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YZ250 & Keihin Needle codes

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Hey,

I posted this on AllThingMoto.com without much luck of help.

OK guys can you help me translate the Yamaha code?

I have a '98 YZ250 with the stock N3VF needle. I am all the way to the leanest clip and need a little more.

Here is what is available from Yamaha.

N3VE

N3VF--STOCK

N3VG

N3VH

N4AF

N4AG

N4AH

N4VF

N4VG

N4VH

I know that the last letter translates to the straight part of the diameter.

E= 2.645 mm or .1041"

F= 2.655 mm or .1045"

G= 2.665 mm or .1049"

H= 2.675 mm or .1053"

Anybody know what the First Letter, Second #, or Third Letter mean?

A stock Keihin needle reads 48-xxx= Taper first, L1 length second, Diameter in mm third.

Some OEM's read R xx xx x. First two=Taper, Second two= Diameter, Third=L1 length.

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Ive also been having a hard time finding info on the net.. Im gonna check out my manual, probably tomorrow, and figure some shiz out!! :)

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Hey,

I posted this on AllThingMoto.com without much luck of help.

OK guys can you help me translate the Yamaha code?

I have a '98 YZ250 with the stock N3VF needle. I am all the way to the leanest clip and need a little more.

Here is what is available from Yamaha.

N3VE

N3VF--STOCK

N3VG

N3VH

N4AF

N4AG

N4AH

N4VF

N4VG

N4VH

I know that the last letter translates to the straight part of the diameter.

E= 2.645 mm or .1041"

F= 2.655 mm or .1045"

G= 2.665 mm or .1049"

H= 2.675 mm or .1053"

Anybody know what the First Letter, Second #, or Third Letter mean?

A stock Keihin needle reads 48-xxx= Taper first, L1 length second, Diameter in mm third.

Some OEM's read R xx xx x. First two=Taper, Second two= Diameter, Third=L1 length.

Around these parts I am sure the "N" stands for "Not in stock" Does anyone have a dealer that stocks needles?

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Ya, I hear ya there. Finding a dealer that stocks even the common stuff is getting rare. If they cant find it in WPS or on the computer from the OEM's microfiche, dont even bother.

BTW, I ride from 4500'-9000' elevation if any one has a good recommendation.

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Ya, I hear ya there. Finding a dealer that stocks even the common stuff is getting rare. If they cant find it in WPS or on the computer from the OEM's microfiche, dont even bother.

BTW, I ride from 4500'-9000' elevation if any one has a good recommendation.

I run a lot from 2500-7500 feet.. When I ran my stock motor, these are the bolt ons with my jetting.. FMF Gnarly, FMF TCII, VF3 reeds and occasionally a 11 oz FWW.. I also run 1 gallon Trick 108 to 3 or 4 gallons of pump 93, mixed 40:1 Maxima Castor 927... I would run a 45 PJ, stock needle and clip, and a 175 main.. I know, especially up around 5000 ft, I was running too rich, but better safe than sorry!! :)

Probably doesnt help much :D

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Thanks. Last night I bought a Yamaha PDF manual for my bike. It had exactly what I was looking. It says the Third letter is your Taper starting position, Fourth letter is your diameter of straight portion and last number if stated is the clip position #. However it didnt state what the first letter or second # means.

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From James Dean:

"The factory 4 letter codes start with N, made from plated aluminum as described:

1st letter = N, and only identifies the needle as a hard plated aluminum

2nd and 3rd letters = Random codes from the factory for their identification of 2 or 3 tapers and the positions of these tapers on the needle based on the Keihin designer's drawing

4th letter = Needle straight diameter from a different table than 3 letter codes

I hope this helps.

Thanks,

James"

Translation: The 2nd and 3rd letters are basically randomly assigned codes that identify the drawings that detail the needle tapers and locations - no real way to translate the codes to actual needle parameters without the drawing.

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From James Dean:

"The factory 4 letter codes start with N, made from plated aluminum as described:

1st letter = N, and only identifies the needle as a hard plated aluminum

2nd and 3rd letters = Random codes from the factory for their identification of 2 or 3 tapers and the positions of these tapers on the needle based on the Keihin designer's drawing

4th letter = Needle straight diameter from a different table than 3 letter codes

I hope this helps.

Thanks,

James"

Translation: The 2nd and 3rd letters are basically randomly assigned codes that identify the drawings that detail the needle tapers and locations - no real way to translate the codes to actual needle parameters without the drawing.

Not that it matters but does the N then stand for nickle? Before this post I thought the needles were aluminum, havn't noticed any wear but would think over time it would happen. Maybe I should be looking at the brass needle jet for wear instead?

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From James Dean:

"The factory 4 letter codes start with N, made from plated aluminum as described:

1st letter = N, and only identifies the needle as a hard plated aluminum

2nd and 3rd letters = Random codes from the factory for their identification of 2 or 3 tapers and the positions of these tapers on the needle based on the Keihin designer's drawing

4th letter = Needle straight diameter from a different table than 3 letter codes

I hope this helps.

Thanks,

James"

Translation: The 2nd and 3rd letters are basically randomly assigned codes that identify the drawings that detail the needle tapers and locations - no real way to translate the codes to actual needle parameters without the drawing.

Thanks J.D.,

One more question.

If you stayed in the same diameter "F" would the starting position letter before follow suit, rich to lean(A to Q)?

N4AF

N3DF

N3VF

Thanks.

Hallsy-The needles are aluminum. They just have a hard coating on them. To me they look like a hard coat clear anodize.

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