with, what else, AMSOIL. 30 degree drop in oil temps... a few days later (Bike is a week and a half old now) I took it in and had the pipes, Race Tuner Kit and the Screamin' Eagle Air Filter kit installed and Dyno Tuned.

Talk about a different bike... HP and Torque were up and the heat was down... Although not anything like in stock trim, it still gets a little warm when sitting still or on a slow ride such as Cade's Cove Loop which is a 5-10 MPG ride for 11 miles so I will put the Kuryaken deflectors on.

Doc
 
#12 ·
Aircooled. I like simplicity. Also, aircooled isn't as prone to overheating as you might think. VW used to advertise that their Beetles were superior to watercooled cars because they "couldn't" overheat climbing Pike's Peak in Colorado. I forget where I read it, but some aircooled bikes have been tested by letting them idle in summertime for half an hour and they were unable to get them to overheat. Remember an IC engine is basically an air pump, so it has a steady supply of air moving through it to cool it. The main reason bikes went to watercooled is because of emissions, watercooled can run leaner which leads to higher combustion temps, hence the need for more cooling. The aircooled can only stay cool if they run a little bit on the rich side, which the EPA doesn't like.
 
G
#13 ·
W/C MC's

I really prefer Water-Cooled Bikes but will settle for Air-Cooled (such as H-D BT's) or at least better still OIL-Cooled (such as my current Victory). I can't say I've been so nearly (all I've ever owned so far) lucky with water-cooled Cars but the 3 past W/C bikes I owned were beyond complaint (76’ GT750A, 78’ GL1000, 82’ GL1100) as far as service life and engine noise deadening. Never ever had a problem with water-cooled bikes – no leaks, no W/C component failures, never over-heated ever! Water-Cooled Cars/Trucks though? Forget it – one thing after another! Granted all 3 of my past W/C bikes were bought new – all my cars ever used, abused and worn out (the tie breaker!). I’d of loved a BIG displacement Harley (such as the long dead Nova 1500-Six) or Victory with W/C but doubt that will ever happen SO…. I do keep eyeing the Vulcan 1500 (since 1987 actually). I really DON’T see no disadvantages to W/C on bikes – compared to cars changing the anti-freeze now and then is a breeze. And because we use (AS directed) distilled water with a 50% Ethylene Glycol mix, there is virtually NO contaminate buildup IN the cooling system – stays dang clean (again compared to cars).

I love em’! Never have to worry about overheating! By 76’ Suzuki had removed the Electric Fan from the GT750 all together – the bike just wouldn’t overheat! It was the first modern ‘production’ (yes, not counting the Scott Flying Squirrel! :rolleyes:) bike with water–cooling, when it came out in 72’ Magazine Road Testers tried everything they could TO get it to overheat – they couldn’t DO it! I love ‘OVER-engineered’ machines! I too took that scoot out into Death Valley in July – was a posted 119 degrees in the shade at Stovepipe Wells – didn’t phase the bike in the least (but cooked the rider!). Now my past Gold-Wings would kick the Electric Fans in once in a Blue-Moon just to let me know they still worked – but not even remotely overheated! Nuff’ said.

LRG :cool:
 
#15 ·
well i have a 06 shadow,liquid cooled, carbs, never overheats but i do have to keep an eye on coolant level when riding in 120 degree days in socal. i'm still getting the gs1100 ready so i don't have any experience with large displacement aircooled bikes, although it looks like there could be an oil cooler installed. my zuma(scooter) is air cooled and has never overheated as far as i know :p i like the idea of water cooled myself. but until i get the gs running i'll wait to vote :D
 
#18 ·
I went backwards I guess. I went to the Big V-twin air cooled Harley. Yes, at first it was a hot one, but with the Performance upgrades of the Exhaust, Race Tuner Kit, Air Filter and Dyno Tuning, it is fine now..

Even my Wing sent some pretty hot air up in your face at a stop light.


Doc
 
#20 ·
That is such a generalized statement, and likely wrong. A properly maintained engine, air cooled or water cooled, has a quite long live. Probably longer than we care to own them for the most part. The killer of most engines is usually operator induced stress, often due to lack of maintenance.

A properly designed and maintained engine, generally has the same service life, by design, whether air or water cooled.

So total engine life is about the same, in general.

However, reliability isn't. Water cooled have exactly the same wearing parts as air cooled, but then add a few extra. Water pump, water pump drive, seals, radiator, thermostat, hoses, sensors, coolant. those extra parts never last as long as the engine. So besides having all the other possible wearing, breaking items as air-cooled, the water cooled has more parts to break. So from a reliability stand point, a water cooled is more likely to break down due to those extra parts.

Most small air craft use air cooled engine because of reliability. the less parts to break, the less likelihood of failure. In addition, a water cooled motor is heavier.

MY Nighthawk 750 requires oil changes and air filter changes, and chain maintenance. Having hydraulically self adjusting valves and no coolant, mean maintenance is simple. there is nothing to fail on it that isn't likely to fail on a water cooled motorcycle. The Engine is known for lasting in excess of 100,000 miles when maintained. The same motorcycle in water cooled, would also need coolant changes every 2 years, hose changes every 3-5 years, and a careful eye on the water pump seal.

If you are talking specific output, then water cooled is far better for making big horsepower. But a mild tune and low HP is also more reliable.

I would buy a water cooled bike, in fact, I like the Honda 919, pretty much a water cooled version of the Nighthawk. However, I have a feeling my Nighthawk, being air-cooled, will actually be around longer than the 919's. As water cooled bikes get older, their cooling systems get less reliable. Hoses harden and leak, the thermostats fail. A water cooled OLD bike is more likely to be overheated and destroyed, in my opinion, then an air cooled bike. That doesn't make the engine itself better or worse, but just that riders are more liely to kill an engine than the engine wear itself out.
 
#21 ·
I don't think I'm wrong... Although I agree with some of your points I don't see too many air cooled motors with 200,000 + miles without a rebuild when I know ther are many water cooled bike that have done that... That's what I was basing my General Statement on...One thing is... your Honda 750 is at or near the top of the list of air-cooled motors when it comes to reliability and longevity but you average that out with all the H-Ds and other air cooled V-Twins with the rear cylinder cooking and the average life span is lower than the average water cooled engine IMHO.
 
#27 ·
I guess the real problem is comparing apples to apples. Reliability and longevity are not the same thing.

There a favorable sides to water cooling. But strictly from reliability, i.e., mean time between failure, an air cooled motor has less things to fail.

Here's an example, a 4 engine airplane is likely to have an engine failure 4 times greater than a single engine. Even with the same exact engine all around. That's because there are more parts to go wrong. (The consequence of losing one engine in a 4 engine plane is a lot less drastic then losing the engine in a single engine). A water cooled engine just has more parts to fail.

I also say "A properly designed Engine". The Harley, with the rear cylinder behind the front, is not an ideal design from an engine standpoint.

I doubt there is a Goldwing out there with 200K miles that didn't have a failure of some sort that was repaired. For instance, timing belts fail without replacement. Since my NH750 has no Belt, it would go a lot further without maintenance other than oil changes and plugs (Common to both GW and NH) than a GW. I don't know, but do GW last 200K miles without a water pump failure? Hose failure? Radiator leak?

The GW is designed as a long haul bike, and at 20K and higher for a new one, repairs make sense. Make it last. My 750 cost me $2K, if it has a major issue, I would replace it as it is cheaper to replace than fix. That is why there are many high mileage GW's on the road. If a GW cost 5K, but was otherwise the same, I bet they would be recycled more too. I bet most air cooled bikes are not high mileage because they are cheaper to replace than fix. I don't see many people complaining about the air cooled engine wearing out. Most old bikes have electrical issues and alike, and are retired despite having a serviceable engine. Other issues retire them.

My understanding is Harley has many large E-glides out there with 200K. Probably because they are expensive too.

I stick to my opinion that air-cooled are as reliable and long lived as water cooled, assuming both are properly designed and cared for. So many air craft engines are air cooled precisely because of the reliability. (and light weight).

I was kind of random, but take it for what it is worth.

Are there benefits to water cooling? Of course. You stated them. Better engine clearances, better specific HP ability, more consistent operation.
But longevity and reliability aren't specific to water cooled engine.

I would rather have a well designed air cooled engine, then a poorly designed water cooled. And examples of both are out there.

But from a pure design standpoint, neither have an advantage.
 
#22 ·
There is Pro and Con to both engines as noted. However the statement about Air-Cooled not lasting as long as a Liquid-Cooled is generally correct.

I know of quite a few Wings with over 200,000 miles on them and a few with 400,000 miles.

I only know of a few Air-Cooled going over 200,000 and one is a Victory. I know of a couple Harley's going over 150 K...

The Air cooled engines are subject to more stress and wear due to engine temps. I have seen oil temps on my Harley in excess of 270 Degrees. Even with a hot running Liquid cooled, oil temps over 235 are rare and there is something wrong if you see those oil temps.

Doc
 
#23 ·
I've had both. For simplicity's sake, I prefer air-cooled. One less fluid to worry about when it comes time for maintenance, and if you spring a leak or drop a water pump or cooling fan on a water cooled bike, you're stuck. Also, on my Ninjas, it seemed that everything you wanted to work on required you to remove the radiator.

Having said that, I do like the longevity aspect of water-cooled engines. The coolant evens out temperatures across the heads and keeps them under control while idling in 110 degree heat. I can't help feel sorry for my air-cooled Virago in stop-and-go traffic in Dallas.
 
#24 ·
I second that on the water cooled for working on.

As for the Air-Cooled, most of your newer air-cooled engined spray oil on the bottom of the piston to help cool the combustion chambers down. Great for the combustion chamber, murder on the oil.

When I switched my Harley over to AMSOIL last year, at 660 miles on the OEM oil, I had an immediate decrease in oil temp by 30 degrees F. It was in the mid to upper 90's here in July 2007 and even my girlfriend noticed a difference in heat.... Then when the pipes went on, the bike was actually quite comfortable...

Doc
 
#28 ·
Air. Call me vintage.
 
#29 ·
There ain't too many Harleys without a rebuild with 200,000 miles... I doubt if there are any... Your notion of more moving parts being less reliable is flawed.. Case in point an OHV motor has more moving parts than a flathead... The efficiency of the OHV motor makes it more reliable than the flathead..
The metal on an air cooled engine gets put under much more stress than a water cooled engine due to higher temperatures... If that's not good enough for you we'll have to agree to disagree... Just don't tell me I'm wrong... Because anybody that knows anything about engines knows that as a general rule water cooled engines will outlast an air cooled engine... Why do you think almost all car engines are water cooled?? I'm done with this...
 
#31 ·
Longevity is not reliability. They are separate factors.

Flathead motors, made with the same modern materials as an overhead valve motor would be more reliable. You guys confuse specific motors with generic motors.

If you want to say this particular air cooled motor is less reliable than this particular water cooled motor, than the argument can be true.

A fan cooled, air cooled motor is reliable. The original Volkswagen Beetles, in their time, were very reliable. They did not overheat.

A motorcycle, without a fan, stopped in traffic, that's a different story.

Specific motors may or not be more reliable than another specific motor.

there are millions of air cooled motors out there that are extremely reliable. How many water cooled mowers do you see? When the oil is changed, the motors rarely fail. How much industrial equipment uses air cooled motors?

If fact, the most reliable (when designed right), is a 2 cycle, fan cooled, air cooled motor. Very few moving parts.

Cars are watercooled for a variety of reasons. NVH is one (noise/vibration/harshness). Another is specific output. I concede a watercooled motor can be in a higher tune, with higher compression. That does not mean it is more reliable. More powerful, yes. Cars are heavy, and they need more power than an air cooled motor can give.

But most aircraft are air cooled. Weight and reliability are the highest factors influencing them.

I don't know the the numbers, but it seems to me that very few people wear their motor out, air cooled or water cooled. Other parts of the vehicle fail before rings, bearings and cylinders are worn completely out of spec.

Poor storage habits, failing electrical systems, frame and shock wear probably kill more bikes then a worn motor.

Poor design is another killer. A Chevy 396 porcupine head often fails the valve guides because of a flaw in the design. The angle of the rocker arms to the valve stems puts excessive wear on the guides. The engine end up using oil, blowing a lot a smoke, fouling plugs. Despite being water cooled, the design is not reliable. There are quite a few water cooled bike engines with valve issues, pitting cam issues, and other poor design issues that shorten their life. There are Air cooled bikes with flaws too. But air cooling or water cooling is not the reason.

The truth of the matter, is the method of cooling is probably the least likely to be the cause of failure. Air cooled, Water cooled, most bikes have crappy electrical systems. Reliability in a bike will have more to do with things other than the motor wearing out.
 
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