1972 Suzuki T500 motor case

[quidger]

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I was changing oil and discovered a small half rounded hole on the seam on the lower engine case where it mates with left side cover. The previous owner tried to make a screw fit into the hole that does not fit.
What is this hole for and should it have a bolt or screw threaded into it?


Thanks

[jabcb]

That little notch in the bottom crankcase half is also in the crankcases listed on eBay.
Crud tends to accumulate there & it looks like Suzuki intended the notch to be a drain.