A mad scientist grandfather invents a genetic transformation machine and his 4 year old grandson acc

A mad scientist grandfather invents a genetic transformation machine and his 4 year old grandson accidentally turns his body into that of a 30 year old man. Baby Bobby escapes and runs around town as his siblings try to catch him before their parents get back from vacation AND before the bad guys get to him first. The machine is worth a lot of money and they only have a day before the machine loses its capabilities to change baby bobby back.