Honda Cbr600f4
Honda CBR600F4
Put it all on Red!
NICK IENATSCH
BRILLIANT, I THINK TO MYSELF AS I LAP LAS Vegas Motor Speedway. Incredible turnin, and steering so light that the first lap is accomplished with fingertip ease. As the tires warm, the pace increases until redline shifts are the norm and my knee pucks are giving their all. The free-revving inline-Four flashes down the front straightaway in excess of 140 mph, and slows for the Turn 1 chicane as if deploying several large parachutes. Finally, the checkered flag ends the first session, and I coast into the pits smiling and patting the fuel tank of the bright-red bike. This four-year-old Honda CBR600F3 is so fantastic, I can hardly wait for the second session, when I'll get to ride the new-for-’99 F4. Could it possibly surpass its predecessor?
It’s fitting that Honda chose Las Vegas to introduce its biggest two-wheeled gamble to date. The decision to replace the best-selling F3 risks dominance on the sales floor, popularity with the sporting masses and winning performance at all levels of 600cc roadracing competition.
As tough as it is to replace a legend, though, Honda’s R&D testing and raceteam feedback told the engineers exactly what needed improvement. This was balanced against the requests of the tens of thousands who voted for the CBR600F2 and F3 with their hardearned dollars: “Don’t mess with this great streetbike,” they demanded. And Honda listened. _
Tech-heads will have read the details of the F4’s specs in last month’s issue, so we’ll describe how those changes feel while circulating the racetrack. From the first lap, the F4 struck some familiar chords. I rode my wife’s F2 to the racetrack that morning and the ergonomics felt unchanged. But that’s where the similarities end-the F4 is a case of revolutionary evolution.
From the seat, the changes come at you subtly but distinctly. Though the F4 transitions into medium-speed comers with the same light touch, there’s a bit more roll-in resistance due to the halfinch-wider rear wheel. There’s also significantly more feedback through the handlebars, thanks to the all-new aluminum chassis and improved cartridge fork. The 43mm fork tubes are 2mm larger than last year’s counterparts and are raked more steeply (24 degrees versus 25.5), but have a tad more trail (3.8 inches versus 3.72) due to a change in offset. And glory hallelujah! the fork now wears compression-damping adjusters in addition to rebound damping and spring preload.
Front-end feel is synonymous with confidence, and much of Honda’s efforts went toward improving this facet of handling. The improved fork allows the rider to place the front tire exactly where he wants it, and the superb chassis/tire (Dunlop D207) combination makes this one of the most neutrally balanced bikes to trail-brake.
Rather than simply making the new chassis as strong as possible, the engineers designed in some flex. The triple-clamps, for instance, hold the forks 12mm farther apart this year, but they aren’t the beefy, machined-from-billet pieces we’re accustomed to seeing on racing Superbikes. Likewise, the triple-boxsection swingarm now attaches to the engine cases and frame with a 3mm-larger pivot, but it is unbraced, and measures 22 percent more stiff laterally and 16 percent less stiff torsionally.
Everything being equal, a lighter motorcycle performs better. And Honda’s efforts to drop weight were spearheaded by the new aluminum chassis and bolt-on subframe that trimmed 15.4 pounds while upping lateral and torsional rigidity by 3 and 15 percent, respectively. The engine redesign sliced off another 6.6 pounds, and additional snipping resulted in a total claimed weight reduction of 33 pounds (373 pounds dry versus 406). The engine also contributes to the shorter wheelbase (54.7 inches versus 55.3), as it sits closer to the front wheel. And while you can feel the weight reduction the moment the bike comes off the sidestand, you really appreciate it when getting into and out of comers. On the racetrack, this thing rocks!
All the work Honda poured into the engine and ancillary parts seems aimed at roadracing, however, because there is only the slightest improvement in straight-line performance. Lighter valvetrain pieces and even more oversquare cylinder dimensions (67mm bore/42.5mm stroke) point to higher engine speeds, yet the tachometer remains redlined at 13,500 rpm and the rev-limiter still cuts in at 13,700. Certainly, the F4 revs more quickly and eagerly than the F3, but repeated tests showed the new bike to have only the slightest advantage in acceleration. Interestingly, claimed torque is up only .7 foot-pound to 47.7 ft-lbs. at last year’s 10,500-rpm peak, while claimed horsepower is up 5 bhp to 110 bhp at 12,500 ïpm, 1000 rpm higher than last year’s peak. And while we can’t confirm anything until we get the F4 on the CW dyno, there are spots in the 4000-7000-rpm range where the F3 feels stronger.
Other notable engine mods include an inclined cylinderhead-mating surface that allows beautifully straight 40degree intake ports, fed by all-new Keihin 36.5mm downdraft, flat-slide, CV carburetors. Great stuff, though the F4 retains the line’s slightly abrupt on-throttle transition and minor driveline lash. The bolt-on coils are missing, replaced by stick coils mounted on the sparkplug boots. Also of note is the relocated water pump hiding under the carburetors, which feeds the center of the engine to distribute cool water evenly to all four cylinders. This coolant comes from a 30mm taller curved radiator with 17 percent greater cooling capacity. Yes, the F4 ran cooler on the gauge, but still heated up fairly quickly when run slowly or idled too long.
But even if the F4’s engine performance isn’t light-years ahead of its predecessors, the Supersport race teams running Hondas will be content with the chassis changes, because getting the power to the ground has been the problem with the current bike.
When riding the F3 and F4 back-to-back, the new bike is significantly more comfortable accelerating off comers at deep lean angles, and gives the rider a more precise indication of what’s going on at the rear contact patch. The swingarm is only 2mm shorter, and the shock linkage is the same as last year’s piece, but the combination works well together-we can’t wait to try it with a pair of sticky race tires!
If you’ve ridden an F3, you’ve marveled at how well the brakes work. So have we-considering that these were old-fashioned, two-piston jobs. Well, Honda has finally fit a pair of modem Nissin four-piston calipers up front, with staggered pistons (34mm leading/32mm trailing) working on 296mm, semi-floating rotors. The result is improved feel during threshold braking, whether you’re braking hard enough to bring the back wheel off the ground or exploring the nuances of trail-braking. We didn’t see one journalist overshoot any of the three hard-braking spots at Vegas, and that’s a great testament.
The F4 steps forward in almost every aspect, but several details rankle. First, last-year’s attractive white-faced tachometer has been replaced by a black one on the new, CBR900RR-style, “thin-technology” instrument panel. Second, racers will find it difficult to convert the shifter to race pattern. Third, when you remove the rear-enginemount/swingarm-pivot bolt to pull the engine, you’ll need a pair of stub-axles to secure the swingarm or you won’t be able to roll the chassis anywhere. And last, the European markets get a centerstand that’s not available here due to cost concerns and America’s more sporting use of this type of bike.
Minor annoyances aside, however, there isn’t much to gripe about. Amazingly enough, the F4 will cost just $100 more than the F3’s $7799 price tag. Look closely, and you’ll find the reasons: The bodywork has fewer sections, the clutch cover and ignition cover are now each one-piece, and new casting techniques were utilized to not only improve strength at the steering head, but to save production costs. Three-spoke wheels are cheaper to make than six-spoke units, and items like the F3’s inner fender didn’t survive the model change. It wasn’t enough to design a better F-bike, the engineers had to keep it affordable, as well.
On that first lap, I couldn’t decide whether the F4 was a revolution or an evolution, and that initial impression stayed with me throughout the day. The bodywork certainly breaks free from the all-plastic look of the previous model, teasing the eye with a view of the tidy new frame while retaining the distinct silhouette. The comfy, flat seat now extends farther forward and downward, replacing the bodywork your thighs touched last year. The footpegs utilize aluminum shift and brake pedals with the heim joints located inboard of the heel guards for a cleaner look, the handlebars are more nicely finished where they mount to the fork tubes and the stainless-steel muffler adds a high-tech look to the clean back end. And a pair of NSR500-style ram-air snorkels just below the headlight on the fairing’s outer edges add an aggressiveness previously lacking.
“Aggressiveness” works well in describing the F4. It buzzes a bit more, yet exhibits a sharper, tighter feel with substantially improved traction communication. Yes, it’s still totally comfy, and boasts a number of detail improvements: The toolkit is now accessed with the ignition key rather than a screwdriver; the dash includes a fuel-warning light, digital odometer and two tripmeters; and there’s an oil-level sight glass. But there’s also a seriousness about the new bike that one couldn’t find in the previous, steel-framed models.
Improving on near-perfection ain’t easy. But with the F4, Honda has managed to deliver something that Las Vegas has never seen before: a guaranteed winner. □
