YZ Needle


1 reply to this topic
  • 123BigcoopDawg576

Posted September 16, 2008 - 06:00 AM

#1

I have noticed that when it comes to buying the yz needle for the carb that there is about 10 different opions.

Can anyone tell me what this is all about and how do i go about figuring how each one is different in how they preform.

Thanks

13 SKU: 5TA-14916-LR-00
NEEDLE (#NFLR) STD STD 1 $9.76 Add to Cart
13 SKU: 5TA-14916-LN-00
NEEDLE (#NFLN) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-LP-00
NEEDLE (#NFLP) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-L1-00
NEEDLE (#NFLQ) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-LS-00
NEEDLE (#NFLS) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-LT-00
NEEDLE (#NFLT) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-LU-00
NEEDLE (#NFLU) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-PN-00
NEEDLE (#NFPN) AP AP 1 $10.38 Add to Cart
13 SKU: 5TA-14916-PP-00
NEEDLE (#NFPP) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-P1-00
NEEDLE (#NFPQ) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-PR-00
NEEDLE (#NFPR) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-PS-00
NEEDLE (#NFPS) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-PT-00
NEEDLE (#NFPT) AP AP 1 $9.76 Add to Cart
13 SKU: 5TA-14916-PU-00
NEEDLE (#NFPU) AP AP

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  • grayracer513

Posted September 16, 2008 - 06:36 AM

#2

Go to this site and download a manual for an '06 or '07 YZ450:

http://www.yamaha-mo...ice/manuals.jsp

On page 7-7, it goes into an explanation of how the needles differ. All NF** needles have the same taper. The 4th character of the code letters tells the diameter of the straight portion of the needle. The third character tells how far up or down the needle the taper starts.

The diameter of the upper straight portion of the needle begins to affect the mixture as the throttle is raised off idle, and is most significant between 1/8 and 1/4 throttle, after which its effect tapers off quickly, and the taper becomes more meaningful. This simply because at about 1/4 throttle, the straight portion is fully drawn up and out of the needle jet. The taper of the needle is the primary influence on mixture control between 1/4 to the area of 3/4-7/8 throttle, after which, it's all main jet. Changing the main jet influences part throttle performance somewhat, more so at higher throttle openings, because the fuel metered by the needle comes from the main.

The Standard YZ450 needle is the NFPR for an '06, and an NFLR for the '07. These two needles are identical except that the clip grooves in the NFLR are moved up half a step on the needle compared to the NFPR. This means that the NFLR with the clip in 4 is half a step leaner than an NFPR with the clip in 4. Not a great deal of difference.

When selecting a needle, be sure you get one for the correct year, as older carbs used a different taper, and it's probably safe to start with the standard needle. Also, it would be wise to poll those who have swapped a YZ needle into a WR and see what they ended up with.





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