In a pinch, you can screw a 2x6 to an open stud wall (across two studs) and hang a motor right on the wall.
Or, screw a 2X6 to a single studs side, bringing the 2X6 outward (2 feet, or as needed), perpendicular to the wall, and either screw a 2x4 leg to the outer end, or use a single saw horse to support it. The advantage of the perpendicular setup, is you can extend the 2x6 further and hang multiple motors or other junk, as well as run the motor in a trash can/barrel.
You can use a dolly as Sumner did, but note the bottom, he extended the foot out farther. You have to do that or it will tip over. Makes a good portable stand.
There are some plans online using 2x and plywood, and they work okay, but they are generally quite heavy and dont hold up all that long. The dolly idea can work pretty well, especially if you want portability.
(I am going to get flack for this, but) A cheap and dirty way that works with two stroke motors (that are drained of water and fuel first), is turn them upside down and set the cover down on a towel. You can then use a regular dolly, just use a bungee cord or tie strap to tie the motor to the dolly. I have even set them up on work benches in the corner, and up on a garage shelf and left them sit all winter. Never bothered them a bit. Just remember they have to drain of water first.
You cant do that with four strokes as the oil would run out the breather and make a total mess of everything.