At 40 hours the trusty YZ450F is better suited to me personally than it was, but it also looks a lot less shiny than it did at zero hours. This bike has been ridden hard including multiple full-throttle MX-style starts, timed motos with pros in the saddle and sessions screaming its guts out in a vain attempt to impress the radar gun. Since then I have used the YZ for moto-track practice riding and as a serious high-desert mountain trailbike. To make the YZ fit me better and adapt to my intended use, I found some 6mm spacers to raise the handlebar mounts. Factory Effex makes a stick-on seat "bump" that is very dense foam. I like the density better than aftermarket seat foams, so I ordered two bumps, cut the large ends square and stuck them to the stock seat with the cut ends touching. Then a Factory Effex seat cover went on over the now-taller foam. To protect the bike, make it more off-road-worthy or to ensure reliability I also added some products: a Trail Tech kickstand, Shock Sox neoprene fork protectors for the lower tubes and LightSpeed carbon-fiber covers for the upper tubes.I did some recycling, too: My Scotts steering damper got one of Scotts' cool Yamaha mounting kits, but the damper follows me from bike to bike. I love the safe feeling it gives me, and it saves energy. A set of Pro Moto Billet flag-type hand guards made most of the year on one of my bikes in '08, and they still looked good, so they are racking up more time on the 450. We added the FMF Ti Q muffler for our shootout's off-road impression, and the YZ loved the stealthy Q muffler, so I run it off-road and most of the time at the track. At about 33 hours the stock chain and sprockets were shot to the point that I was worried while riding on the track. I used Yamaha stock sprockets, but wrapped them with an RK X-ring chain, and I went for the premium gold one. I like the look of the Olkom USA graphics, so they went on with an IMS 3.1-gallon tank. I couldn't get the sag right for my weight, so I had optional Yamaha stiffer springs installed front and rear. That worked great on the 2007 YZ450F but made the '09 feel heavy, and it is too stiff for all-around riding, so it looks like the next 40 hours will see a suspension mod.Through it all the YZ has endured no major crash damage and there have been no mechanical disasters. The valves are at the tight end of the spec, but have never needed adjustment. That isn't to say the YZ made this 40 unscathed. One air filter looked suspect on the sealing lip, so we tossed it. The clutch had been used hard, and a routine inspection showed discolored plates. It wasn't slipping, but we felt it was best to replace the plates and the springs. Other than those small issues, we've kept up on oil changes with Maxima four-stroke oil, FFT filter oil and suspension fluids when we replaced one leaking seal.All told, the YZ is still hanging tough. It feels tight and fresh still despite fast and heavy riders putting most of the hours on it. I don't anticipate any issues to arise, either, though I will look into the suspension upgrades, repack the Q and keep a closer eye on the valves. In my opinion, there isn't a better motocrosser to choose for a do-everything bike. Putting hours on this baby is not a chore.