Air-cooled vs liquid-cooled?

[CAMH]

I am looking at buying an air-cooled cruiser but I seem to remember hearing that air-cooled bikes overheat when sitting in traffic... Is this true?

What would you say are the pros and cons of air-cooled vs liquid-cooled for different styles of bike?

-Chris

[Hitcher]

Depends on what you're looking for. Engine heat frying your testimonials when riding around town can be problematic for both liquid and air cooled bikes. Other than that it's really just the Euro standards writers and their obsession with emissions that have any material effects for most types of bikes and riding conditions.

[Motu]

You would be hard pressed to overheat an aircooled bike around town - they can be thrashed offroad with little airspeed for hours no trouble...why would traffic lights bother them? A watercooled engine is more likely to overheat if there is something wrong with the cooling system...thermostat,rad cap,fan switch etc.

[Edbear]

I recall on a Child Cancer run from Cambridge to Hamilton it was a stinking hot day and we were drenched in our gear. The C50T had its fan cutting in on accaision but the air-cooled bikes were pinging and pinking and really suffering in teh slow trafioic. My old GSX600F was oil-cooled but even then it didn't like going too slow for too long. Harley are having a few issues meeting the emmissions with an air-cooled engine and there have been complaints of serious overheating of the rear cylinder despite fans and, I think oil-cooling for it.

Most of the time it's a non-issue, but there are times it will be a problem in today's traffic. Older air-cooled designs are less stressed and less highly tuned and don't suffer as badly. It really depends on your riding conditions day to day.

[FJRider]

I rode air cooled bikes through Singapore/Malaysia.Thailand ... 35 deg (C) the norm ... although higher temps were seen. The fitting of oil coolers into the oil system cured most of the problems ...

I never had any issues ...

[scumdog]

Harley are having a few issues meeting the emmissions with an air-cooled engine and there have been complaints of serious overheating of the rear cylinder despite fans and, I think oil-cooling for it.

.

Latest Harleys have a system whereby the rear cylinder is cut out when temps get high in traffic.

[Edbear]

Latest Harleys have a system whereby the rear cylinder is cut out when temps get high in traffic.

And I don't think it's much of an issue here, either, it seems most complaints are in the US.

[caspernz]

Air vs liquid cooled is not an issue, the biggest variable being the maintenance angle. If you run cheap oil in an air cooled engine, or skimp on the oil change interval, you'll have problems. Ask yourself whether a manufacturer would make a unit that would have big issues?

I've had all manner of bikes, air and liquid cooled, both will give issues under extreme circumstances. Got an air and oil cooled GSX750F at the moment and I've got no issues at all, even when stationary or ambling thru slow traffic.

[slofox]

Latest Harleys have a system whereby the rear cylinder is cut out when temps get high in traffic.

You sure that's not an "Undocumented Feature" Scummy?

[scumdog]

You sure that's not an "Undocumented Feature" Scummy?

Nah - but it's mainly iin the bigger bikes with fairings - and ones that get used in hot slow conditions like city cop bikes.

[Chooky]

My CBX didn't like sitting at the lights on a hot day.....:sweatdrop

[Coyote]

The big thing air cooled bikes have got going for them is simplicity. Fewer things to go wrong, no radiator leaks and water pumps and other bull.

Water cooled generally means performance because the engine can be kept at a consistent temperature easier than air cooled, which means engine tolerances can be made finer. Because of that, air cooled engines tend to be designed as long stroke, tractable and reliable motors since outright horsepower is not the focus. Torquey rather than revvy generally.

What will really decide it for you is riding them. Water jacket bikes restrain engine noise more so than cooling fins. You might think (edit: a quieter bike is) more refined, or you might prefer the mechanical noises. Quiet could be tame, loud could be barbaric. You can put any spin you like on it, just go for what gets your engine running.

Oil cooling is kinda an inbetween, basically air cooled but with an oil pump and cooler keeping the sump oil cool. Simple with a bit of a performance edge, but really a bit outdated as water cooling offers performance gains worth the extra plumbing. Still, I'm a convert to them having ridden my Gixxer project. Frikken awesome engines.

[Winston001]

Wot he (Coyote) said +1.

Water cooled = performance, closer tolerances, more complexity, quieter motor.

Air cooled engines have been around for 100 years now. They work.

[White trash]

Water jacket bikes restrain engine noise more so than cooling fins. You might think that's more refined, or you might prefer the mechanical noises. Quiet could be tame, loud could be barbaric. You can put any spin you like on it, just go for what gets your engine running.

Ummmm, you've got that all a bit backwards Dan.

[pete376403]

Water cooling also allows the designers to pack things in more tightly - eg the old Kawaaki 750 triples had about 50mm of cooling fins between each cylinder, a water jacket can shrink that down to half or less. Plus as mentioned, air cooling fins can ring like a bell, and noise emissions are as deemed as important as exhaust emissions. Finally water cooling allows tighter tolerances, again affecting exhaust emissions.
There shouldn't be any real issue with water cooling and reliability, it's ancient technology that has been proven on millions of cars

[Coyote]

Ummmm, you've got that all a bit backwards Dan.
I'm right on the water cooled bikes being mechanically quieter than air cooled. Edit: generally, not always.

And I still think a quiet bike is more refined, just my bikes show I'm a vulgar person :laugh:

[imdying]

Aircooled is very old tech. Much like the wheel, and there ain't much wrong with them. There's less to go wrong, that adds brownie points. On the flip side they often exhibit a little more noise from the motor, and are generally in a lower state of tune. One could argue that for a cruiser those are points for not against.

[Flip]

You sure that's not an "Undocumented Feature" Scummy?

When a big block gets hot it firstly drops 100rpm from its idle, then if it continues to heat up it starts deliberately missing, it intermittently stops injecting fuel drawing a cool charge of air through the motor cooling it.

[slofox]

When a big block gets hot it firstly drops 100rpm from its idle, then if it continues to heat up it starts deliberately missing, it intermittently stops injecting fuel drawing a cool charge of air through the motor cooling it.

That's pretty damn clever actually innit.

Even the gixxer gets up to cooling fan temperature in city traffic.

[willytheekid]

Ahhh watercooled

I remember getting stuck in traffic in central Dunners mid summer on my old GPZ900....she overheated and BLEW the radiator cap off!, which sent a geyser of boiling water spouting out...all over me!....fastest dismount of a bike I have EVER done :laugh:
I had to sit there and just watch my "Jug" of a bike spew boiling water and block traffic....funny now....but hurt like hell then (burnt legs and arm)

Now the old air cooled Guzzi.....she just gets grumpy when hot and the clutch turns to shit...otherwise, no prob! :niceone:

I loves the simple setups....and not getting third degree burns!

[jonbuoy]

Depends on what you're looking for. Engine heat frying your testimonials when riding around town can be problematic for both liquid and air cooled bikes. Other than that it's really just the Euro standards writers and their obsession with emissions that have any material effects for most types of bikes and riding conditions.

I think it was more to do with the USA (California) than Europe's euro standards putting the nail in the aircooled coffin.

[Spearfish]

Latest Harleys have a system whereby the rear cylinder is cut out when temps get high in traffic.

Is the rear the po or the tato cylinder?

[doc]

This water cooling thing is a passing fad, my lawn mower is air cooled. Well I think it is

[sinfull]

When a big block gets hot it firstly drops 100rpm from its idle, then if it continues to heat up it starts deliberately missing, it intermittently stops injecting fuel drawing a cool charge of air through the motor cooling it.

Now thats interesting, was gonna ask scummy where he found his wee gem of info that the rear just shuts down, but refined into this wording, i could see working !
My FXR has that option built in too now, it's called an EV51