Here is what typically can happen... or does happen
The fuels used these days are low specific gravity. Not very dense. After riding a while and then parking your bike, the fuel in the carb will percolate, boil out. Usually after 10 or 15 mins of sitting. The heat from the engine will transfer to the cooler carb known as heat transfer. This will boil the fuel out of the carb. The boiling temp of these new fuels is really really low. Not the best for carbs. Ok for Fuel Injection which is the push now days. At any rate, since your fuel has boiled and evaporated, a lot of it anyway, and now your carb is also so hot that any new fuel coming in the next time you try to start it will also boil away pretty quick until the carb finally cools enough from new fuel and air coming to make it so. Then.. It begins to start,..and then run.. and then back to normal after a min or two of running time. It is that 10 or 15min window that is the worst for restarts. There is not a whole lot you can do about it. some engines are worse than others with this problem. Some days typically hotter days are worse.. Intrinsic. You can try adding a thicker gasket between the carb and engine. That is about all you can do. Try moving up to a higher octane more dense fuel. that too can help. That is about it. Enjoy the ride..
