Suzuki's Aluminum Cre-Beater!

SUZUKI'S ALUMINUM CRE-BEATER!

Suzuki's much-anticipated entry into the big-bore four-stroke motocross wars has finally broken cover. The all-new 2005 RM-Z450 was designed, developed and produced entirely by Suzuki (no "green" influence). Most notably, the twin-spar aluminum frame (using Showa suspension) has seen significant design variation and now combines welded forgings, extrusions and stampings, á la the GSX-R sportbikes. Few details about the new engine have been released. The carbureted, oversquare, 95.5 × 62.8mm, dohc four-valver uses a narrow 26-degree included valve angle for compactness. Lightweight hollow cams actuate shim-under-bucket tappets and titanium valves, while the crank is carried unusually low in the engine, utilizing the transmission chamber to store oil, for a semi-dry-sump setup. The four-speed gearbox is a weight-reduction measure, shafts stacked near-vertical to keep it short. A counter balancer is gear-driven off the magneto, and placed more rearward than typical. All indicators say this Thumper is very Suzuki-lightweight and flickable. It's been spotted stateside testing at several SoCal tracks, and at the front of the pack at Jap anese Nationals. For price, weight and a full test, you (and I) will just have to wait a while longer. But if the RM-Z harnesses any of the juju that the RM250 two-stroke has this year, watch out.

Jimmy Lewis