That's Kevin Schwantz at Willow on the cool-off lap after he won the second leg of the Kerker 100 / 1985 AMA Pro-Am Superbike race.
He's on the short straight between turns three and four, and that was the track before Willow shaved down that hill.
That was Sunday, April 27th, 1985.
He's on a Suzuki GS700E, which was the bike that Yosh built for their AMA Superbike return.
He's wearing a Fred Merkle replica Arai helmet.
Even though Schwantz won you have to remember that the only "real" factory involvement in Superbike racing was Honda with the VF750F.
Yamaha was only sponsering Sam McDonald, allthough they gave Jim Filice a couple of FZ750's that year.
After the AMA Superbikes went to 750cc's in '83 BMW, Ducati and Suzuki left the series (Yamaha was never in it), and after Rainey won the '83 Superbike title Kawasaki pulled out the next year.
In 84 and 85 it was a Honda show with a couple of ex-Muzzy/Kawasaki GpZ750's and a couple of semi-factory FZ750's to fill up the grid
Schwantz and the Yosh bike were the spoilers.
For that weekend there were 22 racers registered,
11 Hondas, 4 Yamaha's, 4 Suzuki's and 3 Kawasakis.
Some of the riders were Fred Merkle, Sam McDonald, Reuben McMurter, Ricky Orlando, Dale Quarterly, Wes Cooley, John Ashmead, John Kocinski, Scott Gray, "Scary" Carry Andrews, Kevin Schwantz and Jim Filice.