When sex researchers Bernard D. Starr and Marcella Bakur Weiner set out two years ago to study the bedroom lives of America's elderly, they framed their questionnaire carefully. They wanted to avoid "stepping on what we thought were sensitivities."

"We were being delicate," says Weiner, 55, adjunct professor of psychology and gerontology at Brooklyn College of City University of New York. "Should we say orgasm ?"

"We didn't think they knew the words," says Starr, 45, Brooklyn College education professor, pshchologist and researcher in gerontology.

But when the early responses started coming in, "we were stunned," they-say, by how many of their 800 subjects -- ranging in age from 60 to 91 -- felt the questions failed to touch the full scope of their sexual experiences.

"How come you don't have any questions on affairs?" they wrote. "Why didn't you ask about oral sex?"

That prompted the pair to revise their questionnaire "to include the broadest possible range of questions that we would ask adults of any age."

Even they had found themselves trapped, they confess, "by the very stereotypes we sought to break down."

There is a widespread assumption in our society, says Starr, "that older people are not interested in sex. Some young people don't even think there's sex after 40."

Weiner says she always felt that the gray-haired couples walking hand-in-hand down the street "cared about each other" -- that they enjoyed "a caring, loving relationship." But she also figured that it was only "a spiritual thing."

Now they are convinced the results of their study -- just published as The Starr-Weiner Report on Sex and Sexuality in the Mature Years (Stein and Day, 302 pages, $14.95) -- will correct their false picture "that everything is downhill, that you will lose power and potency."

Senior citizens, says Starr, "are interested in sex. They need it. They get it whenever they can. They are total, complete humans."

Among their findings:

For 75 percent of the respondents, sex is the same or better now compared with when they were younger. "It opened our eyes," says Starr. Many say they have more time for "unhurried" sex; they have shed inhibitions or they no longer have to fear pregnancy. Explains an 81-year-old woman: "Better, as we have more time for bed-talk and are more relaxed."

80 percent say they are "currently sexually active" -- 50 percent reporting intercourse once a week or more, and 12 percent claiming three times a week or more. Nine of the over-60s say they engaged in sex daily. (Many of the inactive are widows who lack sexual partners). Starr and Weiner calculated the average frequency for their 800 subjects to be 1.4 times weekly, about the same frequency for 40-year-olds in the earlier Kinsey studies.

(Contrary to commonly-held beliefs that frequency declines sharply with advancing age, the researchers found the figure drops only to 1.2 times weekly for the over-80s.)

99 percent say they desire sexual relations, "if they could whenever they wanted to." These figures, say Starr and Weiner, "unequivocally challenge the belief that older people are beyond sex." Says a 79-year-old widow: "I'm ready and willing, but there just aren't any suitable men around."

69 percent of the women surveyed desire orgasms as an essential to a good sexual experience, and 72 percent say they have them "most of the time" during lovemaking.

39 percent of the group say they have experimented sexually with a variety of possible experiences now more openly discussed than when they were young. Writes a 73-year-old woman: "I think we tried all the ways I ever heard of." Add Starr and Weiner: "Older people can be as adventurous as the young."

It is true, the pair notes, that older men do not achieve erections as easily as when they were young. But, they have found, "these natural changes in physical functioning do not have to hamper older people from engaging in satisfying, even ecstatic sex, nor should it stop them from actively seeking out sexual experiences."

To acquire their sample, the researchers spoke to senior-citizens groups throughout the country and distributed more than 5,000 copies of their 50-item questionnaire. The 800 (35 percent male, 65 percent female) who took the time to fill them out could, they acknowledge, be those who are the most sexually active. They feel, however, their 14-percent response rate is impressive and indicates "the questions we asked were tapping a vital and hidden part of their lives."

In some cases, administrators at community senior-citizen centers were reluctant to permit the pair to discuss sex and sensuality. "You'd open a can of worms," one told the researchers. But when they spoke, says Starr, "The response was overwhelming. It was like liberating a POW camp. There was hardly a senior center where a topic like this was discussed."

From their study, the authors conclude that the older generation has "responded to the same sexual revolution" as their children. Many are accepting of such childhood taboos as nudity, masturbation and homosexuality "for those who choose it."

Their sample, they say, sees sex continuing to have "a postive effect" on their lives. "It contributes to their well-being."

As an 88-year-old man puts it: "I love my wife and sexual relations."