Jaden Smith, left, and Jackie Chan star in the remake of “The Karate Kid.”

Let’s put the shortcomings of the new “Karate Kid” in perspective. The 1984 original, directed by “Rocky’s” Oscar-winner John G. Avildsen, was hardly a cultural treasure. It was wildly implausible and corny, but if it hit you at the right point in your underdoggy adolescence, it generated warm memories.

The remake is equally farfetched, but lacks the innocence that made the first film so likable. The new “Kid” feels like a big-budget audition reel for sweet Jaden Smith, with Will and Jada Pinkett Smith hovering above the bloated 135-minute project as doting parents/ producers. An air of calculation overhangs the whole enterprise like a storm cloud.

The film follows 12-year-old Dre Parker (Smith) and his single mother, Sherry (Taraji P. Henson) on a job transfer from decaying Detroit to vibrant Beijing. Dre’s transition is complicated by his lazy, disrespectful nature, his crush on his Chinese classmate Meiying (Wenwen Han), and vicious bullying by schoolyard thug Chen (Zhenwei Wang) and his henchmen.

Dre begs his mom to enroll him in a kung fu academy for self defense, but finds an unlikely mentor in his apartment’s laconic handyman, Mr. Han (Jackie Chan). In the course of many training montages, he drops his bratty attitude, absorbs a dose of Buddhist humility, and learns to stand up for himself.

Smith is a cute kid, but fundamentally miscast. The protagonist in the original film was in his mid-teens, a young man in the making. Here, prepubescent seventh-graders enact heart-thumping romance and bone-thumping beat-downs, which makes for uncomfortable viewing. Ironically, Smith radiates a self-possessed confidence that makes him seem less vulnerable than his puppyish predecessor, Ralph Macchio. The little leading man has a couple of scenes here where he weeps with a doe-eyed professionalism that verges on the robotic.

He’s impressively agile in his endless training scenes, but his acting muscles are not so limber. His mushy kissing scene with his girlfriend looks more painful than the endless walloping he gets from the brutish Chen.

And what about Jackie Chan? He is stuck with some Zen howlers here, explaining how kung fu is like life. His tragic back story, like the film’s needless excursions to the Forbidden City and the Great Wall, really ought to have been saved as DVD extras. Chan is playing an older, wearier character here, and his shambling body language is persuasive. Either he nailed this duffer’s physicality or all those stunt injuries are finally catching up with him.

The climactic scene, the standing-room-only little league kung fu championship, is a numbing flurry of fast cutting, ear-bruising sound effects and spinning crane kicks. Director Harald Zwart (“The Pink Panther 2”) is better at drawing out the tension before the bouts, when the opponents eye one another warily. The David and Goliath mismatch plays out as it must, but it’s hard to shout approval for pint-sized lads clobbering each other.

The recent superhero spoof “Kick-Ass” had the wit to turn that kind of child-abuse imagery into a grand sick joke. “The Karate Kid” invites us to cheer the spectacle for real, and even when the good guy triumphs, that spoils the fun.