I'm new to carb stuff. I've been researching it for a few days now. I think I have a feel for it book wise. My question: What should I change from STOCK and sea level to 8000feet in the Sierra National Park, CA? I couldn't find a chart for this bike and particular carb. Some definitions I don't understand completely : Hard Breathing? Zingy? Poppy? Cutting out vs. Bogging out? Crackling vs. Shuttering/rattling? Yamaha WR400 year 2000 It has all stock settings: Model: FCR Keihin Main jet: 165 Pilot Jet: 42 Fuel screw (turns out): pilot screw 1-5/8 Needle/Clip position: 3rd Airbox lid (on or off): off Pipe: stock Altitude where you ride:sea level, but taking trip to Sierra National Park 8000 ft + Temperature where you ride: 75 degrees Are you happy with your current configuration: Its okay at sea level now, just cuts out at the first part of the throttle and back fires some when I let off of 3/4+ throttle. I just want it to be okay for the Forest when I go 8000+ feet - no fouling plugs or lame stuff. THANK YOU FOR THE HELP IN ADVANCE! The people in this forum are AMAZING!