Tim Richmond won his second consecutive NASCAR Winston Cup stock car race yesterday, beating Ricky Rudd by two seconds in the Budweiser 400-kilometer at Riverside (Calif.) International Raceway.

Richmond, in a Chevrolet, averaged 102.183 mph over the 95 laps for his fourth victory on Riverside's 2.62-mile circuit. He earned $36,450.

The 32-year-old driver from Ashland, Ohio, missed part of the season after a life-threatening case of pneumonia. He made his first series start last week by winning at Pocono.

The race was close until the final pit stops, with Richmond, Rudd, Geoff Bodine and Terry Labonte battling at the front.

Rudd, in a Thunderbird, wound up second, followed by Neil Bonnett (Pontiac), Labonte (Chevrolet) and Bill Elliott (Ford) . . .

Ayrton Senna retained his Detroit Grand Prix title with a decisive victory over Nelson Piquet.

Senna, who won the Monaco Grand Prix this season, covered 63 laps in his Lotus Honda through the winding, 2.5-mile street course in 1 hour 50 minutes 16.4 seconds. He averaged 85.7 mph, winning by 33.8 seconds.

Alain Prost, in an unsuccessful attempt to pass Jackie Stewart's career victory total of 27, finished third in a McLaren, 45.3 seconds behind Senna. Gerhard Berger of Austria was fourth.

The victory moved Senna into first place in the driver standings with 24 points. Prost, who led entering the race, fell to second with 22.