SemiFast. You shouldn't have to screw with the idle screw, * cold engine or hot engine. Normally the engine needs choke to start when cold then can be 'feathered off' as the engine warms. 1) Sometimes a slight oil control problem will sort of compensate for the extra fuel a cold engine needs and start without choking.
I had similar problems with my 2004 Ninja 250 but it wasn't jetting. I hope a fuel additive solves your problem but if not I'm guessing you have some stubborn gunk blocking a passage. 1. Get a bucket of chemdip from walmart. Soak the carbs and metal parts for 24 hours. Remember to fully disassemble including jets, needle seat, and idle mix screws. Here's how. You need to run a clear tube from the bottom of your float bowl up the side of your carb body to see how much fuel is actually in there. My bike is a 1994 KX 250 with a Keihin PWK38, so the proper fuel level should be 0 - 1 mm above the float bowl mating surface. 2008 - 2012 Ninja 250R Tech Talk: 71: December 15th, 2017 03:38 AM: Question about adjust idle mixture screws: daverdfw: 2008 - 2012 Ninja 250R Tech Talk: 14: February 28th, 2016 05:34 PM: adjusting idle mixture screws: james250ninja: 1986 - 2007 Ninja 250R Tech Talk: 9: September 1st, 2014 10:29 AM: Idle Mixture Screw Problem: gogoKawi: 2008 A motorcycle can flood if you open the throttle while hitting the starter. A flooded carburetor can also be caused by leaving the petcock valve open, a worn or dirty needle and seat, an incorrect float level, or dropping your bike. A problem with the ignition system may also result in a flooded combustion chamber. z0ZgCK.