Three of the top American riders -  Marty Tripes on a Spanish Bultaco, Steve Stackable on a German Maico and Jimmy Weinert on a Japanese Yamaha.

Jim Pomeroy was wearing blue and yellow Pennzoil coveralls at the start of pratice.  Not exactly high fashion but I thought it was a cool way to advertise oil.

Jim Weinert and Roger DeCoster had all the Number 1 stickers covered that year.  Weinert was the 500cc U.S. Champion and DeCoster the 500cc World Champion.

The great young hope for the American's was Marty Smith.  He was 125 National Champion that year and was riding 500's for the first time.  He lead one of the motos for several laps that day.

The Honda pit set up was considered elaborate back in the day.  No semi's in sight.

The Husqvarna pits were even more spare. 

For a few laps Pomeroy lead the second moto but DeCoster was on his tail and eventually took the lead.