remove the air box lid....remove the air cleaner

start the engine ( it will run like crap.but should still run)
look down into the carbs with it running, both carb slides should be
pulsating at the same rate.
if that's ok...
pull the pilots jets out of both carbs and clean
if you don't know where the pilot jets are,watch this vid if that doesn't cure it ..adjust the valves
I've had similar problems in the past with these kawie v-twins..good luck

 

Front slide pulsating,rear stays still until reving up or popping.Not popping through front carb.

 

sounds like front cylinder not running or hitting....should be still until revved up.

 

Was just told by vbalz they both should be pulsating.
Back carb popping back,front carb. running ok.

 

have a 650 with the same carb problem - does anyone know someone in this area ( zip 28663) Piney Creek NC - who can fix the carbs for us. had a small engine guy work on them and sounds like one screw wasnt replaced or fell out on the way home - but may need new carb