You can use spray degreaser (non foaming type) or even water dispersing spray like WD 40, but only through the plug hole. The good thing about that is you get the chance to check the spark plug as well as clear the cylinder of any excess fuel.
When my Ryan 31cc engined Ryobi weed wacker sat idle for too long, it just wouldn't so much as murmur. Start Ya Bastard got things back to normal and saved me an unnecessary carburettor kit.
