Triumph 450 raced in Australia but not the US?

I think someone raced one this year in Canada too. But probably a privateer. 

A privateer or two raced them in the US this year as well

A lot of privateers raced it in Europe too.

Yeah it was funny seeing Aussie privateer Zach Watson in MXGP last weekend in what may have been the Triumph 450’s international debut?

Does Triumph have a homologated 450 as required for AMA racing? 

Ricky russell has been racing one in gnccs and national enduro, even won a national enduro two weeks ago on one

Yes. Canadian Julien Benek was the first guy to make the night show in SX this year. He raced it in Denver. 

French rider Tom Guyon made it at the 2025 french GP in St Jean d'Angely.

Cool, I didn’t remember that.

And Alvin Östlund raced it in the GP of Sweden

Would be interesting to know if Triumph has reached out to these guys as a learning lesson.

I saw once racing the 450 class the Czech MXGP in Loket.  Rider listed in the results is #474 Bryan Boulard.

Nagl also rode a 450 Triumph in the ADAC MX Masters this year and probably would have won it again if he was healthy. 

For every 450 there has to be at least a hundred 250's out there.

Whole lot less bad press if the bike blows up in Australia than if it did it here in the states. If it does it in Oz, they have time to fix the issue before a debut here.

No particular reason that the 450 Triumph would "blow up"...