Air-Cooled Engine in Modern Frame

[MXLord327]

I think someone on this site was talking about this type of build not too long ago, I can't remember who it was.  This looks like a great project to me!!

http://www.off-road.com/dirtbike/project/project-24-getting-an-aircooled-motor-in-a-4stroke-frame-53113.html

[SachsGS]

I've done this a number of times and it's a lot of fun - both building the motorcycle and playing around with them afterwards.

[DangisMX]

I would like to ask if there are any advantages that an air cooled motor has over a liquid cooled one?

[Coop]

I would think simplicity of both the engine and parts required for the build, are the main advantages. Plus it's kind of cool to see an old air cooled engine in a modern chassis. Well, cool to me anyway haha.

[SachsGS]

The old aircooled motors don't stand a chance compared to the modern liquid cooled motors performance wise (obviously) but they are fun.Just like watching "On ANY Sunday" ,as soon as I hear the exhaust note and feel the different vibration of the motor I'm transported back to an earlier,simpler time in my life.All the old aircooled motors ask for is a piston and maybe some clutch plates now and then,quite the opposite of the "Nasa spec." maintenance regiment that modern racing 4Ts require.

[ford832]

Less power,old technology-what's not to like? It's not very logical,but on the other hand,it would be a cool project just because it is.I'd do it if time allowed-and may yet at some point

[opfermanmotors]

The old aircooled motors don't stand a chance compared to the modern liquid cooled motors performance wise

 

Except the big bores, the 81 Maico 490 stood against the KTM 525.

[factoryX]

With modern porting these motors are beasts.

[JETZcorp]

For me, the simplicity, appearance, and sound of the air-cooled engines are what do it.  I'm sure that liquid-cooled is much more effective (especially if you want to compare it to a late-model air-cooled engine, after they shaved the fins down by 50%).  However, the kind of riding I do generally involves higher average speeds and much lower average RPMs than motocross, so I simply don't need the extra cooling power.  The bike never gets particularly hot, why add moving parts and pump liquid to the top of the bike for cooling I don't need?  For someone making a serious bid at motocross racing victory, however, the situation is different.

[factoryX]

it depends on the bike, My dads 81 atc250r would get so hot that it would start dieseling.

[riffraff]

For me, the simplicity, appearance, and sound of the air-cooled engines are what do it.  I'm sure that liquid-cooled is much more effective (especially if you want to compare it to a late-model air-cooled engine, after they shaved the fins down by 50%).  However, the kind of riding I do generally involves higher average speeds and much lower average RPMs than motocross, so I simply don't need the extra cooling power.  The bike never gets particularly hot, why add moving parts and pump liquid to the top of the bike for cooling I don't need?  For someone making a serious bid at motocross racing victory, however, the situation is different.

That's why I like my '89 YZ490, simple air cooled engine and fairly modern chassis.

[DangisMX]

I see. Well I definitely understand why you guys like air cooled engines then . But what about overheating? If it does happen, do you get any warnings? I mean, when driving around on a liquid cooled engine, if it gets too hot, your antifreeze boils and you get steam coming from the radiator bleed hose, that's a good sign to take it easy for a while. But what about air cooled engines?

[MXLord327]

You would just start losing power.  Most amateur MX races are in the 15 minute range, and unless it was really hot outside, an air-cooled motor would be fine.  At pro speeds for 35 minutes, it would be a different story.  I think the biggest advantage would be for the guy that rides way out into the boonies - what happens to him on a water-cooled bike if cut cuts a coolant line or smashes a radiator?  Could be a long push back....

[SachsGS]

I think the purpose of the project is to illustrate just how complicated and expensive modern racing fourstrokes have become.You can't get much simpler then an aircooled 2T and I think Super Hunky is trying to hammer home the point that the sport is headed in the wrong direction.

[DangisMX]

MXLord327- Ah ok, I see. Thanks for the info.