Lately my bike is sputtering in the lower RPM's when I'm riding. If I twist the throttle the enging revs smooth and has good power. I just did the BK Mod but that didn't change anything good or bad. In fact the bike never really had much bog anyway. Could this be jetting related? I ride in the North Texas area and it's hot now. My bike doesn't do this when it's cooler. Any ideas?