When to adjust needle, and when to re-jet

[steffen707]

Okay, so you guys talk a lot about re-jetting. And what i understood that to be, was actually changing the jet that's inside the carb, to one with a bigger orifice, to allow more gas through it.

I was talking to a buddy that snomobiles a lot, and he looked at me like I ws crazy. He says the only jetting he does is to raise or lower the needle circlip, to richen or lean out the mixture.

Is the needle adjustment just for fine tuning, and the actual jet replacement for larger adjusting?

There was talk on another thread that these scoots are jetting close to lean from the factory to decrease emissions and if you're riding in cold weather, like I am in Wisconsin, that maybe I should fatten or richen up my mixture. Should I just do that with the needle?

[losthope]

needle adjustment controls mostly 1/4throttle to 3/4 throttle. main jet controls mostly 3/4 to wot

[Kenny_McCormic]

needle adjustment controls mostly 1/4throttle to 3/4 throttle. main jet controls mostly 3/4 to wot

That^

[steffen707]

ohhh, well thanks guys.

[Wheelman-111]

Greetings:

One more thing. I'm in the middle of a tuning process myself. My current jet is a 90-ish. For my setup it's a bit on the rich side. However a tad rich at WOT is a welcome influx of cooling mixture, just when the engine needs it most - high RPM and combustion pressures. Since my WOT operation is occasional and short-lived, I stayed with the richer jet but dropped the needle to its lowest position by raising the clip to the topmost notch. This obstructs the emulsion tube a bit more, leaning things out closer to correct MOST of the time. Results will confirm this logic. Or I'll learn a lot more.

[steffen707]

keep us posted wheelman.

[circusracer]

Thanks for all the helpful input.