Idling the bike in cold weather can cause condensation which can leave small amounts of water that will freeze and the next time you start your bike below freezing your bike could be running without any lubrication.
If you haven't run the engine since your last ride you are better off to just pick up a Battery Tender for about $30 bucks and it will be ok untill this weather warms up.
Some charging systems will not properly charge the battery at idle speed.
A good way to tell for sure is put a volt meter on the battery while at idle. If the voltage is over 12volts, while at idle rpm, then you're ok. But Sin has a good point about condensation. When gas burns, it forms water and if the engine doesn't reach a temperature high enough to boil it out, in the form of vaper, then it just stays in the engine.
Well I guess it depends on what you mean by frozen.
Last week was 1 or 2 below 0 celsius here in London and my bike reached normal operating temperature at idle after 15 minutes.
I don't know whether I had water left in the engine but the bike seems to be running allright.
What I was talking about is if the bike is only idled and not ridden it will not get hot enough to remove the water that came from condensation. You may believe it is at operating temperature but the oil is not hot enough to disperse the water vapor.
When or if you start the bike and it is freezing 0 Celsius or 32 Fahrenheit the water (now ice) will not allow lubrication for your engine "especially if it has a oil tank" and it may appear all is well but you could be damaging your engine without proper precautions. Its important to change your engine oil more offten if you ride a lot during the cold.
Fortunately 99% of the time my bike is in the garage overnight and hopefully we'll not get more than a bunch of those days where one has to worry about the fact that it is to friggin' cold for your oil to get to the engine!
Just so busy with so many projects. Work, garbage disposal, 4-wheelers, Harley-Davidsonforum, football ect.... I was wanting to maintane the the charge in the battery without having to take it out or installing the Tender right now, just by idling it for a while.
Good point SIN: probably do more harm creating condensation, cause i was only thinking of running it long enough to keep a charge in the battery so that i don't have the hasseles of a dead battery.
Guess i'll have to get off my a$$ and get theTender or jr. tender installed, like I told myself back in October and continue to wait for the spring thaw to ride.
Still haven't decided on which one I should go with?