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.