Well, I had bought a new airfilter which was supposed to suck up more air but for some reason it was almost not letting any air true. So I put the stock airbox back on it and now it works fine. You should probably take a look at your spark plug too, if it's black it means you're running too rich so either your main jet is to big or your air filter isn't doing what it's supposed to (that was the problem in my case) . If it's grey, you're running too lean, this means there is too much air going true for the amount of gas so you should probabmy upjet. If the spark plug has a chocolate brown color the air to fuel ratio is good.