Is jetting a quad a hard process?

 

Also why do you need to jet a quad? Just for better flow of gas and such?

 

Not really hard. More time consumming and trial and error.

For an engine to run correctly you need to have the correct fuel air ratio. For best power you need somewhere around 12.5 parts air to 1 part gasoline.

There are many reasons to rejet. One is if you move from a higher elevation to a lower elevation. At a lower elevation you need more gasoline because there is more air.
Another is if you mod the engine. If you put a better air cleaner and pipe on, the engine will flow more air so you need more fuel.

Make sense?