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I hit 106 today and still had tack to spare. Not a lot but I'm pretty sure that I could have gotten up to 110. My bike is still totally stock. I'm believe 100% that this was due to the temperature of the fuel in the tank. I can't back that up at all with any kind of explanation but I'm sure its a fact. On several occasions now I've put cool fuel in my bike and notice that I'm doing the same speed at 3k less RPM s. I'm still running 14t front, not shims, stock muffler, uncut fender, I didn't even have my bungee cord on today. I would love to hear any hypothesis to prove or dis-prove my theory. Try it yourself. I'm not condoning going over the speed limit. That would be illegal and unsafe. What I'm saying is take your lawn mower gas can and put it in a freezer for awhile and then put it in your tank and see if you can tell any difference. Be careful not to contaminate the food in your freezer and always was off the counter surface and all of your cooking utensils when preparing poultry or fish or Sal Monella may come pay a little visit to ya and kick your guts in.
 

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I have noticed that in the morning that my bike runs at lower RPM's. They make CO2 kits to blow in a cars air intake to cool the air, which in turn makes the car run faster. I don't think my wife would like for me to put my dirty lawnmower gas can in the freezer. LOL
 
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i heard the best time to get fule is at night time and if you always keep your fule above 1/2 tank or full is best your gas mpg will increase even more along with right tire psi i heard it on the radio im going to try that
 

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There is some truth to having cold fuel and getting better performance out of a gas powered machine. On racing cars they use a canister filled with dry ice and the fuel line coils around this canister before entering the carbs. Prevents a vapor lock condition and makes the fuel at molecular level change. A checmical change takes place wherin the fuel molacules seperate.
 

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The reason you are seeing 3k less RPM is your tach is messing up with temperature changes. The only way to go the same speed with a different RPM is to change gearing or tire size.
 

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Colder fuel can add more power, anytime the intake charge is cooler more air and fuel can fit (cooler=denser) and more power. However the ratio of rpm's/speed in a certain gear is ALWAYS the same unless the clutch is slipping.
 

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Or your tire is slipping because you can't get traction because of all that extra power from your cooler gas. Can you freeze gasoline? I doubt it but, ice cubes for your gas tank anyone? Haha
 

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I think what everyone is getting at, But can't remember how to explain is thermal expansion, The rule of thumb generally is matter at low temperature is smaller than the same matter at a higher temperature.

In conditions where your fuel is going to be cold, The air you are taking in is also going to be cold, Therefor you'll be getting more of them sucked into your combustion chamber, The more fuel for the fire, The bigger the fire is, therefor the better your bike runs.
 

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volume change due to temperature of petrol would be negligable. and if anything it would make the cat in ur tank meow more frequently and louder. as it heats and "expands" the air has to go somewhere. but i dont think that it would compress in any great proportions.
 

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Colder fuel doesn't vaporize as good as warm fuel. So I don't know really what to think of your statement.

It this was true, why would we need a choke? Cold chamber, cold air, cold fuel, but for some reason you need more fuel (or less air) to get the engine to start and idle.

Maybe I'm missing something.
 

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Interesting statement about the cold fuel, does fuel flow more slowly when its cold ? would it change how the engine warm up ?

Today its in the low 40's and my bike started right up with no hesitation (no choke). Once started the bike idle very low, less then 1000 rpm, try to apply choke and the bike just dies out. If I apply some quick throttle, the bike would die. I have to use the throttle very slow to raise the rpm. When the bike is warm, it idle at around 1500 rpm

What do you guys do when the bike is pretty cold ? Do you guys let it idle for a few minutes before going for a ride ?

Misc info on my bike:
Have full Yoshi exaust
Needle shim with 2 washers
snorkel remove from airbox
Kleen air system remove
 

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Cold fuel will simply not combust properly.

Think about it, the only any engines runs better when its warm, is when the fuel enters the hot combustion chamber it gets warmed up very fast, then the spark ignites it easily. Cold fuel = Bad combustion.

We have snowmobile here and when we start them at -25 celcius ( -13 F). We have to use the prime button (aka injecting liquid fuel in the carburator), because at that temperator, the fuel doesn't burn Right at all, lol.

littlemike said:
Interesting statement about the cold fuel, does fuel flow more slowly when its cold ? would it change how the engine warm up ?

Today its in the low 40's and my bike started right up with no hesitation (no choke). Once started the bike idle very low, less then 1000 rpm, try to apply choke and the bike just dies out. If I apply some quick throttle, the bike would die. I have to use the throttle very slow to raise the rpm. When the bike is warm, it idle at around 1500 rpm

What do you guys do when the bike is pretty cold ? Do you guys let it idle for a few minutes before going for a ride ?

Misc info on my bike:
Have full Yoshi exaust
Needle shim with 2 washers
snorkel remove from airbox
Kleen air system remove
 

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rayme said:
Cold fuel will simply not combust properly.

Think about it, the only any engines runs better when its warm, is when the fuel enters the hot combustion chamber it gets warmed up very fast, then the spark ignites it easily. Cold fuel = Bad combustion.

We have snowmobile here and when we start them at -25 celcius ( -13 F). We have to use the prime button (aka injecting liquid fuel in the carburator), because at that temperator, the fuel doesn't burn Right at all, lol.

[quoted text removed]
+1
 

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oooo, so many factors.

1.) the freezing temp of unleaded is roughly -120F. The flash point is -97F. This means that gas vapors will burn at down -97F, however, those vapors will be very slow to emit from the pool of gas....

2.) when gas, like all hydrocarbons, gets colder and colder, the chemistry doesn't change, but the molecular arrangement does and so the molecule still looks the same, with the same amount of Hydrogens, Oxygens, and Carbons, but they all line up in very nice, neat little rows in a lattice formation. This makes them harder to pull apart and mix with the molecules of air (N2 + O2 + etc, etc) for a nice combustion.

3.) cold starts: the colder your engine is, the colder the oil in the crankcase requiring more force to turn the parts in side (factor 1) - nor any oil in those parts cause it's all in the crankcase to make things move nice and smoothly-like. When the metal parts of the engine and carb are cold their tolerances shrink (the parts are closer together) and friction is increased (factor 2). When you set the needles in a carb, you should do while the engine is warm, which means they will be off (factor 3) - hot air -> cold air and needle settings are LEAN, which is why you need a choke.

So, to put all this together, and affirming what others have said, if you could run a warmed-up engine with COLD gas, you'd get more pep, if you're carbs were adjusted right, because you can fit more fuel/air in the cylinder - same idea as very tiny turbo. Yes, you will notice an increase in performance in colder weather. No, your RPM's will not be spinning lower (gear ratio is fixed), but might climb faster....

my .02
 
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