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03 450 Jetting help


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I have and 03 450 that I bought new. Ive never modded it much until recently when I got back into dirt riding. It has the airbox snorkel removed and holes drilled, a white brothers air filter and e series exhaust with all the discs in, and gray wire cut. Currently it has a 152 main, 48 pilot, 65 starter, 70 paj, 70 leak, and was 3.5 turns on the pilot screw. I have never felt any off idle stumble but just constant throttle stumble. When riding at constant throttle, 1/4 throttle, it stumbles but if I pull the choke it runs better, even when warmed up.

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What sea level are you at? Seems like your needle could stand to be raised or just go to a larger Main jet might be best. I am running a 170 Main in my 04, needle in stock position.

What position is your needle in?

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I am at about 600' above sea level. My needle is in the 6th out of 7th position.

From the top? If so, you for sure have too small a Main Jet. Avg. position of the Needle is in the middle, give or take a notch either way. Stock Main I think is 165 and yours is set up for a high altitude. I am around 500-600 Ft above as you are.

I would at least go back to a stock Main and maybe more, I went from 165 to a 170, and move your needle clip 3 notches down from the top. This should fix you up.

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From the top? If so, you for sure have too small a Main Jet. Avg. position of the Needle is in the middle, give or take a notch either way. Stock Main I think is 165 and yours is set up for a high altitude. I am around 500-600 Ft above as you are.

I would at least go back to a stock Main and maybe more, I went from 165 to a 170, and move your needle clip 3 notches down from the top. This should fix you up.

Ditto, I'd try a 168 - 170 main, clip #3, and fuel screw 1.25 - 1.5 turns out as a starter point.

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The clip is in the 6th from top now. would the 3rd from top be richer or leaner? I put a 168 main in, 48 pilot, 40 leak, and 100 pilot air jet. I also got an adjustable air screw. The air screw, leak, and paj are on order and due in on thursday

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3rd from top would be leaner, but everything interacts together.

Check this out:

http://www.thumperfaq.com/jetting.htm

Your the original owner, and your positive it is the stock needle....right?

I can't imagine why a dealer would jet a bike like that...but...well...you know how some dealers are... :/

Look for "color" on the top of the needle...red, or blue....like this....

http://www.pbase.com/jdjetting1/image/38163739

just to see if it may be a JD needle somehow.....

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Try this:

165-168 main; 152 is really lean.

3rd clip needle; 6th clip may have been to compensate for the very lean main.

45 pilot, 2 turns; I only find the need for a 48 when it gets cold (< 50).

40 leak.

No real need to mess with the starter or pilot air.

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