My 99 yz400 was running weird so I pulled the carb apart and found that the float valve on the valve assembly (what I would have normally refered to as a slide) was cracked. I bought a replacement ($136 + $8 for the gasket = &%$#@!?!?!) and reassembled everything. However, I have a question that I am having a very hard time finding an answer for so hope you guys can help...on the rod that holds assembly mechanism (fork) that lifts the valve, there is an adjusting screw and crown nut. I can't figure out what that adjusts or what the proper adjustment for that would be. Any ideas?? Thanks!!