Hi I also bought a 1976 550f recently, running but not great, after some minor modifications in the spark plug wires and one carb that wasn´t running now is it´s a wonderful stylish bike to be on the road with. I use it for short trips, under 20 miles. It´s quite a conversation piece whenever we stop, my daughter generally rides with me. I´m not a mechanic but am somewhat mechanical so hopefully I can help or understand what i´m reading in here.