It has been one year since Kawasaki and Suzuki embarked on their first joint project: the mighty 250 four-stroke. Last year's highly anticipated KX-F/RM-Z250 definitely opened some eyes as the bike was a contender in its first year of production. During our 2004 MX shootout (Jan. '04) testers praised the motor, but it wasn't long before the first-year blues became apparent. Problems in the cooling system, with the transmission and clutch and the suspension began to surface as the bikes were made available to the public, and some of the ailments left many scratching their heads. Did the co-op not work? Or did someone try to cut corners somewhere along the line in the bike's development? Whatever the answer, there was no doubt the bike had potential; it just needed some fine-tuning. And that is exactly what the '05 model received. After our initial days of testing on the second-generation KX-F/RM-Z, it was clear the bike got the redesigns it needed.COOL AID
One of the biggest glitches the '04 model had was in its cooling system. If the temperature was hotter than 70 degrees and our test bike was being ridden aggressively, it would lose coolant faster than we could replace it. For '05, the hyperthermia was treated with 40mm-longer radiators, which offer much greater volume and cooling capacity. The water pump was also revised to keep the coolant flowing properly. A side benefit was the water pump cover was separated from the oil-filter cover, so thankfully you no longer have to drain the coolant just to change the oil filter. Now that cooling is less of a headache, the motor runs strong consistently, and none of our testers smelled that warning odor of coolant dripping from the bottom of the bike.As for the motor, it didn't get too many performance updates, which is a good thing since it has some of the best power characteristics of any of the 250 four-strokes. The four-valve cylinder head received some minor changes to enhance overall throttle response. On the track, the motor gives an abundance of confidence. The power hits hard off the bottom, pulls hard through a strong midrange to the top-end and revs out well before hitting the rev-limiter. This personality caters to all skill levels; it is super-rider-friendly as it offers healthy roll-on power with minimal clutch required to get the rpm up.The modifications to the motor gave the new bike a bit more snap, so whether you're just cruising or out hammering motos, it responds. As Kawasaki technicians had come up with some great jetting in stock trim, we merely opted to richen the fuel screw from 1.75 turns out to 2.0. The transmission shifted flawlessly under hard acceleration. Last year's model became known for transmission woes, often losing third gear. The '05 KX-F/RM-Z has a shot-peened third gear for increased durability. Another weak link, the clutch also gained improved-design friction plates, and our clutch didn't show any signs of fading during testing. The clutch cable is now lined with Teflon, easing and lightening the overall pull a bit.A BIT BUMPY
We aren't going to beat around the bush: Some of us really hated the suspension on last year's bike. Unfortunately, other than new low-friction oil seals the '05 didn't receive any revisions to the Kayaba suspension. We were really hoping for some updates. It would have been great to see the bike come with the same Kayaba suspension as on the new Yamahas and the KX250 two-stroke, or the same Showa suspension that comes on the new Suzuki RM250 two-stroke. After spinning numerous laps, we played around with the clickers on the fork, ending up at 10 clicks out on compression compared with the stock 12 clicks out. We stiffened up the fork a bit to soak up big braking bumps but could do very little with high-speed impacts, as the Kayaba is harsh and choppy in fast sections.The fork tends to sit very high in the stroke and is too progressive in fast sections yet not progressive enough in low-speed sections. The shock worked better. We toyed with different ride heights and ended up running the recommended 98-100mm of sag. In rough track conditions we opted to stick with the stock compression settings at 12 clicks out, but we did speed up the rebound 2 clicks. A bit quicker rebound kept the shock from packing through braking bumps. Under hard acceleration the rear tire stays planted and hooked up. For the most part the shock is predictable; it can deflect off square edges and bottom abruptly when landed short or even flat in faster sections but responded well to some of our adjustments.MOLDED FOR MOST
The ergonomics are compact but were approved by all of our test riders. The seat did actually get a small update as the mid-seat height is a tad higher. Its foam is firmer and sits under a new gripper seat cover that is built much better than last year's thin cover. The handlebar mounts are adjustable, allowing you to rotate them forward to get a bit more room. We opted for the forward position as most of our testers felt the small change helped with comfort in the standing position. The footpegs have been widened and shortened for better clearance in ruts. We suffered no troubles from the footpegs packing with mud as with last year's bike, and we also found better grip. A new clutch perch and lever with a handy quick-adjust replaces the 1970s-era assembly and provides smooth action. Overall, the KX-F/RM-Z feels light, nimble and very narrow. All the bodywork is tucked in, and each piece molds with the next, so there is no snagging or hanging up your boots or pants.NEW AND IMPROVED
Although the '05 didn't undergo a myriad of alterations, the ones it got made a world of difference. The '04 enjoyed a bit of a bad rap, especially for durability, but today's competition is a tough and demanding lot. So it comes down to nitpicking. With increased robustness in the transmission and new radiators to keep the motor from overheating, this bike could very well move into contention for a shootout win. The only true holdback could be the unchanged Kayaba suspension. If you're thinking of purchasing a KX-F/RM-Z, you could get the suspension done and make your bike perfect. And if you're a racer, you'll find the contingency for this bike is awesome. Not to mention the trackside service Team Green and Suzuki offer.Opinions
Although the KX-F/RM-Z has been the underdog in its respective class, it's one of my favorites. For me, the motor has more usable power than any of the other bikes in this class, and the power hits harder and carries all the way through the rpm. The ergonomics fit me to a "T," and the bike's maneuverability is effortless. The suspension is not nearly as good as it should be, but who cares? Instead of spending $800 on an exhaust system, you should spend the money on redoing the suspension. With new suspension, this would be the bike I would take to the starting line week in and week out.
Corey Neuer/5'11"/159 lb/IntermediateI was truly impressed with Kawasaki's 2005 KX250F. After I got the suspension dialed in as best as I could, I was amazed at how well the bike handled. I could turn anywhere I wanted and pick any line I wanted. The motor has tons of power. I have been riding big 450s lately, and I have to say the KX-F didn't feel the least bit slow—it has power whenever you need it. I really liked the front brake; it offers a ton of stopping power and never faded on me. I liked the ergonomics with the handlebar mounts forward to get a bit more room, plus that seemed to give a bit more leverage on the handlebar, making it easier for me to pull up on the front end.
Frankie Mecono/5'10"/180 lb/Pro
