Quote:
Originally Posted by David v
Hi there!
I?m just curious... I fitted a NEDJ needle instead of the standard N1EF in my AS2 in the 2011 Gas Gas EC300, and by eye, I could not tell the two apart. Measuring the diameter in every 5:th mm along the length gave this result in millimeters, starting at the thick part:
N1EF NEDJ Difference
2.70 2.74 0,04
2.69 2.73 0,04
2.69 2.73 0,04
2.64 2.65 0,01
2.55 2.57 0,02
2.41 2.43 0,02
2.28 2.29 0,01
2.07 2.10 0,03
1.79 1.85 0,06
1.53 1.57 0,04
At idle or very small throttle openings the difference is only 0.04 mm and that is a pretty darn small difference! Does anyone know the diameter of the hole that the needel sticks in to? It would be interesting to calulate the area difference.
Cheers!
/David
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The hole is about 2,91 +-0.2 due to my own measurement with test pin.
First of all:
Thanks a lot! This really prevents me from buying Suzuki needles NEDJ NEDW and so on. They all vary only in base diameter, tapered sections are fixed for those needles.
As you have shown, the tapered sections dont differ significantly. In the tapered section 1clip up or down changes Diameter more.
BUT:
The Base diameter of NEDJ is four sizes leaner than N1EF and equals N1EI (2,735) or N1EJ (2,745)..
To decide whether 0,04mm is signifcant, always consider the area of interest is the space between needle and bore:
Next question, do 0,04mm matter?
Yes and no!
0.04mm at Base diameter is very significant, as the Area for the premix Air/Fuel flow between Needle and the Bore is what matters. This is 2.9mm bore minus 2,74 vs. 2,70 Needle. Here Differences has to be calculated by Difference of Areas=Diameter^2*PI/4:
Result Difference 2,7 and 2,74 equals ~24%.
At the needle tip the same 0.04mm have far less effect. The same calculation leads to a difference of ~2% in the open flow area (1,57 vs. 1,53)
This is the reason all Needles are seemingly very similar at the start Diameter, but differ a lot in the tip. To change the flow at the needle tip significantly you need large diameter variation. For changes at the base it is much more sensitive.
Best regards,
Erhard