Join Date: Nov 2009
Location: Lander, Wyoming
Correct, the brass spacer makes the top of the needle the same thickness as the non-adjustable button head of the stock needle, so the plastic retainer prevents the needle from sliding Up as the slide descends during deceleration.
#40 pilot should be the standard carburetor jet. That is what helps retain your lower speed fuel economy in town & on slower back roads.
If you do install the EM suggested #42 pilot jet, which many people do, to lessen aftermarket muffler induced 'after-fire' popping out the tail pipe, you should probably not use a shim under the needle circlip.
Like I said, it can be trial, error & experimentation.
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting