Jet Needle Settings

[Quadjunkie]

What effect does moving the clip up and down on your needle jet have on your air/fuel intake?

[northwest Texas]

Lowering the clip raises the needle and allows more fuel in and vice versa

[Quadjunkie]

Are there any tests you can run to check for appropriate jet size and needle setting?

[northwest Texas]

I'll have to let someone a bit more savvy in that department talk to you.

Are you having a problem that is related to this you think?

[Quadjunkie]

No, my quad runs very well as far as I can tell. But if it wasn't running optimum I wouldn't know the difference. I am trying to learn as much as I can about my machine and quads in general. I really appreciate all of your help.

Thanks,

Chris

[Peteyman]

checking the spark plug is always a good idea
black -- rich, too much fuel
brown -- good, where you want to be
white -- lean, too little fuel and you will blow up

that's about all i can help with, sorry i dont know any other "tests"

[GPracer2500]

I prefer so called "seat of the pants" evaluation methods. I'll check a plug every once and a while. But to get really specific information from plugs can start getting involved. Yanking out a plug at any given time and taking a looksy doesn't always tell you much. To do it the way I think is the right way often isn't as appealing as the alternatives, IMO.

I find making back to back jetting changes and taking purposeful test rides works well and is the fastest way. What I mean by "pusposeful test rides" is something like this:

You just made a jetting change. Now you want to see if it helped or hurt. The first thing to think about is which throttle postion you need to focus on.

--Pilot circuit off idle to about 1/4 throttle.
--Needle ciruit 1/4 to 3/4 throttle.
--Main cirtuit 3/4 to WOT.

So for the needle, I'd find a place where I can run around in the 1/4 to 3/4 throttle range. High traction environments almost always work best. Ride around and really pay attention to the exhaust note and the sense of acceleration. Work the throttle back and forth in the throttle range you're testing. Pay attention to how "eager" the engine seems to rev. Do different things like hold a steady throttle, rolling the throttle around slowly, and making fast transtions from one position to another. Pay attention to how the engine responds to these different actions.

Did anything stand out? How did it feel? Now go make a change to that carb circuit and do it all again. Some changes--like turning on a choke just a hair or taping up some airbox holes--take a few seconds.

The specifics for what I look for and what kind of throttle manipulation I do for each circuit varies a little. Kinda' hard to describe well.

The needle is kind of a pain because clip postion changes take longer than any other change. And I find the needle circuit is the hardest detect good/bad changes in. There are some very specific and easy to interpret riding-type tests for the main jet curcuit. The needle is more of challenge.

$0.02