Dyno Dan

The alcohol expands and contracts greatly depending on ambient temperature. I have always noticed my engines running a little fat when the outside temp drops about 20-30* F. My air density gauge shows more oxygen, but the motor still seems a little fat. I feel that the fluctuation in the density of the fuel (from the expanding or contracting of alcohol) is the overriding factor to the engine's tune. This is very different from ringed gasoline engines i.e. motorcycle snowmobile etc. I have noticed this phenomenon on a consistent basis. Ed?

chunk t

If you are running near freezing or below, pipe temp is an issue. Until the pipe comes up to temp, your engine won't produce peak torque at the same RPM's as summer setting and the torque will be lower because your not able to take full effect of the scavenging or packing in the combustion chambr. So Initially you may think your engine needs to lean out to run right, but all you are really doing is quickly adding heat to the pipe. Once the pipe is up to temp the needle needs to get richend up. So I'd recommend starting fat and letting the engine & pipe work up to tem gradually.

In my experience winter driving isn't hard on the engine. It's the tuner

chunk

Cheezburger

iTrader: (2)

Kinda late, but yea i noticed that during winter runs too. The engine actually runs so weakly that i have to set it leaner than usual.

dannyg1970

iTrader: (18)

Since we are talking about cold temps,Its been getting pretty cold out here(So Cal) go figure I have a MR tuned ninja that i have been running with Oddonnel head with great results question is should i put the Magnesium head back on being that the temps have dropped so much? It's been fine just wondering if the mag head would allow more heat.

mungen

iTrader: (1)

i would not run my engines inthe cold it is hard on them. if u do put a sock on the head to kept it running at normal heat range.

Cheezburger

iTrader: (2)

A sock?? won't it catch on fire?

Semple

iTrader: (3)

I tried using an RB WS7T for its first track day when the outside temps were 7º celcius. It would not stay running at all regardless of tune. Probably too much pinch. I boxed all my RC stuff up until Spring after that day.

mungen

iTrader: (1)

no i know people that use them and its fine.

r1harper

iTrader: (24)

the thing that confuses people about tuning in the winter is they try to get there engine to a certain temp by leaning it out. by doing this they burn it up, seen it too many times.

Charles Godwin

iTrader: (2)

7*C, that's what we call warm over here lol . Tuning by temp sucks tbh, tune by feel, noise and amount of smoke