GYTR needle

I was jetting my 08 WR 450 after I installed a FMF 4.1 exhaust (168 main, 48 pilot, 50 leak) and use the needle I got with my AIS removel kit. It sputtered and cut out at about 1/8 through 1/2 throttle. So I ajusted the clip a couple times and it still did it. I removed that needle and put the stock needle back in and it seemed to fix the problem. I was told that the needle with the AIS kit is the same as the YZ needle. Is this true. If not then I want to get a YZ needle because I heard that that will help. I just want to get the most out of my bike.

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What is your elevation?

I was jetting my 08 WR 450 after I installed a FMF 4.1 exhaust (168 main, 48 pilot, 50 leak) and use the needle I got with my AIS removel kit. It sputtered and cut out at about 1/8 through 1/2 throttle. So I ajusted the clip a couple times and it still did it. I removed that needle and put the stock needle back in and it seemed to fix the problem. I was told that the needle with the AIS kit is the same as the YZ needle. Is this true. If not then I want to get a YZ needle because I heard that that will help. I just want to get the most out of my bike.

did you start with the middle clip position?

my elevation is 5000 feet and I started the clip on the 4th notch down then went to the 5th then went to the 3rd.

I removed that needle and put the stock needle back in and it seemed to fix the problem.

The needle taper of the AIS/YZ needle must be too rich for your elevation. The taper of the stock needle is really lean (i.e no taper at all). Thats probably why you could get away with running the 168 up there with the stock needle. Do you ride places with alot of elevation changes? Some places I ride can change as much as 2000 ft from the staging area all the way to the top...so if you're starting at 5000ft its possible you could be up to 7000ft or more at some points in your ride.

If you are getting up to 7000 ft the 168 main is too rich IMO...even w/ a wide open pipe. The 165 with the AIS needle in the 3rd or 4th position would be good I would think.

Thanks for the info. I will try that.

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