The only reason a bash plate is fitted is to protect the bottom of the frame and more importantly the lower extremeties of the engine itself from catastrophic contact with solid objects such as rocks, logs etc

Those who have actually hit solid objects at any pace will testify to sickening sound it makes, and immediatley thank their lucky stars that they had the foresight to fit a decent bash plate, in place of the plastic item supplied by Yamaha.

I assume we all agree that bash plates are essential items to have fitted if we intend using the bike for its "intended" purpose and not just there for show although the plastic bashplate hardly qualifies. There is however, a downside to this....they do limit the amount of airflow around the sump area of the engine. In certain circumstance and particularly in torturous riding conditions, this may result in higher thermal loads being placed on the engine, as the oil, is not able to carry the heat away from the internal running components effectively....(Oil is not only for lubrication, it also serves as a cooling medium.)

Drilling holes strategically in a bashplate is not as silly as it sounds, but it may in fact cause other problems, such as allowing mud etc to build up on the bottom of the engine and may actually reduce the strength of the bashplate itself. How carried away you intend to get with the size and number of holes, would have a lot to do with the expected riding conditions mixed in with a degree of common sense .

If you take a look at some of the bashplates available for adventure and enduro bike you will find that manufacturers that have access to laser cutting facilities tend to provide holes and slots to promote airflow

The object of the exercise is to enhance airflow yet still maximise protection....