Jetting a bike is a personel setup thing as much as being right or wrong. I hate a super crisp MX type zing for woods use. It won't pull good a gear high under a load and will spin bad in the proper gear. You have to jet a 125 this way but not a 300.
If the bike is to zingy then try moving the needle clip down at least 1 but maybe 2 clips. Adjust the air screw as needed. I want all rpms to have a TINY sputter at a steady throttle under a load. If it surges it's lean. You should have different needles. Try one with a smaller base diameter. Look up the codes or measure the straight section before the taper with a mic. This will richen up just off of idle to 1/8 throttle mostly. The carb is the most important. Do it before bothering with the PV.
I played with all of the PV springs and settled on red. Yellow or green just took bottom away then when the pipe came on you had a hit. Many will argue this but there was a very good set of dyno runs on KTM Talk that showed the same. The red spring with good jetting was super smooth while the other had a quick surge when the PV opened. Do play with the PV screw. It won't hurt anything and you'll find the sweet spot. Try it all the way out(Maybe 1-1//2 turn past flush) then 3-3 1/2 turns in from there to see the extremes then you'll see what doesn't work.
Be patient and take notes. It is worth the effort to learn. You will love the bike once sorted and will be able to adjust for any weather condition
LILBIT screwed with this post 01-23-2010 at 05:44 AM