I don't think that guys "one problem causes all" answer is doing anyone any favors. There was no mention of a worn out, or badly adjusted clutch as being a culprit. Or primary oils being too heavy or thin. Matching engine speed to a given shift point will allow you to shift smoothly without using the clutch.Heavy oil in cold weather causes drag on the clutch plates, and can cause you bike to bang into gear or lurch forward. If your bike uses the same oil for the motor and transmission, as it gets older and shears out of grade, that can cause it to be hard finding neutral. Of course bent or damaged shift dogs or shafts can cause hard shifting,but most of the time the answer is alot simpler to remedy the tearing the motor or trans apart.,,