How much money did you make last year racing? None? Then you must be in it for the fun, which makes the YZ125 the bike for you.At 160 pounds and racing Vet Novice, I don’t think I give up anything in lap times with this little bike. I’ll admit passing is much more challenging, and a ripped start straight might as well be tilled with Kryptonite, but everywhere else I am loving this bike.I was happy to grab it as my Long Haul bike, but then realized I had to think of something to do to it. In stock form the bike feels light, makes great power and the suspension makes you forget about bumps and landings. Add in Yamaha’s reputation for durability, and you have a true “buy it and enjoy it” ride.So if I couldn’t improve on Yamaha’s racer, I figured I’d try to change it…into a Suzuki. Yamahas feel stable to me, but I wanted a bike that could get my heart racing in the turns, even if that also meant occasionally spiking it on the fast straights.I went to Bones at Pro Circuit (www.procircuit.com), who said he could do something with my request. At my insistence, I first tried PC’s 22.5mm-offset triple clamps (25mm is stock) without the recommended suspension revalve. The $599.85 clamps were a step in the right direction. The front end lost a little of that “way out there” feeling and the bike was happier leaning. The front wheel would occasionally threaten to knife under, but the beauty of a light little two-stroke is how easy it is to snap back if it gets out of shape. The non-offset handlebar mounts I selected were a good compromise between the two options the stock clamps offer.Then I got the suspension revalve, and I knew I’d found my racer. Bones put in lighter fork springs, revalved both ends and threw in a few PC trick items like internal kits, a shock anodized kit and national fork spring tubes. A good suspension tuner gives you what you ask for, and Pro Circuit delivered, for $1564. The bike now lays into turns and rides through ruts like a dream. The balance feels perfect and jump takeoffs (the few that I huck) have been drama-free, and all flights have returned me to a normal, upright position. Landings are comfortable to the point I’ll purposefully overjump some small obstacles in the interest of improving lap times. I’m not feeling headshake or any knifing, just a nimble, agile 125.I’m playing with exhaust pipes, but only out of experiment, not necessity. The stock power is smooth, usable and plentiful for tight MX tracks. Bridgestone 403/404 tires are keeping me stuck to the track, and so far the stock drivetrain is showing just a little wear. At 40 hours the bike is holding up perfectly (thanks, Maxima). I’m not a revver, so I’m still on the stock top end. I’ll replace that out of guilt soon enough. Plus, it’ll be fun to have Jimmy walk by and say, “Why are you changing the piston, you never even get the power valve open.”So what do you do once you have your perfect bike that really has no needs? Move to wants, and that means custom graphics. DeCal Works (www.decalworks.com) made some custom radiator shrouds that crack me up and keep with the theme of this bike-fun. Custom shroud kits (and this set for Dirt Rider readers) start at $79.95.Yamaha is continuing to sell the YZ125 into 2010 and hopefully far beyond. If you haven’t ridden a 125 for a while, you might be surprised at how powerful this bike is. If you’ve never ridden one, you’re missing out. And if you’re still in your growing years, don’t be too enamored with the 250Fs you see the pros riding. That’s a whole different world where people get paid to ride. I feel this 125 is the greatest bike for this world.