OK before you spray anything....engine must be cold, rags around the base of the carb, safety glasses on (or squint) just kiddin'. Normally when a carb has sat for a long time with fuel in it, the fuel turns into a varnish like material. This varnish forms on any surface that the fuel is in contact with. As to where you need to spray the carb cleaner, that depends on the model/type of carb. The obvious places are; down the throat, the bowl/float area and any orifice that you can get the spray tube into from the can of cleaner. Be careful, some orifices are deadends and the carb spray will come back at you. If you have the manual for the carb you can follow the path of the fuel as it enters the carb. As far as "how much" use as needed to displace any "gra-doo" technical term. Then wait a few minutes for the cleaner to evaporate before starting the engine. You may get a few puffs of white smoke out of the exhaust on start-up, this is normal. Additioinally you can spray a small amount into the carb when it is running and manually feeding in some acceleration. This will clean deposits downstream of the carb. Too much will stall the engine. As for the techron, yes that is the one to use in the tank.
