White Tec with no numbers on shroud.

[mini one]

I picked this up as a "couldn't pass up" deal. You all know those right? Engine plate was missing, nothing for numbers on top of shroud. Numbers on that round casting on the side read :19-0-80
plastic fuel tank (looks like it was added from the looks of the angle iron mounts) Previous Owner said it was a 6 or 7 HP.

 

[cheezy1]

Looks like an early very late 60's - early 70s Big block Tecumseh. Around a 5HP. And yes...gas tank doesn't go with motor. Looks like it came off a bike with a remote tank such as this in the pic.

 

[sludgeboy]

The tag with the numbers is missing. It was riveted to the shroud on the side. Take off the head and measure the bore size. This will help you determine the exact HP.