What's coming out is a foamy white substance,
The race guys vent stuff into a catch bottle, something like a coke can or similar, suitably placed.
White foamy stuff is usually a sign of water or moisture in the oil,
and can be a sign the rings aren't seating too good, and there is a lot of combustion blow by.
A compression test can be useful here, tell you a bit about how the rings are.
If it doesn't ease off with more riding, you'd probably want to at least check it doesn't have a stuck ring or 2,
or may be more like new pistons and a rebore. The lack of oil burning suggests the oil rings at least are still good,
so the bores may not be that bad, just reringing it may suffice.