please read the discription on there website.  pretty certain it says its a lubricant.

http://wd40.com/products/smart-straw/

wd40 does not clean a carb well, not compared to dedicated carb cleaner.  a gallon can of carb cleaner is the best way so you can soak the carb.

cleaning a carb should be done on a bench on a rag so you don't loose anything.  doesn't help to drop the jets in the dirt if your trying to clean them.