Jetting issue or something else?

battery

Member
May 25, 2005
18
0
I just bought a 1989 kdx. It has an fmf gold, 155 main jet, 48 pilot, needle in the middle clip. The needle is stock, I believe.
Airscrew is 1 1/2 turns out.

I get a stutter or jerk when I close down the throttle after accelerating. It's kind of like a rythmic stutter of the entire engine, different from the pop-pop sound I got before I changed the main and moved the needle.

Is this a jetting problem or something else? The bike accelerates smoothly and runs great with the throttle open.
 
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