You'd better hope the rope doesn't get all tangled up once inside the cylinder. You'll end up pulling the head if it does.
Just use air. As long as your valves are sealing properly you won't need to worry about one dropping.
Besides, you won't be introducing fibers or other junk into the cylinders with air like you do with the rope trick. That rope will be clean only on the first cylinder. After that, it's dirty.