Model: 2002 YZ426f Timing: YZ Main Jet: 165 Pilot Jet:42 Starter Jet: stock? Leak: #58 installed (MOD) Fuel screw: 1/2 -3/4 turns out Needle:Yamaha NDJQ at #4 clip (1 needle leaner than stock "P") Air box: no lid, K&N ( I hate cleaning the foam filters) Pipe/muffler: DRD 3.5 X 14 w pipe & quiet core insert Altitude: 1300 feet Temp:current 80-100F Humidity: 70% Other: BK mod sub 1 second squirt, #58 leak jet, Boysen AP cover Degree of satisfaction; Runs well. I worked a long time to beat a bog and have it reduced. The bike gives conflicting signals (ex. Fuel screw in all the way increases RPM but runs better under load with this pilot). If I go up on the pilot/fuel screw =slight rich bog on the AP, if I go down= slight flat spot in the middle of the RPM range but good snap higher and lower. The 42 pilot gives the best loaded performance. Tunable BK mod bolt helps a lot. I like the leak jet as well. I can tune across more tempreture range.