I have a 2009 YZF450. After about a year of owning the bike I started it one day and went around the block. On my way back I went to get on the throttle a little and it killed on my. At first I thought it ran out of gas cause I had the fuel off. I checked it and it was on. Then when I went to kick it over it would kick through at all. I figured it must of jumped time or someting. I tour into it and sure enough it had. I purchased a new timing chain and a new chain tensioner for fear that it had malfunctioned. Got it all back together and it ran great for another 3 months. Then I was riding one day and I hit a jump. when I came down and landed the engine killed and I heard a metal crinkling sound. The rear tire wont turn at all. I havent tour into it to see whats the matter but im sure i'll have to do a new top end including new valves and maybe even a new bottom end. I'm sooooo frustrated with this bike. I dont think i'll ever buy another yamaha again(4stroke). I've always riden honda and most all of my riding buddies ride hondas as well and noone has ever had this problem riding a honda. On the other hand a cousin and another buddy bought yamahas right about the same time I did and both of them had the same problem. I started reading some forums and found a lot of other stories just like mine regarding the yamaha 450. I changed the oil and oil filter every 2 rides. If you're thinking about buying a 450 I would not buy a yamaha unless $$ doesnt matter. Anyways, at this point im trying to decided what to do with the bike. i defenetly want to fix it instead of just selling it as parts. Im wondering if I put enough after market parts on it if it would be reliable. Also, if i were to do a big bore kit which is the best one? I've read that if you do a big bore kit that you really should do a biger and better stroker. What should I do? Any suggestions?