"Before installing the 169 series needle jet, the spray bar (shield) must be cut down or the mid range circuit will operate too late and screw up everything. With a pair of venier calipers set to 2mm, use the id measuring portion and mark off a line that is 2mm from the base of the needle that would be flush with the carb bore. Hold the needle jet in a vise (gently) and position the scribe mark in such a way as to use the sides of the jaws as a guide for the blade. Using just a fine (32 teeth per inch) hacksaw blade, cut just barely away from the line, leaving enough to trim the length with a fine file."
Years ago when I installed the Dave F mod I did not trim down the needle jet. I just found this information which wasn't part of the original instructions that I used. I haven't been running anything other than Dave F modded carbs, and have had tuning problems since I've owned the bike. I've gone through everything: timing, compression, new coils, leak down test, new batteries, etc..
I was thinking about buying brand new carbs, but figured I'd ask about this first.
All depends how modified the bike is, and have seen even the JL's run richer in the mid than Spec 2 pipes.
On my street ported setups.
I cut them 1.7mm or 2 mm off the top, not from the bottom.
Need more info on your setup...Engine modified?
RD350? RD400? Did you go with a Y boot? K&N or Uni? Are they over oiled?
Chuck
Thanks Chuck! I've been out of town and sorry for the late reply. I have a 73' RD350, over bored .025?? ( I haven't looked in a long time), 28mm carbs, stock manifolds, Y-boot and Uni, dyna S ignition (set at 2.0mm BTDC), pipeline expansion chambers.
I just cleaned and oiled my uni filter. I was pretty liberal with the uni filter oil spray can. Hopefully I didn't go overboard.