The Predator motor or a dozen other brands can be used in the vertical or horizontal position. It will lubricate properly either way & hundreds of bikes use them in the vertical, though the factory mounts them horizontally...like a go cart or generator engine. They are Honda clones made in China and Taiwan, but Rick S. uses the newer real deal Honda power. Lots of info on how to build motor mounts, and make a few minor changes necessary to run them in the upright position...easy stuff really. Also clutch suggestions And how to fabricate jack shafts to transfer power through belts or chain. Many are using a CVT like the Comet to transfer power from engine to the rear wheel. Lots of examples in the threads of this forum & answers to your questions as well, which will save you time, money and headaches. It's fun to read these threads and learn, but nice to know you can ask questions and get answers. No one knows it all but some of these guys are getting close!
Rick C.