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/127962
winn ing perce n tage going . Hence, the d evelopme n t of th e F4, a b ike tha t w as d e s ig n ed to try to r e ta in .th e C BR's c h a racte ri s t ic s tr e e ta b ility w h il e u p pin g t h e ra ce trac k - pe r fo rma nce ante cons idera bly. As spee ds h a v e risen' in th e AMA's 600cc class, so ha ve diffi u lties keep in g th e CBR at the fro nt of the pack - pa rticu larl y after Du n lo p introd uced the new 0 207 GP su pers po rt ti re . T h e in crea s ed grip drop p ed la p times on some tracks by ro ug hly a second and a half over the D364-shod bikes, bu t front-end cha tter problems becam e a serious issu e. En ter a n all -new aluminu m cha ssis a nd beefed -up s us pens io n. Th e ne w chassis features a more aggr essiv e rake of 24 d egrees (F3 was 25.2), co u p led with a slightly longer trail of 96m m (up (Above) Undressed, the new ram-air system's NSR-like intakes are evident, as is the all-aluminum chassis, rear subf rame and swingarm . (Top left) In F4 guise, the CBR600finally gets an aluminum frame. It is 15.4 pounds lighter · while being more rigid - than the steel unit It replaces. (Left) The all-new short-stroke powerplant is said to produce 110 hp at the crank, an Increase of 5 percent. (Leftand above) In a visual res pect, the 1999 CBR11 OOXX is virtually Identical to the '9.8 model save for the gold-colored en gine covers used this year. Underneath the skin, it's a different story. A 3-0mapped electronic ignition and fuelinjection system have been adopted, and coupled with a ram-air system, midrange power is up by a whopping 10 percent, and pea k power by 5 percent , all with improved fuel eco nomy. Low-s peed damping rates have been s oftened by 10 percent for a more plush ride. Cush-d rlve blocks were hardened to help reduce drivellne las h, and revis ed Linked Braking System settings bring it closer to the spec of the excelle nt VFR800's LBS. The new CBR1100XX should be in deale rs' s howrooms by February. 1999Honda CBR600F4 Specifications Engine . .liquid-cooled in-line four-cylinder wi DOHC and four valves per cylinder Bore x stroke 67 x 42.5mm Displacement 59gcc Compression ratio 12.0:1 Carburetion (4) 36.5mm flat-slide CV Ignition Computer-controlled digital transistorized wi 3-D map Transmission Close-ratio 6-speed Final drive #525 O-ring chain Frame ... .Pro-Frame twin-spar aluminum Rakeltrall . . .. ,. " .. " .. ,24°/ g6mm Wheelbase , ., , . , , , .... ,54,7 in, Seat height .. . , . ' ' ,,,.. _ 31.9 in. Suspension Front , .. ; 43mm HMAS cartridge fork wi spring preload and reboundand'compress ion-damping adjustment; 4.7-in, travel Rear . , .. Pro-Unk HMAS single shock wi spring preload and reboundand compression-damping adjustment: 4,7-in, travel Brakes Front , . . , . .Dual 296mm floating discs wi four-piston calipers Rear , , . , , , . , . . , . , .single 220mm disc wi single-piston caliper Wheelsltires Front ' . . : .Three-spoke cast-aluminum 3.50-in,-wide rim w /1 20/70Z R1 7 Dunlop 0 207 radial Rear . .. , ..Three-spoke cast-aluminum 5.50-in,-wide rim w i 180/ 55ZR17 Dunlop 0 207 radial Fuel capacity , ,..' .., .4.5 gal. ,.' ,, ,372.6 Ib, Dry weight 2mm). Ra ke and tra il are now identical to those of the GSX-R600, thou gh at 54.7 inches, the Hond a's wheelbase is .2 of a n inch longer th an th e Su zuki' s. The ne w, mo re rigid frame is 15.4 pounds lighter th a n the old s teel one, a nd as such re p resents a good portion o f the F4's dram a tic weight loss of 37 pou nd s over the F3 mod el. Dry we ight is 372.4 pou nds. Honda ditched the old 41mm-di am eter fo rk in favor of a full y adj us table 43 mm HMAS co nve ntio nal cartridge un it, as well as increasin g the span of th e tr ipl e clam ps by 12mm, a ll fo r grea ter rigidity. At t h e rea r, in w h at Ho nd a h a s dubb ed Pro-Fra me , an a lu mi num swinga rm is located bo th in the cha ssis downtubes and rear of the engine - an Rvlike move, consid eri n g th e fact th at both the VTRI000F an d VFR800Fl.have " p ivo tless" ch as sis, th ei r swinga rms mount ed only to the rear of the engi ne . The Pr o-Frame co ncep t was ado p te d because Of im proved stability and feed back. The remote-reservoir, HMAS rea r shock wo rks in a rising- ra te linkage and is fully ad justable. Lighter br akes grace th e front (on e · Iess spoke on the d isc carrier) and new four- piston calipers bring you to a halt, replacing th e two-p ist on units of old . The rear d isc is 220m m and uses a single-piston caliper. NSR500-like ai r in takes po ke out of the fro nt of the F4, an d feed a two-stage ra m-air sys tem (w ith float-bow l p ressure co m pensa tio n for better th rottle respon se) th a t featu res an 18-p ercentla rger ai rbox for the lighter, 36.5mmbo re carburetors. Red line is set at 13,500 rpm. Wit h th e s hortest stroke in th e cla ss, it is inter esti ng to not e th a t the red line on the F4 is "o nly" 13,500 rpm (the ZX-6R - form er short-stroke king of the class - redlines at 14,000 and the R6 redlines a t 15,500 ). Wit h rules in the AMA Supers po rt class dictatin g tha t the s t oc k re v -li miti n g d evice must be retaine d , one wonders w ha t th e electron ic rev limi t is. In an effort to keep the in tak e tracts as straight as possible, the cylinder- head ma ti ng su rf ace is incli ne d slig h tly in relation to the bor e. Th e sa me ceramiccom posite cylind er sleeves w e've seen u s ed on th e CB R900RR a n d VFR 800 engines are now in use on the ' F4, as is the LUB-coat piston coating that red uces friction. Plug-top ignition coils are used , both for their weigh t benefit an d better spa rk for the 3-D-ma pped ignitio n. The cooling system has been revised to d ou - ' ble the flow rate, and radi at or capaci ty has been increased 17 per cent. Weight savings from lighter eng ine com ponen ts abou n d , w it h a lighter AC gen era to r, sta rter, oil cooler and clutch a ll d oin g their pa rt. Honda d id n't wa nt to alter the cha racter of the p ow er d elivery too much, and represen tatives said that the pow er curve is similar to tha t of the old bike, wit h slightl y less power in the low end and low er mi drange, bu t wit h more power in the upper mid ra ng e and top end. Peak power is claime d to be 110 hp , a t th e crank, an in crease of 5 p ercen t over th e old model. With a d ifferent power cu rv e come different ra tios for the six-sp eed gearbox. Retail price for the F4 has ye t to be released, though it sho uld be in d ealers' sho w rooms by Ja nuary, in eit her redand- b la ck o r ye llow-a n d -b la ck co lo r .schemes . fX 17