Welcome. Start a thread in SOHC Bikes or Projects to get your troubleshooting done. You'll get far more eyes and ears assisting you there.
When you post, provide your model and year in the title as this helps a great deal.for instance, your title could be: '77 550 starting woes after rebuild
A bit Erie entail on your starting problem would help too. Does it crank, but not fire? Does it seem like it's not getting fuel, or weak spark? Is it backfiring while starting?
When you describe your problem, be as detailed as possible about the exact setup of your bike: coils stock? Which spark plugs? Points condensers new? Points gap checked? Carbs fully cleaned and floats set? What jets? Stock air box? Stock exhaust?
You'll get tons of questions if you don't list these details because people will want to help, but need more info to help you accurately.
So gather up your answers to these questions, open your new thread, and let's get your bike running!