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My 2003 kit came with the following:

Mikuni main jets - 380, 390, 400, 410

Mikuni pilot jet - 32.5

Needle clip

Blue marked needle - richer 0-1/4 throttle

Red marked needle - leaner 0-1/4 throttle

Some people have received a leaner S4 nozzle at no additional charge when ordering from JD. I was told they would throw one in with my kit but when it arrived I was invoiced for it. If you order it elsewhere I doubt it's even an option.

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My 2003 kit came with the following:

Mikuni main jets - 380, 390, 400, 410

Mikuni pilot jet - 32.5

Needle clip

Blue marked needle - richer 0-1/4 throttle

Red marked needle - leaner 0-1/4 throttle

Some people have received a leaner S4 nozzle at no additional charge when ordering from JD. I was told they would throw one in with my kit but when it arrived I was invoiced for it. If you order it elsewhere I doubt it's even an option.

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Yeah later on, I asked jd about nozzle he sent one out too me free I forgot about that. Yours came with a 380 ? I belive that 380 is stock size. Oh Still_kicking , I'm betting your a tad rich on the needle.

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Yeah later on, I asked jd about nozzle he sent one out too me free I forgot about that. Yours came with a 380 ? I belive that 380 is stock size. Oh Still_kicking , I'm betting your a tad rich on the needle.

Yes, mine came with a 380.

If I remember correctly, the 03 came stock with a 420 main.

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The JD kit sounds good but you can probably find a whole kehin carb off any mid-late 90's CR250..

i guess when you add in the cost of the boots, jets and the whole carb maybe it is kind of pricey..but oh well!

Me personally I don't have no problems with the mikuni. I have thought about switching carbs, but I can get my mikuni jetted pretty darn good.

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At what elevation would someone need an S-4 nozzle?

S8 gets lean at 1000 ft depending on the temps.

Me personally I don't have no problems with the mikuni. I have thought about switching carbs, but I can get my mikuni jetted pretty darn good.
I agree. Have switched carbs a time or two. They all need to be jetted and I didn't have the miraculous results that others have had.
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I wonder why they would change the main for 03...

My guess is they probably changed the needle.

At what elevation would someone need an S-4 nozzle?

S8 gets lean at 1000 ft depending on the temps.

It works when using the JD needles versus the Mikuni needles. I have the S4 in my carb.

I agree. Have switched carbs a time or two. They all need to be jetted and I didn't have the miraculous results that others have had.

I've just never had one as sensitive as the TMX. I can get it pretty clean with the JD kit but slight temp changes make a big difference in how it runs and require AS adjustments.

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At what elevation would someone need an S-4 nozzle?

I'm also running the s-4 nozzle. I can't run the stock nozzle. If I run the stock nozzle bike runs soo rich even with the jd needle at the top clip . Which I have a ported/stuffed cylinder, ported/stuffed cases so I have had too run my bike soo much leaner. Right now im running 28.5 pilot, jd blue needle 2 clip from top, and 400 main. It seems pretty good but I just switched over too running strait 115 so I will hafe too rejet yet again.

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Gotcha. S-4 with JD needles and misc mods.

I've just never had one as sensitive as the TMX. I can get it pretty clean with the JD kit but slight temp changes make a big difference in how it runs and require AS adjustments.

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I can see that.

I was referring more to the guys who say they can ride a gear higher, best mod ever, "bike is a beast now" kind of stuff. I didn't have those kind of results. I noticed the 50 tooth on the 02 more than the Keihin carb. Promptly put the carb back on my 00.

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Gotcha. S-4 with JD needles and misc mods.

I can see that.

I was referring more to the guys who say they can ride a gear higher, best mod ever, "bike is a beast now" kind of stuff. I didn't have those kind of results. I noticed the 50 tooth on the 02 more than the Keihin carb. Promptly put the carb back on my 00.

i agree. the PWK isnt a magic"powernow" bullet, but it will make for a more pleasent ride at a wider temp range without having to play musical jets all the time. i got my mikuni ever so close, but a big ole' cloud rolled through, and my setting was off again. not so much with the PWK...plus the jets/needles are cheaper

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