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/127177
~ T~: 1989 Honda CRI2~RK ~ • Little red rocketshlR By Nate Rauba Photos by Kinney Jones ~- J ust becau se H onda's CRI25 didn 't receive.inverted forks like it's larger "brothers," the CR250 a nd 500, it sho u ldn' t be di scou nte d as Honda's negl ected child. . For th e '89 CR I25 go t its share of im proveme nts too , and th ey a re improvements that mak e it better th an last year's model. The most obvious change is the • swi tch to a low-boy pipe, introduced . on last year's CR 250, and the resulting low er cen ter of gravity. The CR125 also got the new Delta Link Pro Link rear suspension al so introduced o n last year's 250 and en gine improvem ents aimed at making th e CRI25 , easier ' to ride a nd more reliable. Let's get technical In order to broaden last year's peaky powerband Honda changed the port shapes and slightly rai sed all but the intake port. The exha us t port was widen ed by .1mm and Honda's Automatic Torque Amplification Ch amber (ATAC), wh ich has a reshaped chamber for front-tire clearance, is closed off later Tn th e rpm range. The cylinder is now Nikisil-plated for better cooling and quieter operatio n, which al so allows the tension on the piston ring to be reduced. The cylinder head is ma chine finished for co nsistent combustion shape, and combus tio n occu rs one degree later a t all rpm ' du e to new ign ition tim ing. T o improve top-end reliability th e connecting rod 's "s ma ll end" radius has been increased ; resulting in a .5m m jump in bearing width and pis ton width at the rod . The piston a lso has deeper oil retention groov es, th e p iston p in hol e is tin pl ated for du rab ility, and th e pi ston pin has a red uced inner diameter for grea ter rigidity. . The 'B9 CRJ25 takes on the look of the CR250 with its lower pipe and redesigned radiator shrouds. Down below th e " big end" of the connecting rod was increased Imm and the larger bearing has an extra roller and new cage. Near the rod the inner web of the crankshaft has been enlarged and crank weight has been incr eased 100 grams. Both right and left crankcases have been changed to make room for wider seco nd, third and fourt h gears. The increased width of the gears also required a longer mainshaft, co un tershaft: clutch rod and a reshaping of the shift forks . Fuel is fed to the cylinder through a new reed-va lve from the 34m m Keihin carburetor. A 2mm increase in the opening of the reeds increases fuel flow, while wider, longer petals with less gap increases durability. Gases are expelled through the new low-routed exhaust pipe and out a quieter silencer, whi ch allows severa l changes to be made to the chassis in order to lower and cen tralize th e cen ter of gravit y. The fram e has new gusseting at all fram e pipe junctions, and . th e diameter and thickn ess of the steering head pi pe have been redu ced in order to save weight. Steering angle has been increased a degree to 27. . The lower exha ust pipe allows more room for a .3 gallon larger fuel ta nk and an easier-access ai rbox. Inside th e airbox is a ' new filter element, cage and mounting flange (Below left) Sereral changes were made to the engine to broaden tlte powerband and improre reliability. (Below) The low-boy exbaust pipe allows other com"."ents tobelowered, giri.g the CR a lowerCeffter of gravity. It also allows more cool air to reach the shock reservoir. 14