My bottom end STINKS!

CC_RIDER

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May 15, 2001
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#1
That came out wrong....

I'm having a tuning problem that I bet someone here can help me with.
I recently changed the jetting on my '97 KTM 250SX. It was set up with the stock configuration, 175 main, 85C needle (clip in third notch) and 75 pilot.
I had been running rich, not fouling plugs, but just a lack of throttle response in the midrange. I first changed the main jet and needle one step. (170M, 85D,3rd notch). This setup got my mid and top in good shape, but it was still rich on the idle and just opening throttle, so I changed the pilot to a 72.
I'm still a little rich and the engine bogs and or dies when I dethrottle / brake for a turn. I can gas and clutch it to keep it running, however it is very sluggish until the rpm gets up to about the normal idle speed. It will idle on the stand, which I like, my problem occurs just when braking for a turn after a hard run.

I think I'm still too rich on the bottom, judging by the plug. I thought changing to the leaner needle would be enough, do I need to lower it also?

I'm new to jetting so if you see an error in my procedure, please speak up.
 

Jaybird

Apprentice Goon
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#2
I think maybe if you change clip position first it can help you decide if you need a different needle. If you are close, but still a little fat in the top clip postion, says you need a new needle.
As to where to run the clip initially after a new needle, I have no clue. I've always assumed starting the clip in middle position on all needles.
I'd at least go back to the stock needle and work back from there. You still had two positions left to work with.