THe crankcase breather hose on k bikes cracks easy. I noticed a small crack about a month ago threw some tape on it and ordered a new one from beemerboneyard. The bike ran like it always had (low gas mileage at high revs, slow pick up, bad idle) up until I received the package, I replaced it and it only took me 5 minutes and now my bike is like new. Its hard to describe how smooth everything feels now, I don't have to keep the idle enricher on for two miles, Ive been on the same tank of gas for more than a week now and the red light still hasn't come on, and driving at high speeds and shifting up feels solid and quick.
Everyone should check this hose and make sure there are no cracks anywhere, if you see a bit of grime around it, odds are its cracked. However lucky for you that means when you replace the 15 dollar item you're bike will drive better than it ever has.
Just some info,
cheers