Idle Adjustment Effect

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Oct 25, 1999
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#1
Should the idle adjuster on my Gas Gas' Keihin 38 have any other effect on the bike?

The jetting is stock and very rich. I am fouling plugs about every 20 miles but something odd happened yesterday. It seemed time to change the plug. I pulled it out but it looked pretty clean. The insulator was not black yet. So while I was fiddling with the bike, I adjusted the idle up by screwing the adjuster in hoping it might help my stalling problems. I could have sworn the manual stated the opposite to be true.

So I fired up the bike and started putting around and about 5 minutes later, the bike started cutting out, then died and wouldn't restart. I pulled the plug and it was very fouled. I put a new one in and it fired right up and ran well for about 15 minutes and then started to cut out or run roughly. It never did quit, however, and I was able to cover the last 5 miles home.

I haven't pulled that plug yet but I am wondering if the idle adjuster is affecting the jetting of the bike in general. I did have to screw the adjuster quite a ways in to get the idle where I wanted it. Looking at it, I have it screwed in probably farther than is normally possible because I broke the plastic head off so there is nothing stopping it.
 

KDXfile

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#2
The idle screw acts as a throttle stop so it shouldn't have any jetting effects.
You may have turned your air screw in too far; it should be 1-2 turns out for average conditions.
I would replace the idle screw and check the air screw position.
Have you pulled the bowl off to check what jets are in there?
For a 200, a good baseline would be 35-38 pilot, N1EC needle w/ clip in #3 or #2 position, & 175 main (40:1 mix).
 
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May 14, 2001
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#3
jetting

Mark,

I noticed you're in hoover, al. I live in helena and would like to know what you have your GG jetted at. I ride an '01 xc 250, and am a little rich off the bottom. Thanks
 

KDXfile

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#4
Shawn,
On my 99' EC200, the jetting is 38 pilot, N1EC needle #2, 175 main at 40:1 mix. These GG's like to be a little rich on the bottom but clean out when revved.
You could try lowering the needle one notch and backing your airscrew out a 1/2 turn and see if that helps.
Also, pull your jets to see what is installed. My bike came with a #45 pilot and Lemming's 200 came with a #35.
BTW, did you buy that 250 from Bill? Nice bike.
 
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#5
jetting

Mark,

Thanks for the reply. Yea, I got the red one from Bill. I love the bike. It came with a 40 pilot and 182 main. I changed them this morning to 35 pilot and 175 main. It seemed to clean it up a little. I think I might drop the needle tomorrow. Are you going to Clanton for the race Sunday?

Shawn
 

KDXfile

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#6
I'm going down to work the race. I went down today and it's really not that wet so it should be a good ride.