I've drowned an XR600 twice, really badly. , but so does making dumb calls. Though in my defence, I guess there really weren't many options...

I discovered that apart from agreeing with the wise words above, a big danger with hot engines drowned in cold water (the usual scenario, obviously) can be warping of the combustion chamber, as distinct from the gasket surface. The very hot exhaust valve area, especially, can be vulnerable. Result? The valve guides' longitudinal axes aren't centred in the ports any more, which meant cutting the seats off-centre to avoid replacing the whole head, and new valves.

Drowning can be very bad news, though the bike did many thousands of km without any drama after the repairs. Pure luck, methinks. I suppose water-cooled engines are less likely to suffer, but...