Super jet pump question

Hi guys, I wanted to ask if anyone can help me understand why on one of the pumps for my superjet the piece marked in red in the photo and drilled!! What can it be used for? Better to leave it free or close it ???
 

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Kohldanielzimmer

Sierra Nevada Runoff Rider
Site Supporter
Location
Ahwahnee, CA
I believe older superjet pumps had a hose attachment that operated the siphon bilge. Later pumps were changed to a fitting on exit nozzle and that remains undrilled from Yamaha.

If you don’t have the bilge set up off it and don’t need dual cooling, close it somehow (epoxy, tig welder, etc)
 
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