cold weather and warm weather with 2 strokes

[twgranger]

with a 2 stroke when i gets colder out doors does make it run lean or does it make it run rich?

[speed20]

I believe the cold makes them run rich.....my dirtbike ran fine in the 65 degree weather, but in the 30-40 degree weather it loads up and doesnt want to run at all.

[200xman]

Cold makes 2 strokes or any engines for that matter run lean because the cold air is more dense.

[twgranger]

ok, now who is right?

[Mobular]

200xman has it right

[KASEY]

temprature has alot less affect on jetting than humidity and air density ,,and most won't affect jetting very much ,,unless you are on the edge of rich or lean then you will notice the change,,,,,, on a cold damp morning my stock 86 runs a little on the fat side (rich) but cleans up in the afternoon if i jetted it down one size it wouldn't change as much cause it would be closer to the middle of rich/lean , in the spring and summer months there is almost no noticable difference ,, its a delicate balance and i choose to stay on the the fat side,,,,

[Tri-Z Pilot]

Well, you are all about right. The cold air is more dense, and since your jetting is fixed, you could be running lean in the cold weather, but the cold can also make your bike run rich, if you are riding at a good pace, you are getting colder air on your radiators, which may be overcooling the bike, thus making it rich. On air cooled engines, I dont mess around anymore, I make sure my jetting is perfect, pretty easy to blow them up, as opposed to liquid cooled bikes. So I say get a dial a jet, or make sure your bikes jetting is spot on for the weather, but it is better to run rich, than it is to run lean.

[TimSr]

Both are right.

Cold engines run much richer, but cold air is much denser. As a result, your bike will run extermely rich, until it warns up to operating temp, and then it will run leaner.

Ive never changed carburetion for winter. They dont run MX in winter here which is the only time Im runningflat out screaming for extended periods of time anyways. Even when running lean you generally dont melt pistons at midrange, or trail riding, so Im not concerned even when doing harescrambles. If you like to get in the snow, spin the wheels, and make the engine scream for extended periods of time, it may be a different matter. If you keep in mind your running a little lean and keep your extended wheelspins at lower RPMs, your not likely to have a problem.

[twgranger]

how long does a spark plug last you? it seems like i go through alot of them. :( I had my main jet changed from a 470 to a 360.

[speed20]

the plug in my RM250 has been in it for 2 years (from what the previous owner said) and he said its never fouled on him.

[hondarox]

my friend had a 125 2 stroke in winter it would never run but in summer it werked great.

[yellowhammer]

who is your friend, surely it aint doody... cuz his 125 worked just great in winter as well as summer, just that his trike was a POS, and it always broke, cuz of what he'd do on her

[hondarox]

no johnny had one matthew