scrollable iframe?

Is there a way to make my frame have a scroll bar if it’s taller than the page? Shouldn’t it do this by default?

For example: http://utahrevolution.com/1278-e-125-n/

I have manually set the height to 1200 px, which adds a ton of black area on the main page, but if you click the photos or tour link, it isn’t tall enough, and there’s no scrollability.

Any help?

http://ww.wp.xz.cn/extend/plugins/advanced-iframe/