RACER TEST
would probably have ensued - but I was
abo sure I ha d n't imagined it.
"No, you d idn 't," sa id Aaron Slight's
chief mech a nic; Adrian Gorst, w hen I
returned to base for a change of und erwea r. "Aa ro n was co m p laini ng abo u t
th e same thing for mu ch of th e weekend, till we got the right front tire fitted ."
The Castrol Honda RC45s
Rubber problem, then?
"No, you have the sa me tire John has
u sed all se aso n long, at eve ry trac k,"
sa id Mic helin ma n Jea n Herisse . " He
likes the softes t compound but the hard est construction."
""John 's always looking for fro nt-tire
g rip," agreed Nick Goodison. "And he
uses very so ft fork se ttings, wh ich he's
Honda RC45 tech:
Reinvented racer
R
id ing the Ca..tm l Hondas of Kocinsk i a nd Slight a t Sentul rev ealed on e crucia l fact: To win
the World title this yea r, Honda reinv ented the RC~5 . motorwise - a fact confirmed by talkiug afterw ard to the leader of the development team ch arg ed wi th bringing up bab y. H RC
Chid Engineer Syu hei Na ka moto.
"Betwee n the 1996 a nd 1997 seasons , we- made man y detail cha nges to the en gine specifica tion; " Nakamo to 5. Y "On its own, each wa s maybe quite sma ll - but together, they gave time by Ducati on their big-bore V-twin
but never before on an eng ine with four sma ller cyli nders) are used seq uentially.
"Before, with a single-injecto r sys tem, we needed much gaso line at ma ximum revs, bu t not so
mu ch on the bo ttom side. which compromised performance," akarnct o says. "For this yea r, twin
injectors not only mad e developm en t easier , but also im proved engine settings a U thro ug h the
powcr CUI V e: We use the first injecto r only till 8fKX) rpm ; then th e second one comes in a s well. to
give maximum fuel flow. We can change the point a t which this hap pe ns, but so fur we did n' t do
so at r.lCCS, on ly in he stin g . But it mad e a big
e
improvement to engi ne performa nce,"
Thi s step larg ely enabled H RC technicia ns
to fill in the mi d range tr ou gh in th e power
cu rve, w hich o n th e RC4 5 had p re vi ou sl y
necessitat ed the use of va ria ble-length inta ke
trumpet:" in the four 4hm m th rottle bodies, to
provide a so lution. Just as w ell. becau se fitting
the second injector meant there wa s no longer
an y !>pacc ava ilable for the "ad justable air funnels," as they're called in HR C · s pe ak , wh ich
are in any case banned in AMA Supcrbike racing, where Hond a a lso aims to succeed . Bu t
par t o f th is i mp ro ve me n t a ls o ca me fro m
Hond a' s abil ity to fine- tune the EFI mapping
for va rious parts of the power cu rve via the ir
o n-bike adj us ters. Duca ti can only do this by
swapping EPROM chips on its less user-friend ly Marelli injection package, whi ch d oes howev er hav e the ign ition incorporated in it, for a
fu lly integ ra ted e ng ine- ma nagemen t system .
Hond a u ses a Nippodenso ig ni ti o n wh ich ,
w h il e fu ll y pro g rnm rna ble eve n dow n to
choosi ng a differen t cu rve for each gea r in the
six-speed gearb ox, is still com pletely se parate
from the EF1.
"T he truth is that w e ha ve two se pa ra te
su p pliers," Na ka mo to reveals , "one eac h for
injection and ignition - and maybe we wo u ld
need d third to provide US with a n in tegra l systern ."
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20
Still, one area in w hich the two pa ckages do mee t is on the power sh ifter for the gearbo x,
which this ye<1T for the first time also works by cutting ou t the ignition (like on ot he r bikes) as
well as the EA, nn which it only inte rve ned before. But the transmisi.ion still d oesn't us e d dry
.
clutch, even at the em.t of the extra power sacrificed by the increas.ed d ra~ of the w et oil-bath unit
used on every .....orks V-fou r Hon da Superbike in the pelst decad e.
"'Thc problem is that our back~ torqu e limiter would necessit..1te a very Luge oil SC'al with a d ry
d u tch," Nakamoto sa id. "Not only does this create C
{lnretl\ dbou t oil leaks , but aL<;() cons u mp tion
- a nd plea~ u ndt·Nt., nd thi s In.lc hine was a l"Odeveloped for su cco." in the SuZUKa 8 Houn., a. .
.
weU as other long -dista nce events."
Ho.....e\·er, Ont.' of the ma ny detail improvements for 1997 was the ad opti on of a Ducati -styl e
~i d e oil ft.'t.od fur the cra nks haf t, to red uCt.> drd g - though the dl.~ign of the tit..m iurn rod s, no.-o-ring:
sh p~r pist ons ~ ving 13.2:1 com pression, cylinde r-head porting dIld cam profiles all remain~
the :;.arne. W hi l~ they are the Mm~ sizes as before, thp dt"Sig" of the titanium va h:es was cha nged
sli);htly, thou ~h , a nd springs and retai ners were new,
Yet tha t hdty power inCft>a~ hasn 't been acrompanied by a notable step up in top speed, " ;th
term ina l velocities. hard ly mu ch high er th b year tha n las t.
11lat's right. " Sa id Nakamoto. "'\ ¥hile our power inCTf'aSf" for thi.. St"ason \V s a big improve-a
me-nt, !!iotra ight -line speed was not so different, MauSt" we calrula te we na "CI 5 bhp more po\\·er
for each half-mile- pt'r-hour more in top ~pt"l"d . Tht.' problem b .lcrodyrumics - and of course, for
Superbike, we cannot eh.mge the body sha~ from the homologated street bike, not like in GP, So
the main bcn~fit of thi s extra powe r is in the improved acceleration you expt>rienced ."
This helps expla in how .1t speed circui ts like Hockenh eim or Daytona , w here acceleration isn' t
very sensiti ve to cha nges o n . W e u se a
r e lat iv e l y st iff r e a r sus pens io n w i th
9.5kg spring and reduced co mpression
damping, aU of which we nev er change.
But Michelin brin gs any w here from 10
to 15 new rear tires to each race, and for
a rider as sensitive as John, this can be a
big problem timewise, because now th at
pre-ra ce test ing h a s been b a nn ed, in
four ho urs of track time a t each round
between practice and qualifying , yo u're
st ru ggl in g to tr y the m a ll, as w ell as
work o u t the ideal comb ina tion in terms
of rid e height, wh eelbase, gearing, shock
ratio a nd front suspensio n . The eccen tric
ad juste rs on th e RC45 are a p rob lem ,
because if you m a ke o ne change, e ven
on the gearing, it alters everything back
so mu ch a factor as ou trigh t top speed, the Honda's supremacy wasn't so evid e nt - whereas on
tighter tracks like Laguna Seca or Albecete. prev iousl y thou ght to fa vor the more nimble Duca tis.
the RC45 w,15 un bea table, tha nks to its awesome accelera tion.
Honda ' s main developmen t for their cham pion..hip season wen t into the mot or, and it pa id off
with the Wor ld title. By contra st, the chassis w as ch ang ed ve-ry little, say s Na kamoto, with the
only majo r novelty be in g the introd uctio n of it racing versio n of Honda' s CBS linked-brake sys~
tern , wh ich wa s introd uced on the CBR1100XX Blackbird str e bike a year ago . Whether this was
et
ad opted on the RC45 for mark etin g or fu nctiona l reasons is hard to d ...'Cipher , Of the Cas trol
Hon da team's two rid ers , Kocin ski d oesn ' t use it on the gro unds that it does noth ing he could n' t
do himself w ith :;cparate foot and hand controls, whil e Slight ""')IS he likes it because it makes the
bike more stable under the heavy braking that's part of his style.
TI,e racing CBS linked system on the RC45 work. Viol .111 electric servo motor mounted und er
the chassis cr ossmembcr beneath the sea t. It is co m p u te r-con trolled via a sen sor, w hich mon itors
pres sure on the front -brak e lever . This leads the servo to operate two of the four pis ton.. in the
rea r-brak e caliper an ins tan t before the front . to encou rage a pro-dive mod e, resulting in a lo w cr
cen ter of grav ity as WE'll itS more balanced - and thus, theoretically more effective - braking. But
Honda eng inee rs can a lter the settin gs via the com pu ter mo unted a bove the se rvo, working on
three pa rameters: the pressu re on the rear brake, the len gth of operation , and the time lag between
fron t a nd rear, adjustable over a .t- to-m-of-a-second ranhc. And. of course, the rider can still
increase rear-whee! braking force at will , by using the foot lever to operate the seco nd pair of piston s in the rear cal ipe r, via the secondary, con ven tio na l hydraulic system .
Honda sa t ou t the Supcrhike class a t wor ld level for three ye-ars a t the start of the decade wh ile
it wo rked on the next-gen eration successo r to the World -title-winn ing RC30- all the time cont inuing to win end urance races like the crucial Su zu ka 8 Hours (ru n to IT Form u la One rules, thus
permitti ng fu ll-on four-stro ke racers with jus t the engine based on a s treet bike) with the RVE Out
esc
for the Jap.l ne compa ny most closely connec ted with top-level four-stroke racing, thi s absence
from conte ntion as the Su per bike class a ttained sign ifica nt world status mu st hav e been acu tely
frustrating, in comm ercial as well as sportin g terms - es pecially as the RC45 was at least a yea r late
when it final ly appea red at the en d of 1993. The new bike had a troubled debut season in 1994 thou gh A aron Slight's record of eight second -places showed it could be a conte nder - and suffe red
handling problem s exacerbated in '95 by a swa p from Dunl op to Michelin tires.
How ever, in typica l Honda fashio n, ded icated work by its .JTm y of cleve r eng ineers has eventua lly had its ju....t reward - backed u p, no doubt, by a bud get wi th lots of zeroes on the end: The
co ntend er for the w orld cr own has no w beco me cha m p ion a t last. "T yp ica l" Honda? Lixten .
wh en wa s th e las t tim e that
th ose cle ver peo ple a t HRC
fa il e d - sooner o r la ter - to
a c h ie ve s u p re macy i n a ny
class of ra cing they set out to
conque r?
Sooner or la te r, Big H is
gonna get ya...
Close-up photos reveal two
of the most significant
changes to the modem
RC45: The twin-InJector
PGM-Fl fuel-injection
system (left) yields
tremendous horsepower
hikes over the previous
version. The servo
arrangement tor the CBS
linked-braking system
.(below) hides under the
seat.
