For whatever it is worth I fought the "Bucks and Kicks" for years. Changing
all the usual parts and tweaking all the usual tweaks brought zero relief
and it seemed like bucking and kicking was simply something I would have to
live with. Last year I made a routine replacement of my worn out muffler.
There has not been even so much as a hint of bucking or kicking since.
     I have no idea what connection, if any, the mufflers have with B&K and
the fix may be pure coincidence but there it is. All previous efforts had no
effect. I changed the muffler and all is smooth.
   If it is tear-the-hair-out time and you are out of ideas here is
something else to take a look at.