Factory fill in rides

Was that 3 factory 450’s in the main at SLC, 6 if you count the Suzuki’s.

How come the factory teams don’t put some of the privateers on the bikes to fill in?

Surely works out for both parties, teams get a bike on the track, privateer gets an opportunity.

As a fan it’s good advertising still because if there’s a privateer getting a fill in, you take interest for sure.