2020 KX 450, 25 laps, 40 minutes of riding and bike is still smoking and now oil level is reading super low on the sight glass compared to when I first brought it home.

Take it back to the dealer and tell them to fix it, don’t pay a cent.
they should be good about it, if it’s brand new and you bought it from them..

Id keep the dealer in the loop about you concerns and what steps you are taking so it is clear everyone is on the same page. See what advice they give you.. that way you have the best chance of working together to find a solution

Dealer issue......take it right back and ask for a new bike as this one could be a lemon so you are the one who will suffer further down the road.

Take....it.....back

How bad is it smoking? The rings haven’t even seated yet with that much time on it.

Drop it off at dealer Monday and go home.

Rings are not seating. (Or maybe are broken) Let the dealer put in a new set with quick hone, and run it. At least that is what we do in the piston powered aviation world. But we also run mineral oil for break in. If smoking when accelerating, its most likely a ring issue.

Rings will have seated in the first few thousand revolutions if it was built to spec. They don't need hours these days.
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Sounds like maybe one of the oil rings were folded over at at the factory or a seal wasn't installed right. This is a factory defect for sure. As stated above, take it back to the dealer asap.

Look at the spark plug. If the oil is burning in the combustion chamber the spark plug will show you.
If the plug is clean with no burnt oil residue the top end might be okay.
Any crusty black soot on the plug is your take it back to the dealer moment.
Oil in the muffler should burn out fairly quickly, one ride should do it, if it persists and your oil level is continually low then you have the answer, the top end is leaking.

The dealer should definitely be able to help you with this, I would contact them ASAP something not right there

Take it back. Even though there is “no warranty“ Kawi will usually work with you.

This sounds like a cracked ring , or possibly an oil seal that's seeping a little. My 08' Honda had a seal dry out a little and it seaped , and I was experiencing the same issue. It ended up roaching my packing in the silencer , but that was an easy fix. Like the guys said above , being brand new , take it back and don't ride it until they fix it.

This is the first time I've heard of anything like this on the new Kawi. I would make sure to talk to the dealer as quickly as possible. Bummer but it will get fixed