White / grey indicates overrich, no wear inside to be afraid of (yet).
Most likely causes in descending order of probability (IMHO, of course):
1. Choke plunger sticks, blipping throttle makes it close or something. Closed choke does not mean necessarily that it isn't operating. Push back choke plunger at carburettor. If that does not help, remove choke plunger and check for smooth operation. Alos, check cable.
2. Float problem. Dirt / worn needle / needs adjustment.
3. Second stage throttle slide sticks in open position. Clean, preferably replace.
4. (very) Dirty air filter. Clean.
2 and 3 need carburettor dismantling. First check 1 and 4, takes 10 minutes.
Excessively overrich mixtures wash away the lube oil film from the cilinder wall and so may cause damage when not cured, just to make you sleep well tonight.