Washington Bullet Mitch Kupchak will undergo back surgery Friday at Sibley Memorial Hospital. He said yesterday he expects to be recovered in time for the next National Basketball Association season.

"Every doctor I talked to, and I talked to six different ones, said the recovery wouldn't go past four months," Kupchak told The Washington Post, "and I'm counting on playing next year. I'm trying to convince myself to just get well, but I can't help thinking about playing as soon as I can.

"The game of basketball played an important role in the decision to have surgery, but it wasn't the deciding factor. The rest of my life was," Kupchak said.

His injury, which has been diagnosed as a herniated disk, kept the 6-foot-10, 25-year-old Kupchak out of most of last season's playoffs. He missed the entire NBA championship series in which the Seattle Super-Sonics dethroned the Bullets, 4 games to 1.

Kupchak said the surgical procedure, which will be performed by Washington neurosurgeon Dr. Aurthur Hustad, is a laminectomy.

"They aren't going to do anything structurally," Kupchak said. "A disk has slipped out and has a nerve pinched to the bone. They'll make an incision, free the nerve and then shave the disk so it won't rub the nerve again.

"It's major surgery, but it's not a serious, complex procedure," Kupchak added. "You just need a good neurosurgeon. Eight or nine days after the surgery you are on your own and walking around. After a month or so you start to swim and begin your rehabilitation."

Kupchak speaks as an authority on the subject because he had "the same exact operation four years ago" while a student at North Carolina. "This time it's just lower in the back," he said.

"I was out only three months then. I had the surgery July 12 and the first day we were allowed to have practice was Oct. 15. I was there."

The 1979-80 NBA season begins Oct. 12.

Kupchak took his time deciding what course of action he would take with his back because, he said, "there was a lot more to it than just basketball."

He said he consulted five neurosurgeons and an orthopedic specialist and then went to his parents' home in Brentwood, N.Y., last weekend to make the final decision.

"I had my own ideas before I saw the six doctors," Kupchak said, "and every one of their opinions was consistent. The score was 6-0.

"Once I was convinced I had to have the surgery, I went to see my parents to get their view. I put a lot of value in their judgment and I wanted to be sure they agreed with me.

"An athlete thinks about a seven or eight-year career and the game means everything to him," Kupchak added. "But parents realize it's a game and only a temporary occupation. It eased my mind to be with my family and have them understand everything. They feel I am doing the right thing and they've given me the support I need.

"There are a lot of people who admire you and like you and even some who love you, but no one looks out for you like your parents. Their only concern is 'what's best for my son' and they have no other motives."

Kupchak added that he wasn't told by any of the doctors he consulted that he had to have surgery if he ever wanted to play basketball again.

"Their opinion was that the best chance I had to lead a normal life or play basketball was to have the surgery," he said.

The decision to have the operation was one of the most serious Kupchak said he has had to make. He remembers four years ago when he made the same decision.

"I thought then that I would have that surgery and be okay the rest of my life," he said, "but here I am with the same thing again."

Dr. Hustad was unavailable yesterday, but a number of other neurosurgeons and orthopedic specialists queried said a three-to-five-month recovery period is normal for a procedure such as the one Kupchak will undergo. A lot depends, they said, on exactly what they find when they look at the troublesome disk and on how the surgery goes.

Bullet General Manager Bob Ferry was elated that the prognosis for Kupchak is for a quick recovery.

"Our reports from the doctor are very, very encouraging," Ferry said. "I would look at four months as maybe more time than he'll need from what they indicate. It doesn't look to be too bad."

Kupchak added, "I do feel better now that the decision has been made. Two days ago when I decided to have the surgery I stopped grinding my teeth and my hair started growing brown again. It had been turning gray." CAPTION: Picture, Mitch Kupchak