From My Experience. (I've pretty much done nothing but work on motors all my life. In 1952 at 8 yo I was flying 1/2 A control line model airplanes with those little Cox .049 motors. If you could make those little things run you can probably make any thing run. Read every word of every Rod and Custom and HotRod magazine.
First car was a "49 Ford flathead V8. Put 3 Stromberg 97s on it with scavenger pipes. Thought I was cool. Had a "53 Belair Convertable. "59 Belair Hard Top, "65 GTO and a "68 Dodge Charger R/T 440 Magnum 375 HP. USAF Missle Electronics Guidance and Control Technician. Not quite rocket science, but pretty close. Opened my auto repair shop in "72 and averaged more than 2 major overhauls a week from "72 to "90, mostly air cooled VWs. Built a 440 for my 360 Dodge Maxi Van, Put a turbo on a VW Bus, built a motor for a Formula V race car, built a 4 carb Corvair for a Porsche 912, built buggy motors with two 2 barrel Webers (Webers are great) and Delortos. In "91/"92 ran a Cat 963 Track Loader at McMurdo Station in Antarctica. Closed my shop in "95 and went to work for a rental equipment co/ John Deere Dealer untill I retired. Finished 10th in the Texas State Enduro Circuit(250 class) in "74. Finished 9th in the Texas State Trials Championship Master Class in "76. Rides in Colorado, Mexico, New Mexico, Arkansas, Contintal Divide Trail and ~ 1/3 of the TAT.) Sorry for the long winded list of credits,got carried away and memory lane is just fun.
Again, From My Experience. When you walk up on an cold bike that's been sitting for a few days or months, more than likely it's in a lean condition. It's probably not gonna start like that. Now, you can either apply the choke and kick/crank from that lean condition untill you get it rich enough to start or some how add enough fuel ( pumper squirt or pour some gas down the carb throat/remove the plug and add fuel) to make it a little rich and open the throttle to add air and kick/crank untill it gets lean enough to start. Down in Antarctica when it was 60 below zero and the big diesels wouldn't start we would soak a shop towel with gas and wrap it around the air filter. Knocked like hell, but it got em started. I don't recommend doing that. I'm sure you have had trouble starting your weed eater or mower after it has been sitting all winter, Dump the old gas, add fresh gas, pull the plug and put a LITTLE gas in the plug hole, open the throttle all the way and crank. It may only run a few seconds untill the prime is gone, but then it's in the right air/fuel condition to start. Works good for bikes too. Of course all of this assumes the rest of the motor is in good operating condition. BIG ASSUMPTION. So you guys with the e-start or pumper carbs have a little advantage (as long as you don't flood them) when it comes to starting. The kick start models with the CV carbs are gonna be the harder to start. That's why Greg says he kicks his through several times to prime it before he trys to start it. But then the guys with the CV carbs are gonna get better gas mileage and better altitude compensation. There are always trade offs. Hope this helps.