Thread: Low mixture screw - running rich
07-02-2009, 09:46 AM #1
Low mixture screw - running rich
I'm running a little rich and want to make some minor adjustments to my Low-Speed Mixture Screw.
I recently adjusted my engine idle speed to increase my RPM, now it idles as per specs in & out of the water.The mark on my oil pump are aligned.
Because I'm running a little rich do I adjust my low speed mixture screw clockwise?
I think from memory ( I rebuilt it over the winter) I have it about 1-1/4 turns out from a lightly seated position.
07-02-2009, 10:19 AM #2
07-02-2009, 07:53 PM #3
So, is running lean better than running rich? I ride the ocean 95% of the time.
I did a little testing and noticed when I'm running lean, I get less smoke and my spark plugs have a tan-ish color (yes I'm using recommended spark plugs), it's stated that this is somewhat normal spark plug condition and when I'm running rich, I get more smoke and the tips look black, but not foul looking - maybe I'm over analyzing it or something!
I'm interested in what you guys have to say about this topic.
07-03-2009, 12:16 PM #4
here is the rule I use,,,,
Lean runs FAST, But rich will run all weekend.
this was adopted from Kart racing where guys jet so lean on the fine line.. the margin for error when the ( humidity, temp, air density change ) is as thin as a piece of paper, Then the motor has no buffer and seizure happens,
But staying a jet size or so on the rich side runs all weekend but is just not as fast,,, I would rather ride than rebuild..
07-03-2009, 06:14 PM #5
Interesting way of putting it - I finally tweaked the carb and have it set right in the middle. See how she go's.
07-05-2009, 07:21 AM #6
The Low Speed Adjuster is mostly used for Start up and Idle and the LS Fuel Circuit is in effect up to about 1/3 Throttle position. (although it still adds to the HS Fuel Circuit)
Rich/Lean adjustments at anything above 1/2 throttle position are more often done using the High Speed Circuit which, if your jetting is correct, should fall in between the 1/2 to 3/4 turns out from bottomed out.
Clockwise turning makes it Leaner
CClockwise turning opens it up to be a Richer mixture.
If you are working on an adjustment which is on the underside of the Carb. keep your orientation in mind.
07-05-2009, 12:57 PM #7
Some great input on this subject. I finally tweaked it and had it out over the weekend, she ran great. Throttle was very responsive.
07-06-2009, 05:42 AM #8
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Two strokes are more responsive when rich. That said, they idle much better (especially for extended periods) when lean, but hesitate slightly when first giving it throttle, and does not accelerate with authority as much as when rich.
If you have a 96 ignition the best of both worlds is to run a MSD Enhancer (increases spark) and richen them up some. For surf jumping...this is ideal.
Glad you got her running good!
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