Gas Mileage in Cold Weather

Bikerider

Bikerider

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I am getting pretty crappy gas mileage on these cold days we are having right now. All the reviews say that my bike should be getting 35 - 40 mpg ... but I seem to get around 25 mpg. Can this be due to the cold weather?
 
Carbed or injected? My old carbed bike gets awful mileage (as low as 20 mpg) while riding around town this time of year. It goes up to 45 mpg on the highway in the summer.
 
Number of factors for this. Winter formula gas, colder/denser air, shorter trips. I would say my economy drops about 15-20% on average during the colder months (as in now) compared to 20+C summer months.
 
regder said:
Number of factors for this. Winter formula gas, colder/denser air, shorter trips. I would say my economy drops about 15-20% on average during the colder months (as in now) compared to 20+C summer months.
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Colder /denser air is beneficial, better economy. But as riceburner pointed out, harder to reach optimal temperatures. Engines require different combustion ratio at different temperatures. A fully warmed engine is at its maximum efficiency
 
RockerGuy said:
Colder /denser air is beneficial, better economy. But as riceburner pointed out, harder to reach optimal temperatures. Engines require different combustion ratio at different temperatures. A fully warmed engine is at its maximum efficiency
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The best fuel economy I've ever received on my old FZ6 was riding in Colorado at huge altitude, i.e. thin air, no power though. Hopefully someone smarter than me can better explain it, but my basic understanding is that combustion is generally done at a somewhat fixed stoichiometric ratio. The thinner the air, the less fuel used. Denser air requires more fuel to meet the stoichiometric ratio.

I could be way off base though
 
regder said:
The best fuel economy I've ever received on my old FZ6 was riding in Colorado at huge altitude, i.e. thin air, no power though. Hopefully someone smarter than me can better explain it, but my basic understanding is that combustion is generally done at a somewhat fixed stoichiometric ratio. The thinner the air, the less fuel used. Denser air requires more fuel to meet the stoichiometric ratio.

I could be way off base though
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Stoichiometric ratio is fixed in a perfect world but in the real world it fluctuates. As mentioned earlier, when the engine is cold it is less efficient, requires more fuel per air ratio. That's why in caburated bikes there is a choke switch. This richens the mixture while engine is cold. In FI bikes this is programmed in the ecu. It automatically richens the mixture for a minute or however the manufacturer want it to be.

Engines are complicated than you think. This mixture also changes as the rpm changes. That's why there is 2 different pilot jets in carbed bikes. At higher rpm it requires a richer mixture than at lower rpm.

At Colorado what's happening is your engine does not have enough air to burn so it will drop the amount of fuel going into the engine, thus reducing power. I don't know if your bike is FI but I have a feeling it is. In FI this is all done by the ecu, in a carbed bike your bike with run bad at different altitudes.
 
Run the bike leaner and problem solved ;)
but on a serious note, you can always move away from stock spark plug type and go for one that'll operate with the colder air.
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