81 KZ305 hard starting

wrote:

They are Keihin carburetors. I don't know model or size. 
 

CV-32

Are you running brand new gas?
The gasoline formulation is different for winter.
Winter gas allows easier starting cold weather(you may not have any difference between winter and summer gas in Virginia).
Plus, if you let gas sit, all the good stuff that helps with starting can evaporate.
Especially if your tank isn't completely sealed which most tanks aren't on vintage bikes.

Also are you running 20w50 oil weight?
20w50 can make starting a bit difficult in the winter.

credit: car and driver
www.caranddriver.com/news/a15339380/the-...-gasoline-explained/

I ended up putting a small screw in the choke plate flappers. The bike now starts with the first crank of the engine using 90% choke. If I use full choke the engine will not start, but it's not a problem limiting choke to 90%. 
I'm guessing the flapper springs lost strength over time.