"Rupp kart. A narrow hoop Dart A-Bone" (Hellion)
"that might be a Dart kart...
the rear axle hangers scream Rupp the narrow steering hoop suggests some later year (1965 ++)...
and the front axle support somehow tickle my Lancer senses..
Then again it might be a Clark Cyclops that someone added the front axle support to" (Sid)
Maybe look up some pics, of those karts for comparison
It's a Rupp. It has a lot of the features of this 1967 Dart Kart that purports to be an authentic restoration and not only has Mickey Rupp's signature on the floor pan but also came with a photo of him sitting in it: https://bringatrailer.com/listing/1967-rupp-d-300-2/
Part of the problem of ID'ing a kart is that we assume it is original, unmolested and a veritable 'time capsule' that has been sitting ever since it was last used, and in its original condition.
Based on the pedals, if they are original, and the location of the engine mount I'd have to presume it is a Rupp D-300 based on the D-300 photo below. The other photos are useful as they show measurements of the different models and the 2nd one has a boy riding a similar kart with similar pedals that seems to indicate that Rupp fun karts used those pedals while the racing karts have the "L" shaped pedals:
No, never seen Ken Bar pedals like that. If they are not proprietary Rupp pedals (who knows?), they can be either Kartco or Clark aluminum pedals, but I say that because of the "style" of pedal. They're quite distinctive. Some of the pedals are smooth and some have a serrated or grooved surface. It's got to be one manufacturer that was making those and supplying them to the kart mfg's.