The carb probably has all the internal parts ..just take your time and lay it out as you take it apart in a way you can just go in reverse order and put it back together ..take pics before you remove things.probably the hardest part and it's not really hard if you pay attention is the slide where your throttle cabl e connects has a small tab inside the carb that lines up with a slot in the slide and you have a needle on the end that will slide. Into your jet..you can do it if you just take your time and pay attention..as for tuning ..you will still have to tune even if you buy a new carb (edited)