Superbiker Revival
SUPERBIKER REVIVAL
CW PROJECT
From Peoria TT to parking-lot GP
DON CANET
THAT'S IT! IF I SEE ONE MORE photo of some Euro moto-maniac sliding a dirtbike foot down through a paved corner with the back end hung out, I'm going to...well, lose my grip. What's a guy have to do to get in on the action, _ give up his American citizenship?
Supermotard is proof positive that sometimes grass does grow greener on the other side of the pond. Ironically, supermotard originated right in our own backyard as a form of racing invented for television. Throughout the early '80s, ABC's "Wide World of Sports" Superbikers event pitted
on a course incorporating paved and dirt sections. California's Carlsbad Raceway hosted the annual event until ABC pulled the plug in 1986. But while Superbikers may be gone, it's far from dead. Racing of this type is thriving throughout Europe.
Maybe it's time we brought it home.
Back when I was still a tricyclin' tyke, little more than a change of handlebars and tires transformed a motorcycle from roadrace to dirt-track, scrambles or desert-racing duty. CWs plan was to build a modern-day multi-role racer. KTM's Duke and my own Kawasaki KX80 mini roadracer (see "The KX Caper," CW, December, 1994) had hooked me on roosting pavement with dirt-derived hardware; now I was looking for a bigger, supermotard-style fix.
Using a 1995 Honda CR500 as the basis for our project, we enlisted White Brothers, a Southern California company specializing in high performance off-road and streetbike accessories, to handle bike preparation. Basic chassis setup involved suspension mods, different tires and rims, and a stronger front brake. Without much of a road map to follow, we hoped to get our bike in the ballpark, then refine the package through ongoing track testing.
With more than 12 inches of suspension travel in stock form, lowering and firming up the CR was the first task. Aluminum spacers inside the cartridge of each fork leg gave a 2-inch reduction in front ride height.
Call It a Superbiker, a Supermotard or simply a modem-day multi-role racer, hybrids like CWs Project CR500 deliver more bang for the buck than a bundle of dynamite. Our CR's wheelie antics carried over to dragstrip testing, too. Launching In second gear produced a best pass of 11.51 econdsat 113 mph, squashing our KTM SuperDuke project bike by more than a full second.
Likewise, a 1inch spacer fit onto the shock shaft between the piston and the top-out bumper shaved 2 inches from the rear ride height due to the 2:1 leverage ratio of the CR' s Pro Link rear suspension. Stiffer springs were installed front and rear, which in turn called for an increase in rebound damping. Since our damping requirements were beyond the range of the stock external adjusters, White Brothers altered the internal valving, too.
With roadrace and dirt-track competition in mind, the knobby-clad stock wheels were swapped for wide, 17-inch hoops. Up front, Kosman Specialties (55 Oak St., San Francisco, CA 94102; 415/861-4262) modified one of its 3.5inch-wide Akront rims (normally used with a billet three-spoke bolt-in center) for our wire spoked-wheel application. The rear wheel required Kosman's cutand-weld process to narrow a 5.5-inch rim down to the 4.25-inch width we specified. Buchanan's Frame Shop then drilled and laced the rims to Talon goldanodized billet aluminum hubs. Seeing a potential market for such dirt-to-street conversions, White Brothers now offers off-the-rack aluminum supermotard rims in the sizes used on our CR.
A lack of clearance between the tire and drive chain became evident once the rear wheel and tire had been mounted on the bike. Placing .25-inch shims behind the sprockets and relacing the rear rim slightly offset to the right solved the problem.
A White Bothers Supermotard brake kit was installed up front for increased stopping power and fade resistance under roadrace conditions. The kit uses a Braking 12.6-inch stainless-steel rotor floating on a White Brothers aluminum carrier. Because rotor diameter was increased over stock, a billet hanger now relocates the standard caliper. An oversized Braking rotor kit was also installed at the rear for improved brake performance in the dirt-track role.
The CR arrived at White Brothers equipped with a Pro Circuit pipe and mild cylinder porting done by American Honda. The pipe was swapped for an FMF Fat Boy, which concentrates more power in the upper end of the rev range. White Brothers also replaced the stock transmission with an IMS wide-ratio gearset. Popular with desert racers, the taller IMS upper gear ratios gave our CR increased top-speed potential. Even the plastic radiator shrouds and front fender got trimmed back to reduce drag, and a narrowed AFAM Superbike-bend handlebar was mounted.
Michelin 250cc GP roadrace slicks were fitted for our inaugural test session at the Streets of Willow road course. The chassis setup was in the ballpark, but somewhere out in left field. Too soft in the rear and overly harsh up front, the CR exhibited a pronounced chatter at both ends when pushed even moderately hard in comers.
White Brothers decided to increase compression damping on the internal shock valving to help reduce squat in corners. The fork, on the other hand, was left unchanged, in the hope that more break-in might eliminate some of the stiction we were encountering. A Scotts steering damper was also installed to quell a mild headshake we experienced while driving off bumpy corners.
Our next outing was something entirely different. Wearing Michelin roadrace rain tires, the bike was given its first off-road test. The plan called for three-time AMA Grand National dirt-
track champ Ricky Graham to race the CJF/CR500 in the Pikes Peak Hillclimb and then the Peoria TT. Within a dozen laps around a small dirt oval near his Salinas, California, home, Graham was enthused about our setup: "I think I can win the hillclimb with it, and the jump at Peoria will be much easier than with a dirt-track frame," he proclaimed.
Back at White Brothers, Graham's short list of modifications was attended to. The steering stops got trimmed back to increase steering lock for dirttrack use. Next, a full-width Superbike bar for additional leverage. The CR's quick-action twistgrip was given an additional quarter-turn to improve throttle control. The left footpeg was sheathed in rubber to provide grip for Graham's steel shoe.
Unfortunately, our assault on Pikes Peak never came together, so we set sights on Peoria as the racing debut for the CJJ7CR500. Although Michelin rain tires work quite well in the dirt, AMA 600cc-class dirt-track rules specify that 18or 19-inch wheels, measuring no more than 3.5-inches in width, must be used. We had Buchanan's lace a set of 19 x 2.75-inch Sun alloy rims to the stock CR hubs. Mounting a pair of Goodyear CD-5 dirt-track tires and Class-C-legal numberplates completed preparation for our foray into Grand National competition.
As fate would have it, Graham broke his left shoulder at the Oklahoma City Half-Mile one week prior to the TT and wasn't fit to ride. He did, however, put us in contact with Mickey Fay, a former factory Honda rider with five national TT wins to his credit. Even for a TT specialist of Fay's caliber, though, racing our bike sight-unseen would be a tall task.
Unlike years past, TT racing has become a bit of a rarity in the Grand National Championship. And with the top Pros getting less air-time than ever before, we hoped that Peoria's infamous jump would play into our hands. The CR has nearly twice the suspension travel of a typical TT bike.
Of 68 bikes vying for a berth in the 18rider main event, ours was the only two-
stroke in the house. The question on everyone's mind was whether Fay could keep the rear tire hooked-up well enough off the comers to hang with the predominant 600cc Rotax-powered machines.
With the help of USC Racing's Johnny Goad (Graham's crew chief) we busted tail during the 60-minute practice, sorting out gearing, jetting and suspension to suit the rough-andtumble Peoria track. Our single biggest gain came when Goad bolted on a dirttrack handlebar, as Fay is more accustomed to a wider, higher bar.
Many in the pits bet against us making the main, but Fay silenced the doubters as he slipped under Steve Morehead on the final lap during the first round of heats. Fay's pass moved our CR into third place and earned a transfer into the main. Underscoring Fay's achievement was the fact that a two-stroke hadn't made it into a Grand National main in 12 years.
As the mid-day sun turned the track dry and slick, though, Fay realized his chances for a top-10 placing in the final had evaporated. After running as high as 11th early on, the CR7CR500 did the slip ‘n' slide shuffle back to 15th by the end of the race.
Still, not a bad debut. With more development, the CR looked to be a viable TT mount. Fitting a larger bore round-slide carb, Fay suggested, would smooth the engine's power delivery while giving it a bit more top-end pull. He also pointed out that other twostroke dirt-trackers he's raced have been equipped with compression releases to produce engine braking useful for backing into comers. We've got one on order.
Having stirred some dust at Peoria, it was time for Project CR to lay rubber on the pavement. I loaded the CW van and headed to Steamboat Springs, Colorado, where each September the network of streets at the base of the ski resort is transformed into a temporary 2.2-mile, 10-turn road course. With plenty of tight turns and rough pavement, the Steamboat track seemed ideally suited to our CR. Colorado's Motorcycle Racing Association even has a class called Formula Colorado, in which converted motocross and dirt-track bikes have been ripping up the Rocky Mountain asphalt since the mid-'70s.
After mounting Michelin Hi-Sport radials on the 17-inch wheels and a stiffer 8.4kg/m shock spring to firm up the rear, I arrived at Steamboat to dis cover wheel chatter was still a prob lem. Several suspension adjustments were made throughout the weekend, but the skitter-and-hop handling quirk persisted. The front brake also became a concern as it overheated and devel oped a spongy feel within a few hard laps. Despite the shortcomings, I man aged to win the Formula Colorado race and finished second to a CR500 ridden by local hero Jim Forington in
the two-stroke Sound of Singles race. Following Steam boat, another test ses sion was scheduled for the Streets of Willow. This time, White Brothers sent R&D head Gary Jones along to observe the chassis problem first-hand. Gary enlisted the aid of his brother DeWayne, a suspension specialist with years of experience tuning Ohlins units for the likes of roadracers Scott Russell and Luca Cadalora. Having witnessed our handling woes, DeWayne resolved
to have the suspension working cor rectly for the upcoming roadrace at Del Mar County Fairgrounds.
New fork springs with a 25 percent softer rate were installed along with a set of Tru-Tech fork caps offering a 15mm range of preload adjustment. Since roadracing produces roughly half the stroke velocity encountered in a typical motocross application, roadrace-type shim stacks were fitted to the CR's fork and shock, giving much greater damping force than what we had been using. Meanwhile, Gary mas saged the cylinder porting and installed a thicker base gasket to reduce com pression and slightly raise the ports for extended revs on top.
Del Mar's temporary parking-lot track was even tighter and bumpier than what I encountered in Colorado. Putting the reworked suspension to good use, I won the Sound of Singles and King of Del Mar races along with setting the fastest lap of the day. Although the fork still proved to be a bit over-sprung, the chatter problem had been greatly reduced. Located at sea level, Del Mar's dense air agreed with Gary's motor work as the Honda stood on its rear wheel driv ing out of corners. A change to keviar-based Galfer pads greatly improved the front brake's feel and eliminated the fade we had previous ly encountered.
This project has been a learning experience all along, and continues to be. Future plans call for further sus pension development and implement ing the feedback we've received from Graham and Fay. For 1997, I'll keep busy converting our multi-role racer back and forth from roadracer to dirt tracker. Pikes Peak still looms large on our list and a return to Peoria and Del Mar would only seem proper.
And if Superbikers racing does make a return to the U.S., you can bet your knobbies Team CW will be in on the action.
SUPPLIERS
A & A RACING SERVICE
933 American St.
San Carlos, CA 94070
800/55 1-7755
Goodyear Eagle DT11
Front 27.0X7.0-19: $110
Rear 27.5 x 7.5-19: $114
bUCHANAN'S
629 E. Garvey Ave.
Monterey Park, CA 91755
818/280-4003
Sun rim 2.75 x 19: $99 each
Front spokes and nipples: $30
Rear spokes and nipples: $32
Drill, lace and true: $52 each
DEWAYNE JONES
PERFORMANCE SUSPENSION
351 E. Bonita
Pomona, CA 91767
909/626-2751
Fork modification: $200
Shock modification: $75
GALFER BRAKES USA
5788 Dawson Ave.
Golita, CA 93117
800/685-6633
Front pads: $36
MICHELIN TIRE CORP.
P.O. Box 19001
Greenville, SC 29607
803/458-6053
Front Hi Sport TX15: $179 (120/70-17)
Rear Hi Sport TX25: $197 (150/60-17)
Front slick: $179
Rear slick: $225
Front rain tire: $179
Rear rain tire: $225
SCOTTS PERFORMANCE
PRODUCTS
2625 Honolulu Ave.
Montrose, CA 91020
818/248-2553
Steering stabilizer: $400
TRU-TECH
2180 San Antonio Place
Corona, CA 91720
909/280-9010
Quick Caps: $180
WHITE BROTHERS
24845 Corbit Place
Yorba Linda, CA 92887
714/692-3404
FMF pipe: $180
Pro Circuit silencer: $73
IMS wide-ratio gear set: $500
White Powerfilter: $34
Regina 520 RX3 chain: $65
Eibach fork springs: $80
Eibach shock spring: $90
WB motard front brake kit: $465
Braking oversize rear brake: $272
Fastline front brake line: $48
AFAM Superbike handlebar: $53
Galindo Superbike grips: $8
Ceet seat cover: $40
WB motard front wheel: $725*
WB motard rear wheel: $788*
* Wheels come complete with Talon
billet alloy hubs
