Mine dies at 55 mph in 4th or 5th. gear. I suspect it is the rubber vacuum diaphrams in the carbs. Upon inspection, mine had rotted due to age of machine. I can see redline in the lower gears though. I have´nt gone to the Honda dealer yet so I really can´t say for sure. I´ve also checked for water in the fuel, which nowadays is like dog %!¤ anyway. Did´nt find any. ?????? anybody have any clues as what I need to check next? I don´t have a manual yet.