Why not? I guess because it is a hobby, and I want it to stay that way. And, since I am not an experienced machinist I have to take my time. This model took 18 months of part time work to build and another 6 months of tinkering to get it running like the real ones. Building a scale model invariably creates additional problems that take time to sort out. Just figure the volume of a hypothetical cylinder and then scale it to 25%, and see how well the volume scales. Similar issues with flywheel inertia, fuel vaporization, ignition shorts when 18,000 volts gets too close to scale components, etc. Getting a model running well can sometimes takes a long time. These challenges can be fun, but can also be exasperating at times. That's where forums like Fieldlines.com can be so helpful.
Jeff