Cycle News - Archive Issues - 1990's

The s ix-speed gearbox featu res the same compact design as the R1 's , so the shih linkage passes through the frame, up to the se lector shah. 1999Y amaha YZF·R6 Specifications A gauge package s imilar to the R1's is used and as such featu res the fuel trip meter that automatically resets to zero when you hit reserve. Engine Type Liquid-cooled. DOHC m-hne four-cyhnder w /four valve s per cylinder A lightweight aluminum silence r is used . The void between the Rl-Ilke head lamps Is the ram-air inlet - a first on a Yamaha street bike. Another first for Yamaha Is the use of sp arkp lug-top ignition co ils. see ca rried over fro m th e Rl was th e same basic bra king system. Similar but li gh ter fou r-pi st on ca lipe rs - w it h 298mm d iscs - are u sed a t the fr ont, thou gh a differ ent pad material is specified . The performance of these on the Rl wa s s u pe r b, a n d th e ir fi t men t to a lighter, less powerful motorcycle sh ould yiel d even more eye-pop pi ng p erformance. At the rear, a 220rnrn single d isc - 25mm s ma ller in d ia meter th an the YZF600's - with a tw o-p iston caliper is used . Lik e th e fram e, the 65.5 x 44 .5mm 599cc fou r-val ve-p er-cy lind er powerp lant tru ly is a small versi on of the 998cc Rl engine, save for the fact that it is ra m -a ir - indu ct e d . T he 12 0 h p claimed by Yama ha for the R6 is rath er a u s e f ul increa se over th e 94.6 it clai me d for the YZF600 and could on ly b e a c hieved b y a co mp le te ly n ew d es ign . T he YZF6 00 had the longest st ro ke in it s class by a good ma rgin ; the R6' s stro ke is now the same as the GSX-R600's, with only the ZX-6R's cu rrently sh or te r . With a rev ce ili ng of 15,500 rpm (pa rtly mad e p ossibl e by th e u se of a new val ve-s pring mat eri- . al), peak power un d er standably comes at a loft y 13,000 rpm. To acco m mo d a te the need to pump more air, 'the carbure tors (w it h float-bow l pressure co m- p en sation for th e ram ai r) h a ve had the ir di am eter in crea sed to 37m m . Intake p orts a re nearly vertica l a nd offe r a stra igh t shot into th e co mb us tio n ch amber, w it h the va lv e gui des reliev ed to ma ximi ze flow. Most rad ical of all - and necess ary for the en gine speed - is the cam timing: Valv e overlap fo r th e Imm -larger val v es is 75 d e gre e s, dura ti on 292 d egree s for in take and 280 for exhau st. Last year' s YZF - admittedly the most street-orie n ted of th e four we includ ed in ou r Las Vegas 600cc Shootout - had a valv e overlap of just 58 degrees and a duration of 268 for both intake and exhaust. Expect a higher-than-normal id le on the ·R6 as a result of the rad ical timing. With power output up as mu ch as it is, a larger radia tor and oil p ump were used on the R6. Concep t car ryov ers from th e R1 inclu de one-piece cylinder I crankcas es, carburiz ed connecting rod s for the lar ger- ma in, five- bea ring crankshaft, a nd cera mic composite coating for the cylinders. The cams are driven 'from the right side of th e engine , benefiting both the size (more com pac t) and cooling (more even temper ature betw een cylinders) of the powerplant. Oneof the items not used for the R6 was th e five valves per cylinder of the The truss-type swinga rm is similar to the one used on the R1 , and is longer by 2.5 inches than the one used on the old YZF. Rl. Yamaha used. four valves per cylinder because the ben efits of having five valves only co me in to p lay on engines w ith a larg er bore th an th e 65 .5 m m found on the R6. You' ll also notice that th e EXUP ex ha u st-va lve system is n' t foun d on the R6, either. This is becau se EXUP is most effective in the low er rpm ra nge, and the R6, spinning as fast as it d oes, sim ply wouldn't ben efit from the extra weight or complication of the system . With p ower ou tput su ch as it is, a "750cc ca pacity" clu tch is u sed on the R6 that is 14mm larger in diamete r than th e YZF600's . In addition, the primary drive ratio has the clutch tu rn ing slower in relation to engine speed than on the YZF600, and we can only hope that this unit wo rks bet ter on th is bike than the one on the old 600. There are no shared par ts between them . Yamaha had no official com men t as to when the R6 would be comi ng to the U .S . m a rket. Th e o ri g ina l YZ F600 (w h ich Yamaha says will co n tin ue in productio n co nc u rre ntly w it h the R6) w as ava ilab le in Eu rope for a whole mod e l year befo re it hit d e al ers in the sta tes, though Yam aha didn't wait that lon g with the more recen t Rl. We can only hope it's coming to a race track C 1\' - and dealer - near yo u. And soo n. Displacement Bore x stroke Compression ratio Maximum power Maximum torque Lubrication 599cc 65.5 x 44.5mm '. .12.4:1 120 hp @ 13.000rpm 50.2 ft.-/b. @ 11 .500rpm W et sump Carburetion . .Keihin CVRD37 with TPS Primary reduction ratio 86/44 <1 .955) Secondary reduction ratio .. .45/ 15 (3.000l Clutch Wet. multiple disc Transmission . .Constant-mesh6-speed Ge ar ratio 1st 37113 (2.846) Ge a r ratio 2nd 37/ 19 <1 .947) Ge a r ratio 3 rd 28/18 (1 .556) 32124 (1.333) Ge a r ratio 4th . _ Ge ar ratio 5th 25/ 21 (1.1 90) Ge a r ratio 6th 26/24 (1.083) Fina l drive Chain Generator AC magneto Chassis Overall length Overall width Overall he ight Seat height Wheelbase 79.7 in. 27.2 in. 43.5 in. 32.3 in. 54.3 in. Minimum ground clearance . .5.3 in . Dry weight Frame type Rake/trail Fuel capacity 372 lb. Aluminum Deltabox II 24°/81 mm .4.5 gal. Suspension Front Fullyadjustable Kayaba 43mm co nventional telescopic forks wi 5.1 in. travel Rear . . .Truss-type aluminum swi ngarm M onocross sys tem wi single fully adjustable Soqui shock and 4.7 in. travel Brakes Front Rear D ual 295mmdiscs with four-piston calipers Single 220mm disc with two-piston caliper Wh_ls/tires Front 120/60ZR 17 radial on 3.50-in.-wide cast-aluminum wheel Rear 180/55ZR17 radial on 5 .50-in . ~wide cast-aluminum wheel 7

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