spray the carb cleaner when the engine is cold . "the first start up of the day". this is when you most likely will find any vacuume leeks, and less risk of fire. you can use just about any type of spray. even a watter bottle.

by spraying a liquid around the carb and intake if there is a vacuume leek . the liquid will be sucked into the leek and temporary blocking the leek. you will notice a slite to moderate rise in engine rpm and the engine may run smooth for a sec. do this several times and wait between attemps to really make sure you have located the leek.

I used my standard paint program to draw on the pic and uploaded it in a jpeg format. no problem