ORIGINAL: annie_himself
ORIGINAL: motopro
big mis conception to cold weather is to think you need to fatten in cold wheather ...in reality you often need to lean...i race here in michigan and on cold days under 20f i need to lean my motor to raise the engine temp....dont think of it as conventional 2 stroke ....ambient air temp is everything th e colder it is the fatter your motor will run
I know what you are saying but the air is thinner at 20F so you need to richen the mixture to compensate for the amount of air you will need. And wrap the head in foil.
So many things wrong in this thread.
Air gets denser when it's cold and contains more oxygen. That means you can burn more fuel ---> richen up = more power.
Tuning by engine temp alone is wrong. Richen it up until it starts to 4-stroke down the straigh and then lean out until it runs clean. That's when it produces the most power. If it's still running cold you need to put a smaller cooling head on it and you will gain even more power. (Wrap it in foil could work too).
edit:
Forgot to add that the effect of high altitude can be somewhat compensated by adding more nitro, it contains oxygen. That's also the reason you need to richen up when running higher nitro.