I have an mc28 with the same items you listed above. It was way too rich. I got my hands on both hrc and jha needles plus the air jets. I've since sorted things out and it works perfect from 3k to 12.5k with not hesitation.

You can read what I've done in the members section. Keep in mind I'm on the coast in a highly humid area. So what works here may not work for you. I'm running really lean on the lower ends.


http://www.nsr250.net/forums/viewtopic.php?t=13124&highlight=