I think it's a Simplex steering wheel on a homemade kart... but it's very well made kart IMO.
Actually that's a Kelch "semi" wheel steering wheel, vintage, and often seen on Manco karts and Sears re-branded Manco karts.
Wheels are "Manco" but also seen on a few other manufacturer's karts and bikes, but more well-known as a Manco wheel.
The mystery deepens. What do all the stickers and decals say? It also appears that someone took the time to rivet on some kind of nameplate on the rear of the kart. What does it say, best you can tell?
Thanks, found a manco that was square tubing and mine has manco rums and steering wheel. Wandering where they got the Simplex decal now.
A Manco with square tubing? That I'd like to see, since you're suggesting it came that way from the factory.