Tripped over this

He sells two engines..I'm looking at both. Sprockets are going to be a bear unless you get a hub adapter. One uses a 25H chain, and the other uses a t8F chain. To start with I'm going to make a rear sprocket for the one I choose and see how it goes. Later I might buy a Clam Shell hub adapter. I don't know if I can find a engine sprocket to match up. One engine is a 6 tooth, and the other is a 11 or 14 tooth. Finding a ratio of around 4.2 is the trick. I can find both in a 4 and 6 hole (sprocket) rear wheel mounting.
Seller has a high which doesn't mean anything...Look at both BGF and luckyearlybird (related). Trash vendors. The seller of those engines has responded to my emails within a day or two on a weekend. I've sent him 3 emails.

That gearbox looks like a HOOT 2nd generation, has either 1 or 2 sprocket internal #25 chain, most folks use grease inside, I've heard it's a good idea to change the chain inside to some quality #25 chain, rumor has it that there not that dependable, good start though.

Mac