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Jetting: Are these settings ok. (JD jet kit)

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I have a 2006 YZ250F all stock except for the James Dean Jet Kit.

I live in Central PA. Our elevation is 1200 +/-. Temps here have been in the Mid 80's of late and kinda humid.

Here are my settings:

MJ 178, Red Needle 4th Clip, 40 Pilot, and 40 leakjet, Heavy JD oring on the AP & pumped is timed, fuel screw out 2 turns.

How the bike runs:

The bike hits hard down low in first and second gear and pulls clean throughout the rpm range. The bike seems to pull quickly through the gears, almost as if the gears were "shorter". The top end (3/4 +) pulls strong. The higher gears hit hard as long as the RPM is not too low, and even when there is some gear lugging going on it doesnt take long for the bike to say hang on. Part throttle runs at different increments and in different gears doesnt not stumble, burp or pop. There is some decel pop, actually kinda of two pops. Normal muffler decel sound with a softer, but a shorter crisper pop can also be heard. It does it more when the fuel screw is at one turn than at two. When the FS was at 1 the bike didn't hit quite as hard down low.

I have been at this jetting game on and off for two weeks. Previously I started at a 185 mj, blue needle, red needle, clip 1 to 7. I worked down to a 180 MJ then finally to a 178mj. The biggest problem I was having with the larger MJ was I could not get rid of a a 3/16 sputter. I tried working it out by using the different needles with different clip positions. I'm gonna stop. You know what i'm talking about if you have jetted.

Skip to the 178MJ testing with the red needle. I tried the blue at different settings and I was not getting good results. The bike drove okay ,but not stellar. I want to state I still had the stock 80 LJ installed at this time and the 42 pilot. I got a 40 pilot, back to clip 3 on the blue needle. The bike again ran ok, but stock actually seemed better. The 3/16 sputter was gone, but the down low hit was "delayed" when the throttle was whacked.

I put the red needle #5, and the 40 LJ in today. At one turn the sputter was gone, but the bike lagged when I hit the throttle hard. At 1/2 turn the bike came to life the instant the throttle was turned. Even from just off idle.

This is when I moved the needle to clip 4, but I had to turn the FS out to 2 turns and the bike just tears down low, mid, off idle and top. The idle doesn't hang except the rpm rises some when engine breaking down a hill in second gear. Is this normal?

I guess I would like some input from those more experienced than I just to let me know the bike is not too lean. I don't want to pop an engine. I have thought of putting the 42 pilot back in and adjsuting the fuel screw, and possible installing a 50 lj, but the bike runs strong. I feel the bike is okay as it is. The extra little, soft short popping sound on decel is new to me, and concerns me a bit as I was thinking I might have the pilot circuit too lean. I never heard it before today. Has anyone else heard it? I did correctly install the gasket at the mid pipe connector since it was sliding out. I was thinking maybe I was getting a small air leak at the joint.

If anyone has any input I would appreciate hearing it?

Personal thanks to Eddie for past help, Taffy's, Yamakazes, and James Deans posts and ofcourse his jet kit, and the helpful sticky posts by members linked over at thumperfaq.

Thanks Greg.

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Red #4 with a #40 pilot jet and 2 1/4 turns out, or #42 and 1 1/2 turns out. Either setting should not have a hanging idle.

It seems that your setting is very close to what you need at this point, and not too lean. The 3/16 throttle sputter should not be related to the settings down lower. Becuse the main jet is also affected by the needle tip (which is lean in this case), the #180 main jet may be worth retrying at this point.



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James thanks for the reply.

The 3/16 throttle sputter is gone with the current red needle, 4th clip setting and 2 turns out on the fuel screw. The idle doesn't hang when the throttle is whicked, it just rises some when descending a hill in second gear.

I will give the fuel screw another 1/4 turn, or put the 42 back in with a 1-1/2 turn, and give the 180 another shot.

Thanks Greg

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