Re: How do you detect air leaks?
If it has an air leak and you run it too much, you will kill it.
If you mean when spraying, sometimes you'll barely hear it speed up or slow down.
Just fire it up, have a helper hold the clutch in and spray around the places like the carb to manifold joint, manifold to cylinder gasket. It's easier to just take off the manifold where the two bolts hold it on, smear a thin film of RTV or any other silicone on BOTH sides of the gasket, and re-install.
You may want to check the top of the carb too. sometimes they are loose and suck air in there too.