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/126921
·VZl25/250/490 VARIABLE DAMPER --'PrinlI ension ' changes. P.q,onlng - -~ @FOAKR.UYEXTEI\IlE) eo-.I_ whIle t e .. Damping characteristics © t o ~ >1. @ il ~ .....---JL-.. lG --' Stroke- The diagram shows how the Variable Damper system worbin the YZ125/250 and 490 forks. As the fork compresses. damping rate increaSes. New flilres: First 10011 at the I987 Yamaha YZs By Kit Palmer Yamaha's 1987 line of YZ motocrossers feature refin~mentsand across-the-board engine and suspension performance improvements, according to company spokesmen. Externally, new motocrossers feature I' h no re~o uuonary c anges or surpnses; other than new handlebar grips and new sty]- ing, suc~ as ~hite radiator shrouds and whlte-paJ.nted frames, the YZs look identical to last year's machines. Most of the modifications are internal. Starting with the smallest displace- Yamaha YZ80T 18 Engine type ....•. Uquid-cooled. reed-valve. two-stroka single 80re x stroke .... 48.0 x 46.6mm Displacement .........•. 82.5cc Compression ratio 8.6:1 Carburator 26mm Mikuni Hor18po_r N/A Torque N/A starting system Primary kick Ignition COl Lubrication . . . . . . . . . . . .. Premix Primary drive Straight-cut gear .Final drive #520 chllin Gear ratios Primary 65/18; 3.611 Final. ......•• 46/14; 3.286:1 6th 26/23; 1.130:1 5th 27/22; 1.227:1 4th 22/16; 1.376:1 3rd 31/19; 1.631:1 2nd 33/16; 2.062:1 1st 36/13; 2.769:1 Frame Single downtube split double cradle 26° .Rake Trail 3.16 in. ment YZ in the line up, the YZ80 has more low- to mid-range power and better throttle response, thanks to poningchanges, (inclu,dingreshaped exhaust ports and port timingalterations), a new reed-valve assembly with square-end reeds, a larger air cleaner, a retuned carburetor, a new exhaust pipe, and a thicker cylinder and piston crown to help reduce heat distortion. ' The YZ80 has a reinforced seat to accept more weight, beefier footpegs, a slightly longer shiftlever and a larger and stronger return spring on the brake pedal. The front disc brake has new brake pads made out of different material for stronger stops to enhance stoppi ng power. The rear SRock has valving changes and a stiffer spring, the chain guide is now aluminum instead of steel and the side covers are now one piece. Much effort went into improving the YZ125T's torque and engine performance at low rpm. The cylinder has reshaped pons and modifications to the YPVS valve; the crankcase intake passage and the expansion chamber are new; and, to simplify repacking, the silencer end plate is Yamaha YZ125T Front suspension type ..... Telescopic fork Fork tube diameter N/A Front wheel travel. . . . . . .. 10 in. Rear suspension type . . .. Singleshock swingarm Rear wheel travel 10.2 in. Front brake 130mm disc Rear brake Drum Front wheel 17 in. Rear wheel. . . . . . . . . . . . .. 14 in. Front tire .•........ 7D/1oox17 Bridgestone Reartire .•......... 90/1OOx14 Bridgestone Claimed dry weight. . . .. 135 Ibs. Overall length 70.7 in. Overall width 30.1 in. Overall height 41.7 in. 48.6 in.. Wheelbase Fuel capacity 1.32 gal. Ground clearance 11.4 in. Seat height 31.5 in. Colon ' ,White Retail price .. . . .. . .. .. . N/ A Engine type ....•. Uquid-eooled. reed-valve, two-stroke single 56.0 x 60.Omm Bora x stroke Displacement 123cc Compression ratio 10.5:1 Carburetor 34mm Miktlni Horsepower N/A Torque ...•..........•••. N/A Starting system Primary kick Ignition COl Lubrication . . . . . . . . . . . .. Premix Straight-cut gear , Primary drive Final drive #520 chain Gear ratios Primary 60/18; 3.333 Final. 60/13; 3.846 6th 25/23; 1.086:1 _ 5th 26/22; 1.181:1 4th .......•.. 20/16; 1.333:1 3rd 24/15; 1.600:1 2nd 26/13; 2.000:1 . 1st 31/12; 2.583:1 Frame .. . . . . .. Single downtube. split double cradle ~ . . . . . . . . .. 27.5° Rake Trail , ...•. 4.63 in. Front suspension type ..... Telescopic fork Fork tube diameter 43mm Front wheel travel 12 in. Rear suspension type Single shock swingarm Rear WMeI travel .•..... 12.4 in. Front brakes •....... 220mm disc Rear brakes Drum Front wheel 1.6Ox21 in. Rear wheel 1.86x18 in. Front tire " 80/1OOx21 8ridgestone M22 Rear tire 100/100x18 Bridgestone M23 Claimed dry _ight. . . .. 192 Ibs. Overall length 84.1 in. Overall width 33.5 in. Overall height 48.8 in. Wheelbase ' 57.1 in. 1 .98 gal. Fuel capacity Ground clearance 13.8 in. 36.8 in. Seat height Colon. . . . . . . . . . . . . . .. White Retail price N/A