Ifonda mechanic Eric Crippa swungllopen the rear doors of thi ied, whitiand blue team transportet allowing a shaftof midday sun to illuminate the interior.Therg shoehorned between the workbench-es, welding bottles and racks of spares wasthe motorrycle of a thousand riders' dreams.A slender silhouette, it looked surprisinglysmall next to its 1986 stable mate. MartySmith stared intently, then began shufflingaround near the back of the truck, tryingto get a better view-a glimpse of the forks,the tiny aluminum tank, the shocks, theswingarm, the engine that carried him to onestunning victory after another, to a level ofmotocross stardom enjoyed by few riders inthe history of the sport. After a few mo-ments, Marty began looking at the Hondamore hesitantly, the way someone gazesuncertainly at an old friend during a highschool reunion. Was this really the samemachine? His only verbal response was anelongated "Wow!" not unlike that of theaWestruck spectators who first stole aglimpse of the bike at its 1975 HangtownNational debut. Micky Dymond carefullyscanned the RC as Eric rolled it out of thetruck and lifted it slowly onto its stand.

"I used to have one of these," quippedMicky, "for my G.I. Joe."

24 DIRT BIKE / OCTOBER 1986

TEN

A look atthelegendary 1975 RC|25

& how it stacks upagainstthe 1986works/production

hybrid

COMIC RELIEFIn 1975 the RCl25 Honda works machine

was a technological wonder that representedthe pinnacle of the mighty Japanese moto-cross effort-the product of HRC's mostgifted mechanical artisans. The bike and itsrider carted off almost every National win,as well as the 125 title. Along with its 250and Open class brothers, it established amystical aura that surrounds Honda's worksmachines, even today. When Honda goesracing, they do it to win, and their com-mitment is as evident and uncompromisingnow as it was in 1975. Their strategy is sim-ple: Hire the best riders and build them thebest equipment. One thing, however, haschanged, and that's the degree of secrecysurrounding the high-tech works wonders.Of course, there still aren't bus tours of thecompany's R & D facilities. In this age ofproduction-based racing, however, the RedGiant seems a bit more tolerant of jour-nalistic types who like to pry and snoop with

Marty Smith jumped oll his Kawasaki KX250to take a few laps aboard the RC125 worksHonda. Mafty rode the machine to the 1975125 National Championship; Micky Dymond(43) is on his way to claiming the'86 crcwnwith the latest CR125 works Honda.>

By Fran Kuhn

q.q

\

into American Honda's racing stable. All ofthe bikes had hand-built, chromoly framesand thick-walled oval-section aluminumswingarms. The lightweight items found onnearly all of today's production motocross-ers were, at the time, reserved for the worksarsenal only. Saving weight (not money) wasHonda's prime consideration, and the totalballast of the RC, as delivered from Japan,was just 168 pounds-eight pounds underthe AMA,zFIM minimum for 125 classequipment. This minor dilemma was con-veniently solved by casting a new cylinderhead in solid copper, boosting the totalpackage to just a hairsbreadth above thethen-required 176-pound minimum.

Even now, Honda's penchant for savingweight is startlingly evident in all the RC'smajor components. Both triple clamps arefabricated in the flyweight mold: The lowerunit is carved from billet aluminum; the up-per one is sand-cast magnesium, and theriders were able to choose between three dif-ferent fork bridges, each offering varyingamounts of steering leverage. Depending ontrack conditions and rider preference, eithera high or low seat,/bar combination couldbe fitted. The "high" combination is nowpermanently in place. The bars are chrome-plated Bates models, and the overstuffedseat's base is the only stock component onthe entire machine, except for the shift leverand a few nuts and bolts.

loaded cameras and tape recorders, even go-ing so far as to offer test rides aboard thecoveted works equipment. Back in the olddays, the veil of secrecy was drawn and arc-welded shut. Precious little information wasavailable about the goings-on inside the fac-tory, and even less was known about thebikes. Now, ten years after the RCl25 was

rolled into mothballs, a closer look is inorder. Just how much have things changed,not only with the machines, but with theriders and the sport itself?

THE FACTORY CONNECTIONHonda of Japan built no more than five

RCl25s for the 1975 racing season, and threeof the machines eventually found their way

The RC's wheels, hubs and brake back-ing plates are sand-cast magnesium; thehubs are laced to gold-anodized DID rimswith heavy-duty spokes, and a set of vintage1975 Bridgestone knobbies wrap around thelightweight wheel assemblies. The frontfender is plastic, and the rear is hand-laidfiberglass, as are the red-and-white side-

OCTOBER 1986 / DIRT BIKE 27

A blaclr ph$fic guard is bolbdta thefiC1253 front dowmubera pqvent mudbuildup cn the oopper cyltnder head. Thebfke ssesa standard GF?$O Flsinorecfuicl.r, and a large idler Eeat housedabove ihe kicksfarter nras lntended to drivea Brop.osed luel iniect,'or system.

Donny Emlerol FMFbuiltfie RGb op.and-over pipe to glve fhe englne a brcaderpowerspred. The shndard CFt25 Elsl-nore chamber actualty delivered molrchorsepower, but the spread was unaeaept-ablyandignitiron sysleras, each ang with a dilletenttlywheel weight to controt wheelspia.

<How maeh lrve things clranget? Backtn '75, the RG125b alumlnum swinga|m,airloillspilng Showa shocls, and single-Ieading btakes we.rc t te besl thdt ffofleyeould buy, ln aomparlson, fhs 1986 pro-ductlsn machine u*es a nrodified aluml-num swingarm and a pawefivl disa bnke,H/hieh is not anly bette[ lut co',siderahlycheaper.

The IW, FC125's forks feature safld-castmagnesiu m legs and hand -cafi 6d dampetrods, Iota, traveL' Juct over seven inches.Even il lhey werc made ttofi cast iron, weUstill preter rhe €6 forks ta lha ald tu0es">

An aluninum pfaie couers a casting aI thereat ol the eylinder lor a fiuet-injection noz-zle, fhe otiginal RQ catbuteto4 a 29mmKeihin, is saad-cast alumlnum. fhe |.r.talcost of fhe RQ'125 in 1975 dolrars is eofima'ted at$18,000.

panel numberplates. The rear of each ovalplate is flared to clear the wide upper bodyof the factory Showa shocks, and each panelhas been given the Swiss cheese treatmentwith an exacto knife to improve the flow ofcooling air around the damping units. Theshocks feature a then-revolutionary air,/oillspring system and a set of unusual-looking "fork" gaiters on the lower half ofthe bodies. While the factory Showas lookedstate of the art in 1975, they were actuallydeficient in several critical performancecategories.

"They were extremely heavy," recalledJon Rosenstiel, Marty Smith's mechanic forthat championship season. "We couldn't getthem working right and eventually switchedto a set of Gas Girlings, which Marty usedfor the majority of the season."

Jon, perhaps more than any other person,intimately understands the strengths andweaknesses of the RCl25's formula. As thekingpin of Honda's elite factory mechanicsin those glory years, Rosenstiel (now a fac-tory wrench for Yamaha's Broc Glover)established a reputation for being both ameticulous craftsman and a highly imagina-tive technician. He took the base productcarved in Japan and made the numerousmechanical adaptations necessary for suc-

28 DIRT BIKE / OCTOBER 1986

cess in a highly competitive Statesidemotocross environment. Nowhere was hishandiwork more apparent than in the devel-opment of the RC125's engine.

IMPROVING THE FORMULAEven a machine delivered direct from the

womb of Honda of Japan's Racing Depart-ment is not perfect, and the 1975 RC125 wasno exception. Much of the motorcycle'sdevelopment work was done in the labora-tory and on the dyno, far from the cutthroatrigors of real-world motocross competition.To further complicate the problem, ridersin the U.S. motocross arena-particularlyMariy Smith-were developing their talentsat a rate considerably quicker than pilotselsewhere in the world. One pounding lapin the hands of a boy wonder like Smithcould isolate more weaknesses in the ma-chinery than a legion of white-coated tech-nicians and a hundred hours of lab testing.As Marty's riding ability improved, Jon wasfaced with finding new ways to coax morefirepower from the tiny l23cc mill. This wasno easy task, as the engine was already quiterevolutionary in its original configuration.The cylinder serves as a good example: Thebarrel offers the option of utilizing a con-ventionally aspirated induction system (car-buretor) or mechanical fuel injection. The

rear of the cylinder casting carries a port forthe proposed injection nozzle, the optionalsystem to be powered by an idler gear run-ning within the kickstart lever's housing.Because AMA rules restrict motocross ma-chines to the realm of conventional aspira-tion, the system remained unused in the U.S.,though it likely reached the prototype stagein Japan. ln 1975, mechanics had the op-tion of running either an iron-lined orchrome-bore cylinder. While the plated cyl-inder offered both lighter weight and bet-ter performance, problems with chromeflaking and seizures forced the team toswitch to the iron counterparts early in theseason. Both the piston and rings are slightlymodified off-the-shelf production parts,and the clutch is a straight-cut 250 Elsinoreitem. The close-ratio transmission is a fac-tory one-off cluster that sports hand-cutgears.

The carburetor originally supplied byJapan and fitted to the bike today is a29mmKeihin-a sand-cast machine-shop specialthat mechanic Crippa says would likely havecost thousands to make, even in 1975 dollars.(Eric spent hours scraping layers of hard-ened white crust from the precious blenderbefore the machine could be started for ourtest.) Back in '75, when the need for more

Micky Dymond's ride aboard the RC was arcvelation, "l can't even imagine ttying toride a Supercross on lhat bike," said Micky."About the only thing that's rcally goodabout it is the weight;'

power became obvious, mechanic Rosenstielswitched to a 34mm Mikuni, a far more ef-fective choice for the smooth, fast Americancircuits of the day.

The search for more power also producedrevised port configurations and an up-and-over expansion chamber developed byFMF's Donny Emler at Rosenstiel's request.

"The new pipe actually didn't hit as hardon top as the stocker, " said Jon, "but it didgive the bike a broader spread. Marty andTommy Croft (Smith's 1975 teammate) likedthat a lot better. "

The final combination of Rosenstiel'smechanical expertise and Marty Smith'sriding ability easily snared Honda its sec-ond number one plate in two years, and thechampionship 1975 RC was quickly retiredto HRC's California warehouse. To the bestof anyone's knowledge, it's never been runsince-until now.

THE RIDER'S VIEWPOINTAfter more than half a season aboard his

Chris Haines-tuned CRl25 works/produc-tion machine, it's not hard to imagine MickyDymond's reaction to his first ride aboardSmith's 1975 RC racer.

"It feels like it's pretty fast," said Dy-mond, "but you're pretty much limited asto how fast you can go by the suspension.I can't even imagine trying to hit a doublejump with it."

After several laps around Marty's hillsidepractice track, Micky had tasted enough1975 technology and was ready to jumpback aboard his '86 machine. Was thereanything good about the old bike?

"Well," reflected Dymond, "it is light,and it's really low to the ground. In someplaces it's almost too low. . .a few times I30 DIRT BIKE / OCTOBER 1986

almost fell over just from leaning into a turn.I tried to put my foot down for a corner, andit would drag on the ground. I can't imaginetrying to go through a set of stadiumwhoops!" Marty quickly commented onDymond's observations.

"They really didn't have stuff like thatback then," said Smith. 'At the most, theyhad maybe one double at a time-two dou-bles, that was unheard of. . . they would havelaughed at you if you had even mentionedsomething like that. " Marty's evaluation ofthe RC's motor was surprisingly good, evenif it has been ten years since he last rodethe machine.

"It has a lot of potential; it feels prettyfast, but the suspension holds it back," hesaid. "The bike doesn't go anywhere whenyou gas it. It just sits there and bouncesaround on all two inches of travel."

Marty's brief spin on the '86 works ma-chine wasn't really a revelation. He's beenactive in riding and local racing since retir-ing from Team Suzuki back in 1982, andsince then, has won several not-so-minorevents, including three "King of the Desert"titles and the "Champs of the Past" crownat the recent Magoo Invitational. He's a fastrider who knows what a motocross machineis supposed to do. Still, he thought Honda'slatest-generation works weapon was superb.

"It's awesome," said Marty. "The backend works great, and it has good horse-power. The brakes are really strong, espe-cially the front. . .the whole thing worksperfectly. "

And how did it compare to the 1975 ma-chine? Marty's reply came without as muchas a moment's reflection.

"You could probably compare those twobikes the way you'd compare a '56 Volks-wagen Bug and a brand-new Porsche 940.The difference is unbelievable."

SOME THINGS NEVER CHANGEGiven the intensity of competition among

the Japanese factories, the level of techno-

Even with an additional 30 pounds olweight, the'86 works machine holds everypossible advantage ovet the'75 bike, Martywasn't willing to try anything radical on theold RC; Micky wouldn't even think ol it.

logical advances made over the last decadeisn't surprising. Of course, the very natureof the sport has been radically altered bythe passage of time. It has changed from a

more-or-less casual and lriendly affair tosomething closely resembling a hardlinebusiness venture. This transitiorr has had itseffect on the rider/mechanic relationship as

much as any other aspect of professionalcompetition.

"Nowadays, the riders come in from prac-tice saying, 'This doesn't work,' and 'thatdoesn't work,' and 'change this,' " saidSmith. "Back then, we'd come in and maybesay, 'The chain's a little loose,' or 'Put a lit'tle air in the shocks.' Now, the bikes are so

technical. Back then, we were only concern-ed with having a little more horsepower thanthe other guy. " Micky Dymond listenedcarefully as Marty continued, dividing hisattention between the ex-champ's commentsand some race photos of Smith tiom the '75season.

"Nowadays, the equipmenr is so impor-tant," offered Marty, "irt 1,975 everythingwas new. The sport was so rle!! that we werejust taking each track and each bike andeach year in stride. I had a lot of other thingsto concentrate on besides the bike. " Smithpaused for a moment as Micky, shaking hishead in utter disbelief, held up one of thephotos showing Smith airbtirle on the oldRC, perhaps 20 feet above the surface of thetrack.

"What about this!" gasped Dymond. "Ican hardly believe you did lft,s on thotblkelWhat were you thinking?" Marty reflectedonly briefly before delivering his reply.

"I guess I ju'st didn't think, " said Smith."If I had, I never would have done it." !