Time has been good to "Bye Bye Birdie." So has the Harlequin Dinner Theatre.

An amiable cartoon of a musical when it popped up on Broadway in 1960, it has since acquired a patina of nostalgia and sweet innocence. This was the show that spoofed rock 'n' roll mania among the young and the hullabaloo surrounding the drafting of Elvis Presley (in this instance, the beer-swilling Conrad Birdie) into the Army. But the satire, never especially virulent, is now positively benign.

Juvenile delinquency, Ed Sullivan and the Ingrid Bergman-Roberto Rossellini scandal have long been dethroned as topics of concern, and Elvis' sainted image lies a-moldering in the pages of National Enquirer. There's no better measuring stick of the distance we've traveled than the not-so-knowing attempt of one of Birdie's teen-aged fans to curry his favor. "I can go out and get you a fix," she says, looking as blase' as she can, "if you'll tell me what it is."

What remains, however, is slick, bright musical comedy of the old school--the school that didn't worry so much about the integrity of its plot or the ultimate angst in a ballad. In short, with its succession of upbeat songs ("One Boy," "A Lot of Livin' to Do," "Rosie"), its running gags and its persistent emphasis on fun, it harks back to the revue more than it anticipates today's Sondheim-influenced musicals.

The Harlequin's production, awash in primary colors and pop-up sets, is engaging on nearly every front. It stars radio personality Johnny Holliday, of the chipmunky face and disposition, as Birdie's beleaguered manager. Yet another sign of times past: When Holliday pulls his felt hat down over his ears, and croons "Put on a Happy Face" to his loyal secretary, he is curiously reminiscent of Donald O'Connor. Liz Donohoe is snappily appealing as that secretary (part Spanish, in deference to Chita Rivera, who created the role) and Jamie Zemeral's spoof of Elvis skillfully blends oil and troubled waters.

The Harlequin seems to have a corner on burgeoning young talent (Claudia Lynne Miller, Tom Allen and Deborah Cristina Moore are definitely three to watch), and "Birdie," with its sunny view of the generation gap, is the sort of show that serves them well. A little more choreography would benefit this production, but otherwise it rides an unbroken wave of good spirits, and its nuttiness seems utterly without malice or too much forethought.

As a parting gesture before donning Army fatigues, Conrad sweeps into the hamlet of Sweet Apple, Ohio, to sing "One Last Kiss" to the president of his adoring fan club. The kids are in a tizzy, their parents are distraught, and soon all hell breaks loose. Well, heck, really. "Birdie" is no less likable for that.

BYE BYE BIRDIE. By Michael Stewart; music, Charles Strouse; lyrics, Lee Adams. Directed by William Wesbrooks; sets, James Fouchard; costumes, Karen Hummel; lighting, Michael Meath. With Johnny Holliday, Liz Donohoe, Deborah Cristina Moore, Lois Kelso Hunt, Jamie Zemeral. At the Harlequin Dinner Theatre through July 25.