Partial frame ‘Fun Karts’ is a go kart that just has as flat frame, no side supports, no roll cage, and typically is one wheel drive.
Usually a 5 horsepower engine is on them, and they are extremely quick.
The width on these go karts is typically not much wider than 24 to 30 inches.
We had a go kart that we used to play with and we called it the Mustang of go karts because it was so quick.
The main problem with the flat frame is strength. If a large enough bump is hit, the frame can take a set. I have welded up plenty of flat frame go karts, and finally had to revert to the Support Frame system to make the go kart hold together.
The support frame Fun Kart or Go Kart is basically a flat framed go kart with strengthening members brought up the sides for structural support.
The plans sold on this web site are for the Support Frame Fun Kart or Support Frame Go Kart design. The frame is designed with strength and performance in mind, so the extra weight from the support structure does not have an adverse affect at all.
With the support frame, the go kart can handle extra abuse, especially bumps and irregular terrain. Also with the side supports there is a measure of protection.