Cezar,
I can't tell what brand your kart is, but it's definitely the Offset type of frame made for left-turn Oval racing.
Notice how far inboard your left axle bearing is located compared to the right-side axle bearing? Besides that, your leftward-angled steering column and the location of your seats front-mounting tabs are also clues this is an oval racing chassis that typically have their seats located way over to the left side to help transfer the driver's weight.
As your researching the 30 or so different brands of Oval racekarts made over the years, keep in mind your type of Offset kart also commonly goes by the generic terms of being a "LTO-chassis" or a "Left Turn Only" chassis or kart.
(The other/more common type of side-engine racekarts that were designed for competing on paved road courses with right & left turns, typically go by the generic terms of being a: "Straight Rail Chassis", or a "Sprint Kart". You'll notice the steering column, seat and axle bearings are much more centered in the frame on those types of racekarts...)
The design of your (front) Nerf bar mounting tabs tells me your kart was most likely made back in the 1980's or 90's. Because It's too modern looking for a 70's-era, and most all racekarts made after the year 2000 came with non-angled/tubular front Nerf mounts that look exactly like your rear Nerf bar mounts.
Do you have the front/rear bumpers and Nerf Bars?
Posting more pics with those installed might give us some good clues as to what brand it is...