It is always prudent to have the aircleaner installed as a flame arrestor.
Is it misting constantly, or spitting erratically?
Either way, manifold assemblies cannot always be trusted just because they are fresh. For certainty, please bubble-test as discussed at http://virtualindian.org/11techleaktest.html
. It may save you a tail-chase.
Constant misting can be one or more conditions, such as poor ring seal, or a faulty camchest breather valve.
A more common cause can be too high of a fluid level within the carburetor bowl.
This results if the float is too heavy, such as when logged with fuel, or hanging up upon the bowlstem or side of the bowl. The position of the bowl is as important as the offset of the float within the bowl; It should be rotated to where the valve is quite close to the choke mechanism.