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Discussion Starter · #1 ·
I'm new here, have an 01 raptor 660. Open air box with flow pro filter,
pilot jets 25
main jets 165, 170
needles on 3rd clip.

starts good, idles great, runs great until I get to 5th gear in the upper rpm's on a open road, starts to stumble above 1/4 throtle and have to back off to keep it going. Like it's starving for fuel or too much fuel. I live in utah at 4500 altitude. Should I try adjusting the needles first or change the jets?
 

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Master of the Electron
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15,635 Posts
You are too rich for that altitude - back off to 155L/160R and see what happens. Test by turning fuel petcock off and riding at 3/4 to WOT for a minute - as the float bowl empties you will run leaner and leaner - if you find it running better. briefly, this proves that you're too rich.
 

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I am unique
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I'm new here, have an 01 raptor 660. Open air box with flow pro filter,
pilot jets 25
main jets 165, 170
needles on 3rd clip.

starts good, idles great, runs great until I get to 5th gear in the upper rpm's on a open road, starts to stumble above 1/4 throtle and have to back off to keep it going. Like it's starving for fuel or too much fuel. I live in utah at 4500 altitude. Should I try adjusting the needles first or change the jets?
Too rich for that altitude....................
 

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Discussion Starter · #4 ·
thinking about getting the vito's jet kit off of ebay, if i rejet to 155, 160 should I put the new needles in that come with the kit? What setting?
 

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Master of the Electron
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Are you running stock needles currently? What mods to your airbox? Have you always been at 4500 feet?
 

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Discussion Starter · #6 ·
I'm guessing the needles are stock, got this bike third hand. Air box is just the bottom box with pro flow foam filter kit. Slip on Lexx exhaust. As far a altitude 4500 is where I live, we have mountains all around us so where I ride will range from 4500 on up to maybee 6000. The bike runs awesome until I get in that upper rpm range in 5th gear I cant go above 3/4 throttle, it starts to stumble. So I'm thinking of leaving the needles where they're at and just jetting down a step. What do you think. Spark plug is blackish in color.
 

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I am unique
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22,621 Posts
I'm guessing the needles are stock, got this bike third hand. Air box is just the bottom box with pro flow foam filter kit. Slip on Lexx exhaust. As far a altitude 4500 is where I live, we have mountains all around us so where I ride will range from 4500 on up to maybee 6000. The bike runs awesome until I get in that upper rpm range in 5th gear I cant go above 3/4 throttle, it starts to stumble. So I'm thinking of leaving the needles where they're at and just jetting down a step. What do you think. Spark plug is blackish in color.
Drop the needles a notch and reduce the mains one size....
 

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Master of the Electron
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Willy has the right idea!
 
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