All 2st Needles digits and numbers

[Johnnymannen]

Does anyone know how to read the needles? For example: My WR 300 has a needle named 6GAY69-74. There is an optional one named 6DEY15-74. How do you read out the difference? Which needle is leaner or fatter at a specific throttle opening? Just curious to hear your theories or facts!

Johnny:sweden:

 

[MOTORHEAD]

I know this no help to you, but personally, I hate the Mikuni needle codes. It's hard to find good info on the break downs. My hat's off to those who have mastered it. If anybody has some sort of chart or insight into the Mik needles, I,d love to learn.

Me, I just like the performance and ease of jetting the Keihin much better.

 

[MattR]

When I was researching Yamaha YZ125 vs. Husky CR125, I came across this explaination. This will show the basics of the Mikuni needle code. It's definitely more confusing than the Keihin.

Example of Yamaha YZ125 Needle (6BFY42-74):
6 = Series 6 needle
BFY = Triple tapered: B / F / Y
1st taper = B (30sec = 0.5 deg)
2nd taper = F (1min 30sec = 1.5 deg)
3rd taper = Y (6min 15sec = 6.25 deg)
42 / 43 / 44 = Standard / 0.5 clip Richer / 1 clip Richer
-73 / -74 / -75 = Needle Straight Diameter (OD) = 2.73mm (1 step richer) / 2.74mm (standard) / 2.75mm (1 step leaner)

Example of the Husky CR125 Needle (6DJ8-60):
6 = Series 6 needle
DJ = Double tapered: D / J
1st taper = D (1 min = 1 deg)
2nd taper = J (2 min 30 sec = 2.5 deg)
-59 / -60 / -61 = 2.59mm (1 step richer) / 2.60mm (standard) / 2.61mm (1 step leaner)

The way Mikuni Needle numberings work is:

• The first number is the length series. Lets take the series 4 needle. It could be 40.00-49.99mm in length. In turn a 5 could be 50.00-59.99mm in length.
• The second and sometimes third characters being letters describe the taper from the clip end to the tip in 15 second (1/4th of a degree) increments. For example "B" is 30 seconds, and "E" is 1 degree, 15 seconds. Therefore a "BE" would be a taper starting out at 30 seconds (1/2 degree), followed by a second taper of 1min 15sec.
• The last digit be it one or two characters is the suffix or revision number. Example. 4D3, and 4D8 are the same style needle, similar in length and taper. However the taper may begin higher up on the needle than the other. This would make a smaller tip diameter, or a shorter needle. If shims, or clip positions were incorporated on one needle it is possible that it may effectively perform like the other. For this reason we sometimes suggest ordering a 4D3, or 4D8 for example if an OEM application calls for a 4D5 which is not available, instead of a 4E?
• The numbers following the "-" denote the Major OD and is read as follows. "-60" is equal to 2.60mm OD.
• One last note: A suffix number has the following unknown variables between one needle and another. Exact length, Major OD, Point of begining of taper in reference to clip position. Without physically measuring them there is no way to determine these characteristics just by looking at the part number.

 

[MattR]

Does anyone know how to read the needles? For example: My WR 300 has a needle named 6GAY69-74. There is an optional one named 6DEY15-74. How do you read out the difference? Which needle is leaner or fatter at a specific throttle opening? Just curious to hear your theories or facts!

Johnny:sweden:

6GAY69-74:
6 = Series 6 needle
GAY = Triple tapered: G / A / Y
1st taper = G (1 min 45 sec = 1.75 deg)
2nd taper = A (15 sec = 0.25 deg)
3rd taper = Y (6 min 15 sec = 6.25 deg)
69 = I'm not sure. See below
-74 = 2.74mm OD

6DEY15-74:
6 = Series 6 needle
DEY= Triple tapered: D / E / Y
1st taper = D (1 min = 1 deg)
2nd taper = E (1 min 15 sec = 1.25 deg)
3rd taper = Y (6 min 15 sec = 6.25 deg)
15 = I'm not sure. See below
-74 = 2.74mm OD

Note:
The 69 vs. 15 is difficult to decode because they could offer different clip positions. You almost have to set the 2 needles next to each other and compare lengths and clip positions.

Based on your two needle codes, it appears the primary difference is the 1st and 2nd tapers. Which should have an effect on the 1/4 to 3/4 throttle range.

 

[MOTORHEAD]

Good stuff MattR. That's the best I've seen.

 

[Johnnymannen]

YESSS! Grate info! Thanks! There is a big difference in the way the engine runs! JJ Hawk from Finland, who recommended the needle to me, who also is a Husky dealer and races a WR 300 says that this is the best needle for it to get a better low and middle engine respons. He felt that it was "dead in the middle" with the GAY needle in the sand. I tried the needle in second clip pos. yesterday with a 40 pilot,(45 with GAY needle) and the bike runs really soft and smooth on idle compared to the GAY needle. I t also runs very clean now as soon as a open up the throttle slightly. You could say that the engine feels very "kind" on light throttle compared to the GAY one. I can´t say that this engine is as strong on the bottom as a KTM 300, but as soon as you reach middle revs it goes! And very clean with this needle! But JJ has changed to a Keihin too, which he think is even better, and not so sensitive to jetting and gives better low and mid power...But i can recommend this needle to the Mikuni anyway. JJ thought it was from a CR 250

Johnny:ride:

 

[Rusty 2]

I'm just wondering how long it'll be before you can't stand it any more and slap a Keihin PWK on that WR300 Johnny.
You love to tinker with jetting, and you're thinking about it,....aren't you?

 

[Johnnymannen]

I'm just wondering how long it'll be before you can't stand it any more and slap a Keihin PWK on that WR300 Johnny.
You love to tinker with jetting, and you're thinking about it,....aren't you?

Why do you think that! yes, i´m intrested in the art of jetting, and when i get in to something i want to learn all i can! We´ll see what happens, but if it´s a straight over swap and it makes a big difference i´m not against to try the Keihin! Just want all the info i can get first. The parts in the U.S is much cheaper then here. For example, a skid plate here is about 150 dollars! I saw JD had the Keihin for 239 i think with their kit in it. Hmmm...

 

[Johnnymannen]

I'm just wondering how long it'll be before you can't stand it any more and slap a Keihin PWK on that WR300 Johnny.
You love to tinker with jetting, and you're thinking about it,....aren't you?

One thing just came to my mind:Maybe i could try my friends Keihin from his KTM 300 EXC!

 

[Rusty 2]

One thing just came to my mind:Maybe i could try my friends Keihin from his KTM 300 EXC!

Now there's a good idea! You could just,..........hey wait a minute,
are you talkin' about me or the cat you ice race with?!

 

[Johnnymannen]

Now there's a good idea! You could just,..........hey wait a minute,
are you talkin' about me or the cat you ice race with?!

Haha! Get out in your garage and release the carb and send it to Sweden! It´s not that far away! You shouldn´t be riding KTM anyway!

 

[Rusty 2]

Haha! Get out in your garage and release the carb and send it to Sweden! It´s not that far away! You shouldn´t be riding KTM anyway!

You ice blasting hooligan you,...........