`04 Rm-Z And Kx-F: the Real Dirt!
`04 RM-Z AND KX-F: THE REAL DIRT!
OUR SOURCES WERE solid! The 2004 Kawasaki KX250F and Suzuki RM-Z250 really are on their way to the U.S. of A. Both bikes should be in dealers by September. Whether it's cloaked in green or yellow plastic, the non-counter balanced, liquid cooled, dohc four-valve Single will be tuned identically. Designed by Suzuki, the 77.0 x 53.6mm powerplant is tiny. Not much bigger than a typical 250cc two-stroke, the semi-dry-sump design locates the crankshaft low in the chassis for im proved handling. Motor oil is stored in the transmission, and is pumped through the en gine via inter nal galleys that simplify the engine's exterior. Neat tricks in clude two-stage ig nition mapping that allows the engine to idle normally when the five-speed transmission is in neutral, then increase idle rpm when a gear is se
lected to help reduce compres sion braking. A narrow 25-de gree included valve angle with 31mm intake ,and25mmexhaust valves-all titanium-make for a compact combustion cham I ber. A 37mm Keihin carburetor with a throt r tie-position sensor and pumper mechanism han. dies fuel delivery. Both bikes share a KX-style steel perimeter frame that is specific to the mini-Thumpers. It is surrounded by KX spec components, such as Kayaba suspension, and
KX wheels and brakes. The shock linkage mirrors that of the two-stroke KXs and RMs, which is similar in design to current Yamaha YZs. Less is known about the forthcoming 450cc versions of these bikes. Developed separately, they are slated for a 2005 release-at the earliest. Word is, the RM-Z450 will have an aluminum frame. Expect a sneak peak at the last round of the Japanese MX series in September. Rumor has it both big-bore engines will see plenty of duty, with off-road, dual-purpose and possibly supermoto applications. Jimmy Lewis
