BILL, DITTO PROBLEM I AM ALSO FACING WITH MY VF750F. I THINK THE AIR SCREW SETTINGS FOR ALL 4 CARBS SHOULD BE TIGHTENED HALF A THREAD, MOREOVER, WHEN HOT, THE SPARK PLUGS MAY NOT BE RESPONDING AT HIGH TEMPERATURE, TRY USING THE OEM SPARK PLUGS. AIR SCREW SETTINGS SHOULD BE DONE ON TRIAL AND ERROR METHOD, UNTIL IT STARTS AT HOT ENGINE.