I just bought a used 2001 RMZ400E. It's my first 4 stroke dirt bike although I've owned several 2 strokes in the past. As far as I know it is all stock including the exhaust. I'm having an issue with the bike not wanting to come back down to idle right away when I'm riding. The bike is pretty cold blooded and has to be warmed up pretty good before it will take any throttle without the choke but once warmed up it idles fine and seems to make good power; however, pulling the choke on even when the engine is hot results in an increase in engine rpm. The problem comes in when I rev it up either in neutral or while riding. The bike wants to idle at about 1500-2000 rpm for a few seconds before it drops down to normal idle. I pulled the carb and checked the float level and low speed jets and they are all clean and clear. I blew air through the low speed jet and felt it blowing in the throat of the carb so I think the low speed passages are all clear. Because it is the "e" model, the starter blocks access to the idle mixture screw when the carb is on the bike so I cannot adjust the idle mixture with the bike running. The idle screw was 1.5 turns out when I took the carb off and it changed it to 3 turns out because I believe it's running lean at idle. It seems to have helped some but it's still not right. I'm thinking I need to go to a larger pilot jet but I'm looking for advice before I go down that path. Thanks in advance for any help or insight you might be able to offer.