There are several movies in which a killer wears a motorcycle helmet while targeting victims in a house. Without more specific details, it's difficult to pinpoint the exact movie you're referring to. However, one notable film that features a killer wearing a motorcycle helmet is "The Strangers" (2008).
"The Strangers" is a horror film directed by Bryan Bertino. It revolves around a couple who are terrorized by three masked assailants who invade their secluded home. One of the assailants wears a motorcycle helmet throughout the movie. While this film may match the description you provided, it's always possible that there could be other movies with similar scenes or plot elements.
If you can provide additional details about the movie you're thinking of, such as any specific actors, release year, or any other distinctive scenes, it might help in identifying the exact film you're referring to.