The invitation-only Soboba trail ride is the best-of-the-best, not-to-be-missed chance to ride the finest trails in Southern California. I don't allow anything to risk the fun fix I get from Soboba. It isn't the weekend for a first ride on an unfamiliar bike, but the 2005 KX250F is one of my favorite mounts. In addition to having great power, the KX-F turns like a scalded cat. I'm not great in turns, but the Kawie four-stroke makes me feel as if I am. Soboba has about 100 turns per mile, so while I didn't actually have this bike built with this ride in mind, it couldn't have been more perfect.I'd love to say this project was my idea, but it began when Kawasaki Tech Services wizard Spencer Bloomer asked Editor Jimmy Lewis if we had any Kawasaki-based projects in mind. Lewis replied, "Make a killer off-road KX250F."Bloomer's background includes being a D37 desert expert, Team Green technician and tester of new KX models, so he builds an off-road bike right and fully equipped.The bike already had hlins suspension, so the engine began with a new Muzzy 280cc kit and sixth-gear kit. Few in the dirt world have heard of Rob Muzzy, but his company has a long history of building fast Kawasaki four-strokes-just normally ones with three more cylinders than the KX-F. Its big-bore kit is a painless route to performance since it's a simple bolt-on requiring no machine work. The sixth-gear kit requires splitting the cases, but it keeps all five stock ratios then adds one more. Pro Circuit knows the KX-F valve train well, and it added its bronze valve seats and springs to ensure the engine lived a long life. The seats are more important for '04 models, since Kawie softened the stock seats for '05, but the valve adjustment has stayed perfect on our bike.An 18-inch rear wheel, an IMS tank and (with all the rain California was getting) Dunlop D773 sand and mud tires were in order. We weren't sure where we would test in addition to Soboba, so Bloomer set 'er up with an '04 KX-F stock ignition (the '04 came with lighting coils whereas the '05 doesn't) and lights from Acerbis. The electrical output is small, so the lights help you to be seen more than they help you to see at night. He also installed an enduro computer from ICO Racing. The newest generation not only indicates whether you are late or early but even tells you whether to gas it or slow up for a tie-breaker check. Bloomer plopped in a Rekluse auto-clutch before adding a Pro Moto Billet kickstand and rivet-on exhaust tip/spark arrestor and optional 96-decibel insert. The rivet-on tip is about the cheapest way to make a late-model four-stroke sound- and spark-legal for California, but it makes the most sense for riders who only occasionally need an off-road-legal exhaust system. Since this was planned as a serious full-time off-road bike, we eventually installed the new FMF Q2. It cost more yet provided the performance of the open stock pipe but with sound that equaled or bettered the quiet tip. A smattering of protective parts and hand guards finished off the bike.Since I had no intention of having Soboba be a shakedown ride, I headed for the high desert to try out the bike. Most everything about the 280 was truly impressive. It started easily and had strong power and response, and you could feel that this engine had a bigger bore. The second problem was some stiffness from the hlins MX suspension in rocks and chop. It was easy to go out about 10 clicks from the MX settings on compression and back off the high-speed a little. We fine-tuned that basic setup, but it worked well in the desert. The action remained very well controlled but was plush on sharp-edged impacts. It even handled rocks well. That is pretty amazing for a fork and shock combo that had been rated as highly as the best motocross combos we tested.Finally, the Rekluse clutch was engaging too early. We exchanged as many of the tungsten balls for steel ones as possible and refined the freeplay adjustment of the cable.That made the KX-F ready for the Soboba Indian reservation land, which stays exclusive because riding there will land you in deep hot water except for the one day when Grand Marshal Malcolm Smith leads two awesome loops. Soboba's terrain is steep and ridged with razorbacks and canyons. As with all of SoCal, it can be miserable when dusty, but in '05 we've seen more guys building arks than facing dust.Despite record rainfall, the ride was run in conditions as perfect as possible. We headed right up a shallow river then into sublime traction with sections of mud, but fortunately it's sandy mud. There were a few boggy places to avoid and many ruts to watch for. Sometimes the organizers gave a 20-foot run at steep climbs, but more often hills immediately followed at least a 90-degree turn. Roll on the throttle, and the bike accelerates away smoothly with perfect traction as if you're somebody famous with a clutch lever. Add in the boosted bottom and mid power of the Muzzy engine, and you have big fun up hills. The Rekluse lets a bike act just like a CRF50F when you choose not to pull in the clutch. Chop the throttle and lock up the brakes? No problem; the engine doesn't stall. Rekluse disengaged the clutch when the rpm dropped low enough. The Soboba trail crew runs you down amazingly steep drops, and some rut all the way down. You don't even need to pull in the clutch; just relax that left hand.When the clutch is fully engaged, the clutch lever works normally until about 8000 or 9000 rpm. Then the pressure on the clutch is too great to fully overcome with the lever. You soon learn just how high you can rev the bike before dropping the clutch in a sand turn. Rev too high, and the bike starts to leave before you're ready. Overall, on a technical ride such as Soboba, the auto-clutch saves an enormous amount of energy and eases arm fatigue. In fact, the KX-F was simply a riot. Its super-nimble handling and light weight let it thread easily through the tight canyons. It had all the power needed to tackle deep, soft, abrupt climbs and the control for technical drops. It couldn't have been more fun. My riding companions had a moto KX250F, a YZ250F and a Honda CRF250X, and when we swapped bikes, I was always glad to be back on the Muzzy KX-F. It was easier to ride, more comfortable and better suspended than the YZ250F and the moto KX-F. The CRF250X was more plush, but the 280 felt lighter and better in the whoops and sand and had much more power everywhere in the rpm range.The big concern with any internal motor mod is longevity, so after Soboba we took the KX-F on many other rides, one a survival run complete with ugly waterfall step-ups fronted with sloppy boulders. After that, we got into deep, gooey clay that packed up on tires and everywhere else on the bike. It still runs strong and, aside from a worn-out chain (stock non-O-ring), it's ready for more.When all the rides were over, we loved the D773 tires and the big-bore kit. The stock KX-F is a blast, and with more torque and power, it is simply the bomb! For 80 percent of our riding, the Rekluse is total magic. When the going is extremely sandy, the benefits don't show as much. However, changing back to the normal clutch takes only a few minutes. As much as I like the Rekluse, I'll reserve it for electric-start bikes in the future.For almost all of our riding, the hlins suspension was amazing-and by that we mean with the standard MX settings. When you buy hlins, there are options to have the suspension personalized, and that would have made it better off-road but compromised the moto-ability. At Soboba, the primo traction made for long downhill ridges with severe chop, and the KX-F was hacky there. It was great for all our normal off-road haunts. We could have modified the stock suspension for off-road with good results but doubt we could have the range of the hlins. We also like the do-it-all nature of the KX280F. With just a few clicks and the headlight and sidestand removed, we could be back on the track. The 280 is great for moto, since it lets the bike pull a taller gear out of turns and cuts down on shifting. Plus, it is totally legal in the age group classes. That about wraps up my feelings about the KX280F: legal but so much fun it's hard to believe it is.