I have a '98 XR600R. It has been running fine until a recent ride when I started getting acceleration problems. When riding at lower RPM's and you want to quickly accelerate (3/4 to full throttle) the bike has a large hesitation. It is also noticed when the bike is idling and you snap the throttle wide open it also hesitates(it will sometimes stall when you do this). If accelerating by slowly rolling the throttle open there seems to be no notice of the problem. Today I have removed the fuel petcock and cleaned it. I also removed the float bowl on the carb, pulled the jets and cleaned them with carb cleaner. I also removed the air cutoff valve to inspect it and it looks fine. These procedures have not helped at all. I am now wondering if it could be an igintion problem? Anyone else had a similiar problem. I would really, really appreciate the help. The weather has cleared and I still cannot RIDE!!!