Air-Cooled Engines Run Great in the Cold

[Travman]

Just a couple of comments about cold weather riding with a hopped up 1000 DS Monster.  The high today was in the upper 30's F.  I wanted to test out a new Ducati jacket I received for Christmas.  I was only going out for a very short ride, but ended up riding for well over an hour because the jacket worked so well and the engine felt great. It felt supremely powerful and tight.  How much stronger do you think an air cooled motor could be in cold weather?  Is there an actual horsepower gain?  (Too bad there was gravel everywhere.)

Also the clutch was much quieter without any of the super loud clanging. Why is the clutch quieter in the cold?

[sbrguy]

the faster you go the less clanging you will hear.

ever notice how the air cooled motors in the winter never quite warm you up as much as you thought they would.  afterall in the summer you are saying "damn i'm so hot on this bike even moving that if it was 0 outside i would still be warm" but when its actually 0 outside the motor doesn't quite warm you up as instantly as you would want.

[671M900]

I would guess that colder air is denser in oxygen, leading to a slightly leaner burn?

[Buckethead]

Super dense air charge + super dense fuel charge + super efficient cooling = lots of carbon and oxygen molecules doing their thing in the combustion chamber.

There were times when I lived in Maine that it was cool (50's) and rainy and, after warming up the bike while stationary, the cooling effect of the rain on the fins made it so that when I got to my destination, my oil temp was "LOW." Of course, you have to gear up for it, otherwise your blood temp can get "LOW" too.

Ask Travis (KnightofNi) how bikes do in the snow.

[koko64]

Just a couple of comments about cold weather riding with a hopped up 1000 DS Monster.  The high today was in the upper 30's F.  I wanted to test out a new Ducati jacket I received for Christmas.  I was only going out for a very short ride, but ended up riding for well over an hour because the jacket worked so well and the engine felt great. It felt supremely powerful and tight.  How much stronger do you think an air cooled motor could be in cold weather?  Is there an actual horsepower gain?  (Too bad there was gravel everywhere.)

Also the clutch was much quieter without any of the super loud clanging. Why is the clutch quieter in the cold?

I think any engine, air or liquid cooled, benefits from certain atmospheric conditions and struggles in others.

That beast of an air cooled engine in your bike would make a lot of hp for an air cooled engine, so getting rid of that excess heat would be important to maintain efficiency. Your bike might have liked the weather for more than one reason. Cooling is one consideration but so is the air density of the intake charge.

Drag racers have a saying that cold, dry, crisp nights, (low humidity) are good nights for making good runs and breaking records.

Dyno softwear will allow for correction factors for changes in air pressure, temp and humidity. A dyno operator might chime in with details, (BikeBoy.org has some good articles). When you dyno your bike, compare the actual hp for that day to the corrected run (if the tech will do it).

The clutch, just a guess, maybe an alloy basket expands less in the cold for tighter tolerances? Is your basket alloy?

[He Man]

i dont know about power. when i ride my bike in the 15degrees i cant get it past 130-140 degrees. Which is too cold. I ended up putting masking tape over  oil cooler just to help it warm up. it gets up to 160-170 like that, but the tape keeps falling off. I dont feel any power increase at all since it doenst warm up to temp.

[koko64]

Yeah too cold doesn't work either.

[Howie]

It's all about intake charge temperature assuming you don't run into fuel atomization problems.  Same with cars, particularly before before air mass sensors.  The difference is you really feel the improvement with a 400 pound machine, not so much with a 4000 pound machine.  Higher humidity and ambient air pressure will improve power too.  Cooler engine means cooler intake temperature when your fuel system is stuck in the middle of a V twin.

i dont know about power. when i ride my bike in the 15degrees i cant get it past 130-140 degrees. Which is too cold. I ended up putting masking tape over  oil cooler just to help it warm up. it gets up to 160-170 like that, but the tape keeps falling off. I dont feel any power increase at all since it doenst warm up to temp.

I have my cooler covered with a piece of black Naugahyde secured with black wire ties.  Much more reliable.

[Heath]

i dont know about power. when i ride my bike in the 15degrees i cant get it past 130-140 degrees. Which is too cold. I ended up putting masking tape over  oil cooler just to help it warm up. it gets up to 160-170 like that, but the tape keeps falling off. I dont feel any power increase at all since it doenst warm up to temp.

I've read using duct tape or aluminum tape works well.  No first hand experience though.  I know I want to tape mine because on my ride to work during the winter my bike will only go up to 160 or so.

[Artful]

Want to really feel a difference? Take a factory turbocharged vehicle out on a cold night. The typically inefficient side or top mount intercooler that causes heatsoak in regular temps works very well in the cold and you'll feel like you're driving a fire-breathing beast.

My old 1.8T GTI was meh in hot temps, but felt like it could pull stumps out of the ground when the temps dipped.

[yotogi]

Oh I miss my 1.8T Audi. That thing was so much fun on those cool dry nights.

[seevtsaab]

Want to really feel a difference? Take a factory turbocharged vehicle out on a cold night. The typically inefficient side or top mount intercooler that causes heatsoak in regular temps works very well in the cold and you'll feel like you're driving a fire-breathing beast.

+1

I've got a front mount, but cross flow interchoker, I do feel the extra pull at 10F-15F temps.
Of course the roads ain't always conducive to throttle abuse this time of year.

I would think the poor temp control of air cooled twins would present a compromise somewhere.

[Drunken Monkey]

My old 1.8T GTI was meh in hot temps, but felt like it could pull stumps out of the ground when the temps dipped.

Partially it was the lack of heat soak in the intercooler and partially it's that many modern turbocharged engines are smart enough to take advantage of the higher relative air density. They can even run higher boost is the ECU is smart enough.

And you should see a certain amount of increased power from FI bikes as well. They have an air temp sensor and (in theory) they will add extra fuel and enrich the mixture when the air is colder and denser. More fuel + more air = more power.

Carbed bikes... Not so much. They are just going to run leaner when the air is cold. And I remember seeing more than a few two-stokes seizing at races on cold mornings (Cold air = More air = Lean Mixture = boom.)

If your carb'ed bike's running a bit rich, then it'll get faster.

[Triple J]

My MTS1000DS would get 10mpg less in cold temps. It ran fine, but damn it ate fuel.

I also had to tape off the oil cooler in the winter or else it would rarely get above "LO", and if it did, it wouldn't get anywhere near 200* oil temp, above which it ran perfectly. If it was cold AND wet out, forget about it...no chance in hell of seeing an oil temp over 170 or so.

That motor seemed to run best between 60* and 90*.

[Scissors]

Colder temperatures are a mixed bag.

Positive:
Denser air means more oxygen.  As noted in a previous post, FI bikes can increase fuel trim to maintain the proper fuel:air ratio, resulting in more power.  Rich-running carb'ed bikes will also gain power.
Less humidity means more oxygen as well.

Negative:
Cooler engine means more cylinder wear.
Cooler engine means more energy being absorbed from the combustion chamber by the cylinder walls (and subsequently conducted to the fins).  Energy spent warming up metal is energy that isn't pushing on pistons.

Despite the energy absorption issue, the net result (in FI w/ O2 sensors and in carb'ed bikes running rich) is more power.

As a point of note, my '09 M1100 gets up to the 81-110 degrees celcius (178 to 230 fahrenheit) range when running at freeway speeds when it's in the teens outside (fahrenheit).  However, I believe this value is the head temperature, which is usually higher than the oil temperature, so my wear is likely increase.