This is my kart frame i just bought and i would just like to know if this normal or if it is damaged and also the left Side at the place onder the fuel tank is a bit more worn down
That type of wear on the chassis rails is ānormalā and called āflat spotting.ā
Once itās more than halfway through the tube thickness the chassis will be junk. Itās a little hard to tell, but this looks like minor flat spotting to me.
The level youāre showing wouldnāt prevent me from buying the chassis, but Iād IMMEDIATELY put on some chassis guards to stop itsā growth.
It can be touched up with a bit of sandpaper and Birel red spray paint, prior to installing the guards. Iād get the guards that physically cover the frame rails, not sit off to the side.
Good luck!
Thanks for replying im pretty new to the hobby so thanks for helping me i Will buy Some frame protection
Chassis protector is the first thing I install when getting a new chassis. Even good to put on later if you forget.
Iām not a massive fan of the plastic ones, they are quite thick and can bottom out. The metal ones are nicer and depending on the brand, weight a tad less.
Iāve run the ones Ted shared, those are the only plastic(y) ones I like.
I do like to run one under the seat cross member too.
Hereās another topic on protectors.
A little worn but no issues. As noted, get a set of chassis protectors to prevent it from becoming an issue. 
That chassis looks amazing for a used set of tubes. Zero concern for a starter kart.