Plaintiff was injured in an accident on his Yamaha dirt bike.  He said the authorized Yamaha dealer from whom he bought the bike had installed the throttle mechanism improperly, leading it to fall off the bike, causing the accident.  The jury verdict and judgment in favor of Yamaha Motor Corp., U.S.A., the US distributor of the bike was reversed because the trial court refused to give the proper proposed jury instruction that would have required the jury to hold the distributor liable for the dealer’s negligence in assembling the bike.  California law places “responsibility for defects, whether negligently or nonnegligently caused, on the manufacturer of the completed product . . . regardless of what part of the manufacturing process the manufacturer chooses to delegate to third parties.” (Vandermark v. Ford Motor Co. (1964) 61 Cal.2d 256, 261.)  The same rule applies to distributors.  Yamaha “cannot delegate its duty . . . [and thus] cannot escape liability on the ground that the defect in [Defries’s bike] may have been caused by something one of its authorized dealers did or failed to do.” (Ibid.).