I noticed the other day that my yz450f likes to knock some times and other times the engine stays quiet. Recently though it is knocking loud and wont stop. It has hesitation also on throttle response even though I have the jetting is set to stock and everything on the bike is stock. ( I bought the bike from someone however and see that the top end bolts have wear on them, I dont know what the top end could have in their) The knocking sounds exactly like pre ignition even though I am running 93 octane fuel. Has this happened to anyone else? The manual says to use 95 octane or higher ( I doubt anyone does that for a stock bike) anyways does anyone think that if I buy Sunoco 260 gt race fuel that the knocking will go away. I need help with this, my bike runs like hell. Also If I give the bike more than a quarter throttle fast the bike bogs hard and after high rpms it likes to pop.