KANSAS CITY, MO., JULY 17 -- Three games ago, the Baltimore Orioles told Eric Bell to cut the fancy stuff. After three months of throwing inside, outside and up and down, they told him to try throwing down the middle.

The result is that he has gone from the edge of demotion to Rochester back to being the reliable, polished starter the Orioles expected, and he was just that again tonight in a 3-1 victory over the Kansas City Royals before 38,059 at Royals Stadium.

Bell (7-7) won for the first time since June 20 by allowing six hits and a run in 8 2/3 innings. He walked none and struck out a career-high nine to help the Orioles to their third straight victory.

Eddie Murray's single scored Bill Ripken in the eighth inning to break a 1-1 tie. The Orioles got only seven hits off three pitchers.

An RBI single by Ray Knight gave Bell a two-run lead to take into the ninth, and two batters later he was within an out of his first major league complete game. Danny Tartabull then singled to left.

Bell had thrown only 101 pitches and said later: "I wasn't tired at all. In fact, I was strong." But Orioles Manager Cal Ripken Sr. saw it differently. "He was tiring," Ripken said.

So he waved to the American League's least reliable bullpen and brought in one of its least reliable relievers, Tom Niedenfuer. In a season of gambles, this was perhaps his biggest, taking a game from a sharp starter and giving it to a shaky reliever.

Niedenfuer threw six straight balls, four of them to Frank White. But after he went to 2-0 to Bo Jackson, he threw three straight strikes, the last a fastball that Jackson took. The save was Niedenfuer's fourth this season and second in two nights.

"We've told him to take a different approach to pitching, and it seems to be working," Ripken said. "I can't say what that approach is. I'm not going to reveal it."

The Orioles also had been working with Bell, and the problem wasn't quite so complex. They wanted him to throw strikes, to do better than 51 strikeouts and 51 walks, which is what he had when tonight's game began.

"We just told him to throw it down the middle," catcher Terry Kennedy said. "He's got such great movement that the ball will never end up down the middle, anyway."

Bell said: "That's not quite it. It's just that in the minors I never threw to locations early in the count, and I usually got ahead. Since I got up here, I've been trying to throw in and out, in and out."

It was Cal Ripken Jr. who suggested he try throwing some pitches down the middle, and he said: "That's got me going again. I was getting in front with my fastball early and keeping them off balance with my change. I don't know if I'm over the hump, but I'm sure feeling better about myself."

The Royals scored their run in the third when Willie Wilson tripled and scored on Lonnie Smith's grounder. Only two other Royals got as far as second base.

Bell and Royals starter Mark Gubicza (7-9) were in a 1-1 game for seven innings, but in the eighth, Murray's single scored Bill Ripken for one run and Knight singled for another.

The Orioles got a 1-0 lead off Gubicza in the third when Kennedy led off with a single and went to second on Larry Sheets' groundout. Mike Young grounded back to Gubicza, who caught Kennedy off second base. He threw to third baseman Kevin Seitzer, who ran Kennedy back toward second, then threw the ball wildly into right.

Kennedy and Young ended up on second and third, and Kennedy scored on Alan Wiggins' infield grounder for a 1-0 lead.

Wilson's triple got the Royals a tie in the third, and the game remained at 1-1 until the eighth when Bill Ripken led off with a single to left and stole second.

Gubicza walked Ripken Jr., and Royals Manager Billy Gardner brought in left-hander Jerry Don Gleaton, who had not allowed any of his last 13 inherited runners to score. That streak ended when Murray grounded a single to left for a 2-1 lead.

The RBI was Murray's 59th of the year and places him 10th among American League hitters. He's tied for fourth in homers with 21, and the single also extended his hitting streak to 12 games.

Gleaton struck out Fred Lynn, and Gardner brought in right-hander Dan Quisenberry to pitch to Knight. The move was booed loudly and even more so when Knight singled to right-center for a 3-1 lead. Knight had been 13 for 89.

Orioles Notes:

Mike Boddicker, who left Thursday's game with back spasms, will be checked out by a Royals team doctor this weekend. What concerns the Orioles is that the pain didn't cease even after he was given seven days between starts. "I just want to find out what's wrong," Ripken Sr. said. "I just don't want him to have to keep pitching in this agony." . . .

To make room for Mike Flanagan, the Orioles put reliever Tony Arnold (sore back) on the 15-day disabled list. Flanagan will start his first game since May 17 Saturday afternoon, and he'll be watched closely by a couple of teams. One is the St. Louis Cardinals, who may be interested in trading for him . . . Arnold and Flanagan became the Orioles' 44th and 45th roster moves this season . . .

Home runs by parks: Memorial Stadium 150, Kingdome 139, Anaheim 128, Wrigley Field 127 and Riverfront 124 . . . Ripken Jr. has one homer in his last 28 games . . . Kennedy started his 81st game tonight, which is 21 more starts than any other American League catcher has had. Next is Toronto's Ernie Whitt with 60 . . .

The Orioles have made 59 errors in their first 90 games. Last season, they made 81 in 90 games.