High speed bog could be a lean condition if it pops or backfires when you shut the throttle. The needle position helps the transition from pilot jet, through the midrange and into the main jet running. Think of this, the pilot is a small hose that runs constantly, the needle is a pistol grip hose nozzle that goes from nothing to wide open, or main jet. Both the pilot and the main jet contribute to the overall WFO throttle. The air/fuel ratio needs of the motor change during the run up the revs. The needle is used smooth this out.

main jet sizes are all over the place because everyone uses a different diameter needle and taper. Look at a stock needle and it is very thick and tapers quickly at the end for smog certification. Jet kits always use a thinner needle to lessen any restriction in the air passage of the carbs, and that's why some of them use smaller mains.

The black crud on the pilot screw could be crud that accumulated when it sat.

Side note: do you have the rubber barrier that covers the area in front of and below the airbox? If not, it is known to cause high speed fueling problems.

 

Thanks for all the info. The info I found is that when I put the 145' and 140's in along with a K and N and aftermarket exhaust, the pilot screw should be 2 turns out. Hows that sound? They were 2.5 when I took them out

 

theres no exact number of turns that they should be out for certain mods. there is a whole tuning procedure you have to go through for the pilot screws, and its a real PITA

 

I just want the bike to run right. SO what do you suggest?

 

get a jet kit, get to a point where YOU think the bike is running pretty well, put it on a dyno with an exhaust sniffer(the sniffer measure air:fuel ratio), and that will show you if youre running rich/lean, and where at in the rpms that you are running rich/lean. If its running rich/lean in the higher rpms, its your main jet, if its in the midrange, its your needle height, if its down low, its your pilot jet and/or pilot screw.

if you get a dynojet jet kit, it has a pamphlet in it that will suggest what jets to start with, doesnt mean that it will be the best jet, its just a starting point.

i know what youre going through, and yes it is frustrating. ive been doing the same all summer. got mine running really sweet, then i found out i had a bad coil. messed everything up and i had to start over again. Just stay patient and do some research so when youre out riding you can tell what needs adjusted/changed.