A stock 550 that ran yesterday starts on kick 1 to 3 tops, full choke. Then immediately drive off warming the motor, before any serious RPM is tried, with the choke at about 2/3 to 3/4. As you ride, bump the choke off in increments until it doesn't need it anymore and idles without a hand on the throttle.
The longer they sit the harder they start. After two weeks you can kick 20 times before it burbles to life one cylinder at a time. (I think it's precipitates stuck to the slow jet orifices.) But, if you give it 15-20 minutes of run time, it'll start tomorrow in 1-3 kicks.
The 550 has D7EA plugs which are hotter than the cold bastard D8EA found in other SOHC4s.
Clean plugs are important. Sooty ones siphon off spark energy needed to start combustion when cold. Also, cold batteries make less voltage (it's a chemical activity thing). Leaky points condensers make the spark worse. Higher resistance spark plugs boots make things worse.
Cheers,