needle jets

[mack]

Just a quick question. My LH manual calls for 16's, and the spare set of carbs came with 18's. The needle profiles look the same to me, the only difference I can see is the 18's have multiple c-clip positions. For tuning purposes, would there be any difference between them if I use the center c-clip slot.

[Rasputin]

I am not sure of the differences between those two numbers but my early and later carbs show a quite difference in the taper of the needles. I have the two of them in my hands (well I put em down to type) and the taper is much longer and comes to a finer point on the later carbs. Calipers really show the difference as well. Thes are stockers to the best of my knowledge, but after 30 years who knows what PO's have done.

[mack]

Thanx

for the response. I didn't check with calipers and my eyes aren't what they used to be. The thinner taper would make them run richer? I have three of the required four 16"s thanx to Crazy Steve sending me a bunch of his spare parts. I'm trying to figure out how to set the fourth so it will match. I haven't found a source for these yet. They don't show up on georges site either. It will be a bit before I have the bike ready to run. My back is getting better, but not quite there yet. I'll just put the offending needle in an outside carb and experiment with the c-clip positions.

[Lonerider62]

If your needles have different tapers, it will be almost impossible to get them to act the same, except maybe at WOT (if they are the same size at that throttle position. You could end up with a really lean condition in the cylinder that has a thicker needle. I don't think I've heard of anyone running different needles but I suppose if you knew a particular hole was running cooler or hotter, that could possibly offset that situation but it would take a lot of trial and error to get it right.

[SFerinTEXAS]

Curios where you are getting the 16 and 18 references to the needles. Never seen it that way before. What kind of manual are you using? The 78-9 use the adjustable clips and the later use the fixed clips.Do not know about the aftermarket styles. I believe you have them mixed up together and that will not work.

[mack]

References

I'm looking at the numbers on the needles themselves.(using very large magnifying glass) my reference is the large white amendment book. It has the corrections for the LH,SH, and the basic 78 E same as clymesr but with an amendment segment.

[Rasputin]

Well a guy learns something new every day on this site. I went out to the garage in search of a spare needle for you. I found a 51Z7 needle which has the single groove. When I looked it up it shows this as correct for a 81 standard but it does show a 5GL-16 for the special. Then I ventured into my 79SF specs and it shows a 5GZ6/3 needle which is also shown for the 78 and 79 standards. Apparently the later carbs have different needle jets between the standard and special models. I for one did not know that.
I do have a spare 51Z7 needle here if it would do you any good. In comparison to the 5GL-18's I have, it is a very slightly different taper and the overall length is 1.33mm's longer. I included that so you may compare that against the 5gl-18 and 5gl-16 needles you already have. I have two sets of the later carbs running now, but can not rob parts from them. All of the other needles I have are for the older carbs. Sorry, but that is all I can offer in way of help.

[mack]

No don't

cannibalize a set of carbs. I have one comming from someplace else and it should work. This is for a third bank of carbs I aquirred for the LH so it's not critical to getting "Spica" running again. But, I really appreciate the offer.