Jetting and Needle question

A reference for the PWK carbs...
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BulldogKDX
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Jetting and Needle question

Post by BulldogKDX »

I am sure this has been discussed so please feel free to point me in the right direction. I recently picked up a 2004 KDX 220 and I am really enjoying working on it. The carb, jetting, rich, lean is all new to me and I appreciate learning more about it but again I am very new.

The previous owner lived at sea level (bay area, CA) and had a 160 main jet, 42 pilot jet and the needle clip in the middle. I haven't heard of this set up before, or at least a 160 main. I've notice it runs choppy and rough in 1st and 2nd at low/mid rpm and the power band smooth's out a lot in 3rd gear. I mistakenly moved the needle position down one position (I was thinking the opposite of what I should have done) and it made it worse last weekend. A little more boggy and an inconsistent hit when it came on which happened at inopportune times... I have since moved it back to the middle but think I try one position up to lean it out a bit. Am I thinking about this correct? I am thinking some responses might include, "try it then try something else if not". I get it, it's trial and error but I wanted to see if It made sense to start there then maybe change the jetting one at a time.

I have a Pro Circuit Platinum 2 pipe, FMF TurbineCore 2 silencer, Vforce3 reed (they're fine, I checked), air box lid removed, 32:1 pre mix and stock 33mm carb.

Thank you for any help or guidance. Cheers!
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KDXGarage
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Re: Jetting and Needle question

Post by KDXGarage »

Since you do not know if it ran perfectly for the other guy, just focus on how it runs for you.

Change one thing, then go ride. Write down the results.

Try to focus on getting the float level and pilot situated before worrying too much about the needle type, needle clip or main.
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BulldogKDX
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Re: Jetting and Needle question

Post by BulldogKDX »

Good call. The previous owner had zero idea and he thought it was jetted perfectly. Could've been for coastal riding but not for me in the central valley. I'll check the float level and go from there. Thanks!
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bufftester
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Re: Jetting and Needle question

Post by bufftester »

There is a sticky on setting your carb (linked in my signature). Follow it to the letter, in the order it says, and change only one thing at a time. The first thing you have to do is make sure everything is mechanically sound, then set the float height (16mm is the spec, but most folks find that 18mm is a bit more forgiving.) Once that is done work through the guide to set your pilot. AFTER the pilot is set correctly move on to the needle and main. Keep in mind that every bike is different when it comes to jetting, even when the bikes are the same, so somebody else's numbers might not be what you need.
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VTMTcowboy
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Re: Jetting and Needle question

Post by VTMTcowboy »

Definitely strange why the previous owner would have a 160 main in there. Stock is 145 main and 42 pilot and needle clip in the 3rd position. I'd get a 145 main, meaning go back to stock and start from there. Research and trial and error are your best bets to start with. One of the first signals of richness that I found on my 04 200 was excess un-burned fuel (spooge) coming from where the silencer and exhaust meet. It would do it at idle, but would cover my swing arm after an hour of riding in conditions where i was using 1/4 throttle and lugging. After that I dropped the main jet because I knew it was certainly running rich, but mainly focused on the pilot. I didn't touch the needle or clip position. After I cleaned up the spooge, I went to the idle air screw and tuned that. The idle air screw is important and shouldn't go un-attended. The bike now runs pretty solid. I left it a little rich, but for the riding I do that is fine with me. Good luck and enjoy the tinkering!
1997 KDX 220
2004 KDX 200
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Julien D
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Re: Jetting and Needle question

Post by Julien D »

The only reason I can see for needing something that fat on a 220 would be to compensate for an air leak.
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