Jetting for higher altitudes

A reference for the PWK carbs...
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icepick
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Jetting for higher altitudes

Post by icepick »

Getting ready to take my 99 KDX 200 to Gunnison Colorado elev. 7000+ ft
I'm currently running a 158 main, 48 pilot, and clip on the 3rd groove, FMF Gnarly, and FMF Powercore 2 located in Tulsa Ok, elevation 700ish feet, any advise on jetting for higher altitudes?
Thanks


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John_S
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Jetting for higher altitudes

Post by John_S »

Even though this is for a 2016 KTM 200 its still interesting to see how much jetting changes with elevation and different temperatures. Pick the Oklahoma current temp and elevation and your Colorado trip temp and elevation and see how much the jetting changes for that bike. Not a whole lot probably especially if its cooler in Colorado at 7500' because you would lean out for elevation but richen up in cooler temps. At the same temps maybe 2 down on the main, 2nd clip, 1/2 turn more out on the air screw to start with.
That chart from top to bottom on each setting is air screw setting from seated, pilot jet, needle, needle clip, main jet.
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ohgood
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Jetting for higher altitudes

Post by ohgood »

from what I remember in the charts, decrease main and idler 5% for 10x the elevation.

so for 1k to 10k feet elevation changes, you drop from a 50 / 150 combo to a 47/ 145 and then play with the needle and mixture.

every bike is different
icepick
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Re: Jetting for higher altitudes

Post by icepick »

Good info thanks!


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Vossman
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Re: Jetting for higher altitudes

Post by Vossman »

Please post what settings you end up at.
jackbombay
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Jetting for higher altitudes

Post by jackbombay »

I've been riding at 6500 to 10,500 lately, And I'm ashamed to admit I don't remember what pilot jet I put in, I think its a 35...

With a 152 MJ the bike blubbered above 8,700', dropped to a 150 and it was great up to 10,500 at WOT.

I am running a CEN needle, I had the clip in the 3rd position, but raised it to the second position (dropped the needle) when I went to the 150 MJ.

I have a 2006 KDX 200 with a FMF woods pipe and FMF silencer...
Vossman
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Re: Jetting for higher altitudes

Post by Vossman »

I'm at 6000 and got the JD kit with a 155 and 45 on the 3rd clip of the red needle. Rode it today for the first time and it was a bit rich but rode fine, just seemed like it should've pulled harder. It was warm and humid too.
I bet I can drop a size on all three and be ok here in town. It would probably be perfect come this fall.
Vossman
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Re: Jetting for higher altitudes

Post by Vossman »

I dropped the pilot to a 42 and nothing changed much, may have cleaned the bottom end up a bit. I will put in the 150 main now and see what changes.
Vossman
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Re: Jetting for higher altitudes

Post by Vossman »

So I dropped to a 40/150 and moved up a clip on the needle. Runs perfect at my altitude. In the mtns at 8800 it’s a little rich but still runs ok. A little bit of spooge out the tail pipe but nothing major. May try the other needle on the first clip.
tman
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Re: Jetting for higher altitudes

Post by tman »

I spoke to Jeff Fredette about my 95 KDX200. Riding at 6400 to 10k elevation. He told me : 42/150 jets, top notch on needle, 1/2 to 1 turn out on screw and Golden Spectro at 52:1 ratio. Haven't tried it yet. Waiting on new floats. Old ones were bent.
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