I am new to bikes and I just purchased a YZ450F and I have some questions. It's all stock. 1. It backfires a lot during deceleration. 2. Seems to bog if I just chop the throttle in neutral. 3. Seems to make what sounds like a loud knock at idle....but still has power and idles okay. And maybe sounds like cam chain rattle under a load. 4. Didn't know what jetting and needle placement is necessary. ...I live in grand Rapids Michigan and the temp has been anywhere from 40-75°F. Still seems to have all the same symptoms so far. 5. And was looking at getting the big gun slip on and didn't know the carb work for that as well.