Lightly seated?

Ok, what exactly does lightly seated mean in re: to the pilot screws? I
may have discovered part of my problem......

I took my carb to a friend, and when we removed the screws, the rubber
o-rings were flattened. I am assuming "lightly seated" now means when I
am turning the screw in, and it makes contact with the o-ring, and NOT
bottoming out the screw, then backing out the screw the requisite number
of turns from there. If this is true, that means I was actually
starting from -4 turns, turning out 2.75, and my starting point for
tuning was actually -1.25 turns.

next question: my jets for the main are listed in the book at 115, but
the jet on one side ( and i haven't checked the other, yet) is a 118.
will that make a huge difference? i am going to pull the whole thing
apart later today to make sure numbers are at least the same on both sides.

 

No! Lightly seated means that the tip of the screw makes light
contact with the metal seat. The O-ring is only there to stop
fuel dribbling all over the place and has nothing to do with
the fuel or air flow.

 

so i am correct in "all the way in, then back out the requisite turns"
approach......

 

No, it is not a huge difference. You must have Keihin carbs because the
next size above 115 in a Mikuni main jet is 117.5...

115, 117.5, and 118 are diameters in percentage of a millimeter. A #100
round main jet has a hole that is 100% of a millimeter in diameter...

A #100 round main jet has a hole in it that is 0.0394 inches in
diameter...

A #115 round main jet has a hole in it that is 0.04531 inches in
diameter...

A #118 round main jet has a hole in it that is 0.046492 inches in
diameter...

So, the difference in the hole sizes is 0.00182 inches, in other words,
the #118 main jet has a hole that is only a tiny bit over a thousandth
of an inch
larger than the #115 main jet...

 

No, it is not a huge difference. You must have Keihin carbs because the

you are correct, sir, I do have Keihin. I just got thru cleaning them,
again. Maybe more thoroughly this time, I hope. I also made sure the
floats were even and approximately 7.5 mm above the rim. I am going to
sync the carbs tomorrow, b/c it appears the butterflies don't line up
evenly compared to the transition ports.

I do have one other about the transition ports. There are four in a
diamond shape, with the sides slightly offset from horizontal. The book
states the butterfly should be even with the small hole, and emphasizes
this. However, the pic looks like it only shows one hole, not four.
Can you advise?