I just purchased this 2008 yz450f a few weeks ago.Its my first time on a bike in about 5 years. I took it to the local track and found something concerning when I was cleaning it after the ride. It looks like the chain has chewed into the left inner frame rail.. The chain is adjusted to spec so I am not sure what has caused this... I am a pretty big guy who cases jumps on occasion.. Will this frame hold up over the next 3-5 years? Is this common at all? The bike is SWEEEETTT otherwise. Previous owner said it had 20-25 hrs on it and it looks and rides the part..