The Fat Lady is singing again for Dick Motta. It was learned yesterday that he and the Bullets have agreed to a two-year extension to his contract as coach.

The Bullets also have signed Bernie Bickerstaff, now in his sixth year as assistant coach here, for two more seasons.

Although Motta has yet to formally sign the extension, Abe Pollin, the Bullets' owner, said yesterday he was "delighted to have both Dick and Bernie with us. We've got the best headcoach and the best assistant coach in basketball; they've shown that.

"I wanted to do this earlier," Pollin said, "but we jut haven't had a chance. We didn't want to risk losing either one of them and we thought this was the best way to go."

Motta, who flew to Detroit with his players yesterday for a game against the Pistons at 8:05 tonight in the Silverdome (WDCA-TV-20), will get a healthy pay raise, probably to the $125,000-$135,000 level by the second year. He is earning $80,000 in the last season of his original three-year pact.

Motta came to Washington before the 1976-77 season. He replaced K. C. Jones, whose contract was not renewed by Pollin. Motta left Weber State to coach the Chicago Bulls for eight years, building them into a league power before seeing them tumble to a 24-58 record his last season.

Pollin was criticized for hiring Motta, a tough, no-nonsense coach who had problems in Chicago getting along with some of his players and whose philosophy of coaching a deliberate, tempo-controlling style of play seemed ill-suited for Washington's personnel.

After a disappointing opening season in which the Bullets won 48 games but lost to Houston in the playoffs, he coached the club through a series of crippling injuries and the loss of All-Star guard Phil Chenier to win the championship last June.

In the process, Motta's coaching was highly praised, especially during the series with the 76ers when the Bullets beat Philly at its own running game. Now both the club and the coach are recognized for the efficiently of the fast break, a change Motta finds amusing.

"People never recognize you have to coach with your personnel," he said in a recent interview. "I couldn't run in Chicago, but when I said I'd run here, people laughed."

Winning the championshop established Motta as one of this area's reigning sports personalities. His "Fat Lady" slogan was adopted by Bullet fans as their playoff battle cry.

The former high school teacher and country store owner has an engaging personality, an entertaining sense of humor and a keen basketball mind that long has been overshadowed by his legendary temper outbursts.

He is a fine public speaker, but he is more content wearing blue jeans and boots while either driving his pickup truck or fishing on his property in Idaho.

"When I came to Washington," said Motta, who is 4m, "I didn't know if I was at the end of the line coaching or not, after what happened in Chicago. I just wanted to be ready for the future, whatever it was."

Now, he says, he's never been more content. "Getting that championship ring did it," he said. "I know I'm more relaxed now. I feel good about my See BULLETS, D2, Col. 5 BULLETS, FROM D1 CONTRIBUTIONS TO THE TEAM, AND WHEN I GOT THE RING, IT WAS A GREAT THING FOR ME PERSONALLY.

"I WAS DRIVING OVER TO CAPITAL CENTRE THE OTHER DAY AND I TOOK A BACKROAD AND TURNED THE RADIO UP AND THOUGHT ABOUT HOW I WAS TO HAVE THIS JOB. A LOT OF NICE THINGS HAVE HAPPENED TO ME. I WAS MELLOW.

"I'M NOT LOOKING AROUND CORNERS ANYMORE IN MY CAREER. I'M STILL SCARED GOING OUT THE DRIVEWAY TO GAMES, BUT IT'S NOT LIKE BEFORE. I'M NOT BURNING UP IN SIDE AS MUCH. I LIT A LOT OF FIRES INSIDE BEFORE. NOW, I'M KEEPING THIS ALL IN PROPER PROSPECTIVE.

"I RESPECT THIS JOB AND I THINK PEOPLE RESPECT ME. I GOT HERE THROUGH A LOT OF HARD WORK AND I TOOK SOME CHANCES. BUT LIKE I TOLD MY DAD, IT'S A GREAT JOB AS LONG AS YOU WIN 42 GAMES EVERY YEAR. THEN YOU HAVE A GOOD SHOT AT THE PLAYOFFS."

BUT, MOTTA ADMITTED, THERE ARE STILL SOME ANXIOUS MOMENTS.

"I WOKE UP FROM A DREAM THIS MORNING," HE SAID. "ALL I REMEMBER FROM IT IS THAT WE JUST LOST THE SEVENTH GAME OF THE NBA championship." CAPTION: Picture, Dick Motta