The KF design, more so than any other RTA, works successfully due to two specific features... those being a
pressure differential, which is common among sealed tank type atomizers... and more unique to the KF design, a boundary layer (or level) that keeps the juice in the tank, until you produce a negative pressure signal.
Unlike most other RTAs, the wicks do not lay soaking in a juice pool... being fed as much by capillary action as pressure variances.
When not in use, you have two opposing pressures in a KF - the atmospheric pressure all around us, and
above the juice channels in the atomization chamber or chimney assembly - and then the opposing force, the negative pressure in the juice tank, or
below the juice (actually, when the tank is upright,
also above the juice), holding it in a relatively neutral position called the boundary layer.
The two pressures, combined with the specific juice channel orifice dimensions, hold the juice level in a stable position within those channels. Juice is metered out only when there's a sufficient increase in exterior vacuum (via the draw) to overcome the interior vacuum.
The boundary layer shifts upwards to the wicks. If this clever design balance is modified in any way... your fail choices become flooding or dry hits.
To reiterate the comments of DoubleEwe in a slightly different way... by enlarging the inlet air pathways, you've reallocated a larger percentage of your available draw vacuum towards drawing in fresh atmospheric air, and less towards lifting juice up the channels... and to the waiting wicks.
So you (or rather the folks who drilled it for you) selected dry hits as the modification fail.
commie said:
Every now and then I end up having to cover the airhole and take a few sharp dry pulls to feed it.
And that's what you'll be required to do from now on, unless you're willing to decrease the outside airflow back to the original capabilities.
