Learnt something about my jet ski. The last two times out has been cold water (mid 40s and air in the mid 60s). I developed a real bad hesitation when letting off and reapplying throttle. I thought I might have to rebuild carbs and fuel pump. I richened up high and low speed screws 1/8 of a turn. That fixed it. It was great today (43F air and water). I might have been a little lean all along. I switched from 60:1 to 43:1 and the carbs still had there stock settings. Summer was fine.