The 11 tooth sprocket should come with a circlip which snaps into the groove on the shaft after you fit the sprocket.
To start my TYS I use full choke and very importantly NO THROTTLE, put your hand on the handlebar beside the throttle to avoid twisting. It always starts on the third kick.
As soon as it starts reduce choke to 1/2 and then very gently begin to apply throttle as the TYS does take a bit of coaxing when cold.
Whenever it is warm one kick is all it ever needs.
I would suggest touching no carb settings until run in and then fit the pilot and main jets and airbox mods as recommended by the distributors. This should further improve starting.
Regards
Rab