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i have a 2008 raptor 350. i have a stock exhaust that is gutted and a slip on k&n high flow air filter. right now i have stock jetting and i am having a problem with a low end miss. it is only missing until about half throttle, then it runs fine. do i need to change the jets? if so, which jet do i change?
 

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What do u mean a gutted exhaust?
 

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i have a 2008 raptor 350. i have a stock exhaust that is gutted and a slip on k&n high flow air filter. right now i have stock jetting and i am having a problem with a low end miss. it is only missing until about half throttle, then it runs fine. do i need to change the jets? if so, which jet do i change?
Try raising the needle one click so that the throttle opens faster.

You can usually increase you main jet 2 or 3 sizes with a high-flow intake over stock. When you rejet, start with the needle at it's lowest setting.

Also, you may need to adjust the mixture screw as you are leaner now.

Dynojet makes a jet and needle kit for the 350 Raptor that includes all the jets for intake and exhaust changes. (No affiliation, just a satisfied customer.)

YAMAHA 04-12 350 RAPTOR Q423 $59.43

Installation PDF: http://www.dynojet.com/pdf/Q423.pdf

There needle and seat (jets) are redesigned vs stock and will improve performance over the entire range. Very smooth too.
 

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The 2008 Raptor doesn't have an adjustable needle, that was only 05-06. Bump your main to like a 152.5 and your pilot to around a 25
 

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For just a stock exhaust and baffle removed with just a High flow filter just up your piolet jet to 25 no need to up the main your going to run too rich...install a new spark plug take it for a ride inspect your plug tip if it black=rich, white=lean, tan/copperish=perfection! 25piolet and 152.5main isn't a universal setup for every rappy350 out there...just buy extra spark plugs test and tune.
 

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Oh, I thought he said a slip on as in a pipe, yeah, you shouldn't need to up your main, if anything don't go past 147.5
 

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i have a 2008 raptor 350. i have a stock exhaust that is gutted and a slip on k&n high flow air filter. right now i have stock jetting and i am having a problem with a low end miss. it is only missing until about half throttle, then it runs fine. do i need to change the jets? if so, which jet do i change?
How's it run, now?
 

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i got the same set up but a 05, run a 25 pilot and either a 145 or 147.5 main, buy oem jets dyno jets numbers and sizes are different. mikuni, or keihin
 
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