My Bodyguard

Clifford Peache (Chris Makepeace) lives in an upscale Chicago luxury hotel with his father (Martin Mull), who manages the hotel, and his eccentric but loving grandmother (Ruth Gordon). Clifford spends his nights with his family relaxing on the rooftop patio and spying on the neighbors through a telescope. He is the new kid at Lake View High School, where he arrives in a hotel limousine.
Clifford becomes a target of abuse from a bully, Melvin Moody (Matt Dillon). Moody and his gang of thugs, Dubrow (Richard Bradley), Koontz (Tim Reyna), and Hightower (Dean R. Miller), regularly terrorize and extort lunch money from other smaller, timid students, allegedly to protect them from a school outcast, the large, sullen Ricky Linderman (Adam Baldwin). According to school legend, Ricky has killed several people, including his own little brother. A teacher (Kathryn Grody) tells Clifford that the only violence she's aware of from Ricky's past occurred when his younger brother died accidentally while playing with a gun.
Clifford works up the nerve to approach Ricky and asks him to be his bodyguard. Ricky refuses, but the boys do become friends after Ricky saves Clifford from a beating by Moody and his gang. Ricky has emotional issues over the death of his 9-year-old brother a year earlier, and is slow to come out of his shell, but has been rebuilding a motorcycle that he cherishes. The friendship between the two boys is strengthened as Clifford successfully helps Ricky search junkyards for a hard-to-find cylinder for the motorcycle's engine.
As Clifford, Ricky, and a few friends from school, including fellow victims, Carson (Paul Quandt), Shelley (Joan Cusack), and an unnamed girl (Jennifer Beals), eat lunch in Lincoln Park, Moody and his gang approach. Moody has enlisted the help of an older bodybuilder named Mike (Hank Salas), someone he announces is his bodyguard. Mike bullies, intimidates and physically abuses the younger Ricky, and vandalizes his motorcycle before Moody pushes it into the lagoon. Ricky runs away. He later comes to Clifford to ask for money, ostensibly to pay for pulling the motorcycle out of the lagoon. Feeling used, Clifford follows him and the two argue before Ricky reveals to Clifford that he accidentally shot his brother while babysitting him at home. As a result of the accident, he is overwhelmed with guilt and remorse.
Moody and Mike later return to the park to further bully the other children and start a reign of terror. Unbeknownst to them, Ricky is also there retrieving his motorcycle. As Ricky attempts to leave with the bike, Moody notices and announces that the motorcycle now belongs to him. Ricky refuses the demand, so Moody summons Mike and the two begin to fight. Ricky gains the upper hand before Moody jumps on his back. Seeing his friend in trouble, Clifford manages to pull Moody off. Ricky beats Mike, knocks him unconscious, and then turns his attention to Moody. But instead of fighting Clifford's battle for him, he urges Clifford to fight Moody himself while coaching him. Clifford is afraid, but when he finally lands a solid punch and breaks Moody's nose, winning the fight, he realizes that Moody the bully is weak and cowardly. Ricky takes his bike back and as the children all leave together, he jokingly asks Clifford to be his bodyguard.

Question: What has Ricky been rebuilding?
Answer: Motorcycle