2004 KX250 still smoking on bottom end after dropping needle.

[Kawi4life]

I dropped the needle one position from stock #2 to position #1 to try to clean up the smoking on the bottom end. I was suprised to see the stock clip position was only one away from full lean instead of in the center clip. I also opened the air screw 1/2 turn more then stock to help lean it out. I just went out and rode it for the first time this year and after dropping the needle and opening the air screw, I still get smoke on low rpm even after ripping up and down a flat trail wide open through all the gears for five minutes.

Should I go smaller on the pilot then raise the needle back to stock? Or should I go leaner on both, needle and pilot? I don't wanna lose midrange power from too lean in the mid but need to cleanup this smoke and spooge on the bottom. Stock pilot is 52 according to my jetting chart. Can anyone with experience with jetting the 2004 KX250 help me out and give me some tips? I'm also using powermist 109 octane race gas with golden spectro. Would race gas require leaning all the jets for best performance? I'm gonna go out to the toolbox to see if I have any leaner pilots...

 

[Kawi4life]

Ahhh... I have a 50 pilot that looks like I tried to tighten it too much on one of my old bikes because it's slightly stripped in the slot the screw driver sits in to tighten/loosen it. I don't wanna chance getting a jet stuck in my carb. I also have a 48 but that might be too much of a jump from the stock 52?

I remember my 2001 RM250 came with extra jets if I can dig them up. But I think it was only main jets it came with. Looks like I'll have to just go to the shop and pickup a couple new jets or make a big jump to a 48.

 

[Studboy]

I would definately try the leaner pilots out, 2 sizes down isn't that uncommon.

 

[Kawi4life]

Ok, I just got back from the shop with a brand new 50 and 48 pilot. I have the time to put one in tonight, but think I'll run out of daylight to test ride it so I might just wait till tomorrow to mess with it. I dunno if it would be better to use the 48 and stock needle clip or 50 and one step leaner needle clip, lol. I'll report back after I've tried them out.

 

[Kawi4life]

Well I just couldn't wait till tomorrow to atleast put one of the new jets in so all I'd have to do is take it out and ride it tomorrow. Only took ten minutes to put the needle back to stock and change the pilot (didn't even have to take the carb off, just loosen and tilt it).

I decided to put the needle back to stock and just make the jump over the 50 pilot to the 48 because the way I see it, I was getting smoke on the very bottom and the mid to top was feeling spot on with no smoke. After I was done it was still plenty daylight out to roost up and down the trail to try out the new jetting.

I was a little worried that I might be going too lean jumping straight to the 48 (especially leaving the needle in the leanest position) and get those little "blips" when you punch the throttle from low rpm where it feels like the fuel cuts out for a split second but to my suprise it didn't and it has nearly cleared up all the smoke. After ripping on it then comming to a stop, it takes nearly a minute to get even a little smoke out of the exaust, but it's barely noticable so I think I have the jetting fairly close now.

I "might" even try one more step leaner on the pilot for shits and giggles since it's an inexpensive part and easy to swap out. But it's so close now, mabye another half a turn out on the air screw will make it "perfect".

Just for reference incase anyone else out there has a 2004 KX250 and needs to cleanup the smoke/exhaust spooge on low end, I've changed the stock pilot jet of 52 to 48 and went 1/2 turn out more over stock on the air screw and left everything else factory. It's nearly perfect now, I might not mess with it anymore. A little "hint" of smoke that's barely even noticable after idling for a minute might not be worth messing with.

 

[windyhill]

Man, thats just the info I've been looking for, mine will foul a plug while putting around with junior and smokes pretty bad. I think I'll pick up a 48 and 50 and give em a try. Thanks, JT

 

[Kawi4life]

Man, thats just the info I've been looking for, mine will foul a plug while putting around with junior and smokes pretty bad. I think I'll pick up a 48 and 50 and give em a try. Thanks, JT

Uh... I'd pick up a 48 and a 45 and skip the 50 if I where you. I think the 50 would be a waste of time considering you're fouling plugs. I did some more riding today. It was a little warmer out so the mixture richened back up a little bit and got a little bit of smoke back down on the very bottom end BUT, absolutley no spooge coming out of the exhaust. The silencer was completely dry. This is a first since owning a powerjet carbed bike, including my 2001 RM which spooged pretty bad out of the silencer as did my 99 KX250. Funny, when I picked up my bike from the dealer, they had to clean the rear fender because it had black wet spooge on it from them starting it.

Since much warmer weather is coming, I'm gonna drop down lower to a 45 pilot and see how it works and I also might richen the needle one step from stock to position #3 if I start to get any "blips" when excelerating hard through the midrange from leaning out the bottom. I thought it was kinda wierd that the stock needle jet setting on this bike is in the second leanest setting (position #2) and not in the middle. If memory serves me right, the stock pilot in the 97 and 98 KX250 was a 45.

I'll keep you fellow 04KX250 owners informed as I try different settings to get the jetting on this thing "perfected".