Nighttime, my bike runs better at night alsio.

 

Like 'rfranz1952' said, Cold air is more dens. When it's cold, out you could run it richer if you think you needed to.
On my old 2000 1200-C, and just about all the Harley guys I run with,can see a improvement in performance when it cools down out side.....

 

I love the way mine sounds on a cold morning.

 

The amount of power out of any combustion engine, either Diesel Cycle or Otto Cycle (gasoline engine) is dependent on the combustion temperature, the exhaust temperture as well as other things. The greater the difference between the combustion temperature and exhaust temperature the greater the power out put. Also the colder the air the more dense it is and thus there is more oxygen per cubic foot to combine with the fuel so you can burn more fuel which is the basic concept of a turbocharger. So yes with colder air you will get more horsepower.

 

Most of the posts above are correct. As a pilot of 35 years, I can attest to the effects of air temp on performance. First off, air gets more dense as it cools. An airplane gets airborne easier/quicker in cooler temps because of the increase in air density. Cooler air is "thicker" and lifts the wings more efficiently than warm/hot air. I have flown both carbed and injected planes. Carbed engines definitely show an increase in performance in cooler temps. Injected engines also show minor increases, but not as much as the carb. Flying can also be a wake-up call about the effects of exhaust gas temps in relation to fuel mixtures. Playing with the mixture control shows immediate changes in the EGT. More fuel = lower EGT.

To answer your question......YES. Your engine will deliver more HP in cooler temps. Now noticible it is in the HP range that we work with would probably not be enough to make a difference in overall performance, however.

 

from my experiance with race cars its not so much the air temp. as it is with the fuel temp. colder fuel along with cooler air should create 2 to 3 % more hp.but as the saying goes more air,more fuel,more spark more power but then you need a good exhaust to complete the package

 

Cold air does indeed make the bike run faster... But it doesn't have anything to do with density... It runs faster because it is sofaking cold in Idaho right now, that I just want to get home right away and drink a beer [8D]

 

Yes.. The colder the air in.... the better.

 

Actually with colder air, density altitude decreases,another way to put it, in higher temperaturesair moleculesexpand making fewer air molecules in a given volume. Air is denser in cooler temperatures becausesmaller molecules can pack into a given area.
A good example in the motorcycle world is you will notice it requires more carburator choke to restrict the amount of air entering the engine and more fuel to compensate for the denser cool air.

 

Here is why cool air is in fact more dense than warm air

PV=nRT (Ideal gas equation)

This is unrefutable, don’t ask me to explain.

Where P = Atmospheric pressure

V = volume of gas

n = mass of gas in question in moles

R is a constant

T is atmospheric temperature

If you want to know the volume a given mass of air at a given temperature and pressure you divide through by P

V=[nRT]/P

Where P is atmospheric pressure, T is atmospheric temperature and R is a constant.

If you would like to know the mass of a given volume of air at atmospheric pressure, and a given temperature then divide through by RT

n=[PV]/[RT]

since P stays constant and the volume of a given area of air which we wish to deduce the mass of is going to stay the same, lets say the volume of a 1200cc motors cylinder, which for our purposes would be…… anyone? Anyone? Bueler? 600cc. Therefore, since R is a constant for each gas, then as temperature increases, the mass of a given gas in a fixed volume at atmospheric pressure will decrease, and as the temperature decreases, the mass of a given gas in a fixed volume at atmospheric pressure will increase.

This is one of the basic tenets which govern how the working fluid (air) in a gasoline or diesel engine, or any other internal combustion engine works.

Now that we have established that cooler air = denser air

Since at a lower temperature there is a higher mass per unit volume, and at higher temperature there is a lower mass per unit volume. (see equations above)

Now, the question really is, does this increase in density consequently increase the horsepower??

if i can, i will answer that later, as that is a more in depth question which should call in to question the heat transfer happening in the motor, as there is a cooler atmosphere outside the motor wherebythecylinder (jug)is conducting more heat away from the motor, as well as a question of thermodynamics and combustion.