Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128330
FDUR-STRDKES RM·Z450 Key Features Engi ne: • Compact 45Occ, four-stroke , liquid-cooled. DOCH, fourvalve engine design with emphasi s on broad power delivery. • Narrow cylinder head design featuring shim-under-bucket vatve train w ith titanium valves for reduced reciprocation mass and more stable high-rpm performance, plus 26degree included valve angle for shorter front-to-rear cylinder head length. • Ughtweight hollow -type camshafts with carbu rized surface treatment for durab ility and high lubrication qualities; hollow design further contributes to precise valve operation at all engine rpms. • Forged-aluminum piston with ti n plating and oi l-retaining grooves to reduce friction and wear. • Electro plated aluminum cylinde r. • Keihin FCR40 carburetor with hot start system and th rottle-position sensor linked to digital C DI ignition. • Ughtweightexhaust system with titanium head pipe with largecapacity stainless steel secondary pipe and aluminummuffler. • Automatic decompression system similar to RM-Z25 0. • 5emidry sump lubrication system featur ing separate crankshaft and transmission oil chambers - using the transmission as the oil sump perm its low crankshaft placement for reduced engine height and low center of gravity. • 5uzuki-Active-Vent-5ystem - one-way reed valve system between the crankshaft and transmission to reduce crank chamber pressu re and enhance piston ring seal performance and overall engine power - kick start idler gear doubles as centrifugal blow-by gasloil separator, allowing even more compact engine des ign. • Four-speed transmission for we ight reduction and compact engine size - allows clutch to be placed closer to the engine centerline to concentrate engine mass and reduces crankcase area requ ired for transmission. • Counterblancer shaft gear-driven olf the magneto rotor to reduce engine vibration without adding to engine size or weight. Chassis: • Aluminum twin-spar frame designed for optimal strength , rigidity and weight - construction includes forged steering head. main spars and front engine mount braket; plus extruded rear shock mounts; and extruded and pressed aluminum down tubes . • Aluminum swingarm with tapered beam design similar to RM2S0 - features cast aluminum cross beam to improve straight-line performance. • RM250-type rear suspension linkage - suspension load placed on the swingarrn instead on the frame to reduce weight and allow smoother movement of the rear shock and linkage for improved rear-wheel traction. • Chain guide similar to RM125/250. • Showa-brand cartridge-style front fork with 47mm inner tube . plus 22-way compression dam ping. 20-way rebound dam ping and 12. 1 inches of wheel travel - inner structu re similar to RM250. • Showa- brand rear shock absorber with large 50mm piston and inner 18mm inner rod for increased oil flow and stable damp ing performance - includes 4-way adjustable highspeed compression damping. 16-way low-speed compression dam ping. 19-way rebound damping and 12.2 inches of rear-wheel travel. • Large 250 mm front disc brake designed for reduced weight and high durability - includes Kevlar brake hose for low expansion rate and improved brake lever feel - rotor is mounted at fou r points instead o f six with new-type shoulde red bolts for a secure fit and minimal weight. • 240mm rear disc brake with lightweight caliper body similar to RM-Z2S0 - rotor is mounted at four points instead of six with new-type shouldered bolts for a secure fit and minimal weight . • New-style wheels. spokes and spoke nipples - spokes are bent at a nine degree angle instead of ]0 degrees to reduce stress and increase overall wheel strength. • New front and rear wheel hubs designed for reduced we ight and added strength. RM·Z250 Key Features Engine: • Straighter exhaust ports and extended center rib for intake ports to improve low- to midrange engine response. • Revised ignition timing and revtimiterfor improved high rpm and overrev performance. • New clutch plate design and improved clutch spring material for better clutch action and feel. • Improved throttle valve design and new stainless-steel throttle cable designed for low-frict ion operation. • More durable shot -peened third and fourth transmission gears for improved reliability . • Stronger reinforced airbo x design for increased durability and improved intake sea l. • N ew -designed oil filte r cover for simplified oil change m aintenance - cover can be removed w ithout re m ovi ng wa te r pump and drai ning cool ant . • Larger radiators for increased coo ling capacity and m ore stable engine operating tem pe rature - radiators are 40 mm longer and 17.8 percent larger core area . • M ore durable muffler construction with improved packing. Chassis: • Steering head wall thickness increased from 2.6mm to ] .2mm for increased rigidity and improved handling perform ance . • New low-friction fork oil seals for smoother action thro ughout the fork stroke. • O n-the-fly clutch lever adjuster added to clutch lever perch . • New front brake lever shape for improved rider feel. • Wider handlebar mounting positi on for increased handlebar strength and bending resistance. • Front fork clamp bolt position relocated to left/right sides for easier ma intenance and improved clamping strength. • Ughter weight front fork and shock absorber bolts. • New Teflon outer clutch cable liner for reduced friction and improved clutch operation and feel. • New front brake pad material for improved brake performance and feel. • More durable chain guide roller with two internal bearings.