Cycle News - Archive Issues - 1990's

the throttle resp on se, the who le motorcycle is mu ch more immediate and communicative. As the pace qu icken s, thi r:gs onl y get better. Turn-in is much light er'and faster than with the old bike - thanks no doubt . to th e lighter wei gh t and steeper rake angle - and feed b ack from the morerigi d front end is excellent. Full lean is a qui ck, confid en t flick away, and turning res ponse is at leas t equal to that of the GSX-R600, the reigning race-track too l of the class. It is no surprise, as the steering geometry and front- tire size of the CBR are now identical to th e GSX-R's . The front tire is now a 120/70ZR17 - the very size supersport racin g tires come in, and, a Honda engineer said, the bik e was designed wi th this in mind from the beginning. The grea ter ground clearance of the new CBR gives you the extra con fid en ce you need to cra nk it over thos e last few d egree s of lea n to ma ximize your corner speed and tigh ten you r line if you start to d rift a little wid e on corner exit. The d iffer ence in the chassis is mos t noticeable, how ever, on the long sweeper lead ing ou t onto th e front stra ight away. This co rner be gins after a tight d ouble-apex left-hand turn taken in secon d gear; then you accel era te all the way through fourth gea r as you head for the abru p t transition onto the bankin g and th e front straigh taw ay . It puts th e cha ssi s under a h eavy , co n stant loa d , and just off lin e th ere are midcorner bumps tha t could easily upset a lesser chas sis. All yo u ge t from the CBR is perfect stability and mu ch bett er feel from the rear of the bik e than the 1998 CBR. Hitting these bumps - or the transition onto the banking for that matter on th e F3 was more like ly to upset the bik e slightly, and the feel from th e old stee l chassis, by com pa rison, is dull and rubbery . But that is a credit to how good the new chassis is, because the old bike was nothing to complai n abou t in those conditions, itself very s table a nd predictable, with a very good level of feed back. Th e Pro -Frame is essentia lly the same des ign as th e VFR800' s pivotl ess fra me , but wi th the swingarm pivotin g in both the engi ne cases and side plates. The sha pe of th ose side plates plays a majo r role in the feel of the cha ssis. As yo u tuc k behind the windscree n / for the run down the long front stra igh taway, the differ en ce in the power produ cti on is a mazing . Top-end throttle resp onse is vivi d, p ow er p ro duction almost 750cc-like, and absolu tely linear . We s howed a rou n d 135 mph o n the speedometer w it h some rev s lef t just before hitting the brakes for the chicane. The new powerp lant is the most oversquare in th e class, and a tremendou s amo un t of eng ineering effort went into making the big bore wo rk, with meticulous attention pai d to combus tion-e ha mb er s ha p e to ens u re qu ick, co m p lete burn of the ai r I fuel mi xture..Th e end re sult is that th e CBR 600F4 h a s the shortes t s tro ke in the 600cc supersport class at 42.5m m. Being so oversquare, it was a su rp rise to see th e 13,500 -rpm redline unch anged from th e p revious generation's longer-strok e eng ine . Horiike-san explains that the character of the p ower has been shifted upward in the rev range more toward upper midran ge and top-end response, and that, bein g a s treet bike, there was no reason to make the eng ine spi n any faster than it d oes. . By th e same token, this b ik e will be raced, and he also said that for racin g, the engine will s p in sa fely to 14,500 rpm. In ou r time on the track, the CBR . p ull ed stro ng ly all the way u ntil it hit the 14,00D-rpm electronic rev limit. (Left) Riding pos ition is virtually identical to the old bike, but the riding experience Is not. And you can even take the seat off with the Ignition key - no tools required to get to the tools. Two item s regarding the powerplan t need co rrectio n fr om ou r First Lo ok story (Issu e #38, Sep tem ber 30), one our fault, the other not. The first is that there is, in fact, no limit to how fast yo u can spin the engi ne in AMA Su perspo rt racing - th e s toc k limit is irreleva n t. We mad e the mistake of referring to a 1997 rulebook that said the stock limi t mu st be main tained . Tha t rule was done away w ith in 1998 - yo u can spin it till she blows if yo u like. The other mistake was that we said th e cylin der-head ma ting su rface was not perpendicular to th e bor e -' it is, though that isn' t w hat we were told in itially. The in take camshaft is se t high er in the cylinder head th an t he ex ha ust ca m - giv ing th e head a wedge shape - so tha t th e in take tract can be as straight as possible. Pow er throu ghout the rev ra nge was very lin ear an d th rottle response from the perfectly jetted carburetors crisp . As it turns out, a large part of the excellen t respon se fr\lm the engi ne is due to the ram-air sys tem, and the "rnidspeed" air reservoirs in corpora ted in to th e main intak es. Hor iike-san sai d that the ra mair sys tem is far more important to making linear power and improvin g thro ttle r esp ons e w ith th e CBR 600 th a n in improving top -end horsep ower. For the track, best perf ormanc e came by kee pin g th e engi ne sp inning a bove 7,000 rpm, thou gh it is very flexible an d feels at least as str ong in the lower midran ge as the old powerplant. The so u nd and feel from the sho rt-stroke engine is very much like the ZX-6R, thou gh not qu ite as smoo th - the CBR has a littl e bit more high-frequ ency vibra tion. Perhaps more than any single compon ent on the F3 that nee ded upd atin g was the two-pisto n brakes. Braking performance and feel have bee n im proved a great deal wi th the new , CBR900RRlik e fo u r- p is ton calipers and 296mm d iscs. Horiik e-san said that the ou tright power is d etermined by the bore sizes of th e master cylinder and pist on diameters, but that a good por tion of feel and th e nature of brakin g response co mes largely from manipulati on of the stiffness of the br aking hose. We' ll take his word for it. Let it su ffice to say that the (Left) The ram-air ducts and downdr aft carbs are obvious on the cutaway. Fuel injection was rejected on cost grounds, but It's no loss - jetting Is perfect . (Above) The remote-re servoir shock has seven-step springpreload adjustment. 100 100 15 10 as 10 80 70 75 70 65 & ~I 45 10 ... :1 3025 20 15 10 ,=,.....,.__= J 4 new brakes are a huge improvement over the o ld two-pis to n d e s ign and d espite havin g grea ter ou tri ght power, th e new CBR was less likely to lift the rear wheel u nd er hea vy br aking loads. Feel at the limi t was excellent and stability fau lt less, inspi r ing enough confidence to let you how l the front tire braking for the infield (esp ecia lly a ft er blowing the brake ma rke r by a mile...), withou t p rim al fear of sudden lock-u p. At the same time, the feel and resp onse a t ligh ter le ver p ressures - adjus ting mid corner speed for ins ta nce - is also g reatly imp rov ed , and lever travel before the pads enga ge is much shor ter . Front-end div e is minimal. Ou tstanding. It may be difficult to make a widely capable bike, but Honda has shown us, once again, it is clearly no t im possible. Our tim e with the CBR600F4 on th e stree t prod uc ed similar revelations to those on the track . Damping at stock settings is spo t-on fo r lig hter riders, and though the rear high -speed com pression damping is on the firm side, the chassis . feel tha t this helps produce is wo rth the minor sacrifice in su pp leness . Suspens ion adjustm ents work over a useful ran ge, allowing me (200 pounds) to find a setting tha t worked well on the track, and anot her for the stree t. The chassis is mor e than just confidence-i ns piring on the street - it's just plain inspiring . It is a chassis tha t w ill accommo date ex perts and beginn ers alike, res po ndi ng equa lly well to fu ll-scratch han gin g off in corners or just plai n sit ting straight up in the saddle. Chassis feel is one 'thing on t h e race tr a ck, but in th e ever-fl uid world of street riding, w here one never kn ow s what lurks around the next ben d, the information yo u can glea n from the contact patches on the F4 is inva lua ble information communicated free ly. Low-e nd power p rod uc tio n hasn't been lar gely sacrificed for the better topend power, and the super-slick shifting at t h e tr a ck - al m ost swi tc h like o n upshifts - translates to su per-slick shifting on th e street, w it h shorte r, morepositive throw s and grea ter preci sion . Clutch feel is extre me ly positive, wit h a distinc t e ngagemen t band a n d quick and smooth response to lever input. 5 ,.,-,.,--.-,.,-...--,.,-- - , 0 5111 .U U 12 U (Left) The torque curve is typical Honda magic - flat and broad. Peak power Is 96 hp, seven more than our 1998 test bike. JA -(lll.-) . T here is n o d oubt that the 1999 C BR600F4 ·r e p re s e n t s a m ea sured improvem ent over the mod el it replaces. In that regar d it is much like the 1998 CBR900RR: better in every way in every kind of rid in g. On e can only hop e, for Ho nda 's sa ke, that in its difficult pursuit of a balanced motorcycle, enough of the "R" character w as let throu gh to be able to stand up to a certain all-new Yama ha - on the track and in the showroom. Let the battle begin, and to the customer go (~ the spoils. Specifications 1999 Honda CBR600F4 Engine . .Uqui d-coo led in-line four-cylinder w/DO HC and four valves per cylinder II stroke 67 x 42 .5mm .Dis plece me nt . _. . . . . . . . . . . .599cc ,pompression ratio 12.0:1 Carburetion (4) 36 .5mm flat-slide CV Ignition . _ Compu ter-controlled digital . transistorized wI 3-D map Tran smis s io n Close-ratio 6·speed ,Fina l d rive #52 5 O-ring chain F Pro -Frame tw in-spar alurninUrfl ......./trail 24· /96mm W lbase 54.7in Seat height 31.91 Bore Suspension ;,Front ... . .43m m HM AS cartridge f wi spring preload and rebound- and c pression-dampinq adjustment: 4 _ in. tr 7 Rear . ... .Pro -Link HMAS single s 'w l spring pr eload and rebound- and pression dampin g adjustme nt: 4 .7 in. Brakes Front 'fIear Dual 296 mm floating wI four-piston Single 220m wI single-piston ,....., ,..... ~ Q) "S Q) :> o Z 27

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