I recently purchased a 01 YZ426F that was in great shape for $300, had the crank rebuilt and everything reassembled for $200 so I'm not to deep in to this thing. My question is do I need to purchase a new timing chain and timing chain tensioner when doing the top end rebuild? both are original. I've heard you have to do it every time you do a rebuild; but I've also heard that you almost never need to replace them? I'm trying to fix this bike up for as little as possible so if I do not need them that would save me quite a bit of money.