That is interesting ...... good catch. I just looked at the part numbers at Partzilla and it looks like for the earlier year ST1100, the needles are different part numbers, but for the latter models they are the same ( ??? ). And for my '98 model, only the PN for the one side is listed, the PN for the other side is missing.
My needles are the samePrinted on the needles are the following
CARB NEEDLES #1 AND #3 J18P
#2 AND #4 J18Q. At least on my carbs.
Yes the interpretation I think should be left side and right side not front and rear. My RHS needles have a differ part number to you though. Detials:My needles are the same
2 x J1BP
2 x J1BQ
The Official part numbers for my bike (2000 ST1100AY - Police)
16131-MAJ-R00 (Front or Left Pair)
&
16191-MAJ-R00 (Rear or Right Pair)
Whats interesting though is that I interpreted the parts fiche as showing a front vs rear difference, now that I looked again I can see that it may be a left vs right difference.
I foolishly let my needles get mixed up when they went for cleaning, you mention #1/3 = J18P & 2/4 = J18Q , was this from observation i.e. when you pulled them from the carb bodies
Was wondering if you ever got an official answer on this one ? My query to Honda Japan got lost in the post , I aim to pick it up again soon once the local dealer gets back to more normal functioning. Its now going to be a long while before I need to deal with this again but figured I should try and find out the official answer before I do !Update: think the carb needles are paired front and rear. The two thinner needles on the back, thicker on the front. Thinner needles would make for a richer mixture and so cool cylinders on the rear and front ones would be cooled by air flow more than rear ones. This I suppose would mean even cooling on all cylinders. Your opnions please!!
With a liquid-cooled engine, cylinder position should make little difference in temperature-caused mixture need differences. You could also say that the front cylinders are nearer the radiator.Update: think the carb needles are paired front and rear. The two thinner needles on the back, thicker on the front. Thinner needles would make for a richer mixture and so cool cylinders on the rear and front ones would be cooled by air flow more than rear ones. This I suppose would mean even cooling on all cylinders. Your opnions please!!
Nope I didnt still a bit puzzled.Was wondering if you ever got an official answer on this one ? My query to Honda Japan got lost in the post , I aim to pick it up again soon once the local dealer gets back to more normal functioning. Its now going to be a long while before I need to deal with this again but figured I should try and find out the official answer before I do !
I have rebuilt several Honda 4's...both inline and V configuration. All the needles were identical.With a liquid-cooled engine, cylinder position should make little difference in temperature-caused mixture need differences. You could also say that the front cylinders are nearer the radiator.
My guess is the position of the jets within the bodies of the carbs are the same within each carb, and thus different for each side of the bike, to compensate for acceleration-caused fuel slosh.