Hi Gang, I am sooo new to this thing and I know so little it's embarrassing. Yesterday, I was prepping my new-to-me 2004 wr450 for my first ride tomorrow. I don't know what mods were done to it but am sure the throttle stop was done given the way this thing rips. When I first got the bike in January I was turning what I thought was the fuel screw to adjust the idle speed. Well yesterday it was b&^ch to start and when warm, the idle would fluctuate - high one minute, low the next. After doing a few searches I learned I am a noob and I discovered I wasn't turning the fuel screw but the black knob on the carb. The best picture is from ARin http://www.planetblade.com/arins/bike/jetting/8.jpg where I can now clearly see the fuel screw (red knob bottom of carb) and the black knob. OK, my questions, What the heck was I turning (one picture in the manual says is the throttle stop screw)??? Would it be responsible for it being hard to start and the fluctuating idle speed? And finally, where should this knob be set (open, closed)?