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Team Yamaha feels water-cooling is unnecessary for Open bikes. New
exhaust pipe routing aids cooling. ( B~ l ow) KTM has suspension bugs.
:M otoCToSS Technology..;.
Where now?
By Peter Clifford
Even though he made history by being the
first man in si x years to win a 500cc motocross G rand Prix on a non-Japanese machine
w h en he clinched an o verall first in the
French World Championship
ro u nd, Danny Chandler isnot
th at impressed with th e wa y
th e Eu ropea ns work a t machine
20
d evel o p m ent com pa re d wit h the
Americans back home. " I reckon that
in th e U .S. peo pl e a re mo re open m inded a bo u t sortin g a bike o u t, th ey
will try a ny thi ng. H ere th ey a re m are
set abou t what they wi ll and will not
do. There is not too much wron g
with the KT M, tho u gh. We just ha ve
to get it worki ng a bit better a ll
'ro u nd ."
Chandler may not have fo und the
Europeans as inve ntive as he wo u ld
wish bu t th ere arc sti11 pl ent y o f ideas
a bou t wh en it co mes to the fu tu re
deve lopment of G P machinery, and
w hen ex-500cc Wo rld Cha mp io n
H ak an Oa rlqv ist mak es a sta teme nt
a bo u t it yo u shou ld listen . " Wha t we
want is less suspension travel. " says
th e hard man o f raci ng bu t tha t is not
beca use this tough gian t of a motocross ace wa nts to go back to th e da ys
Current 500cc points leader. Dave Thorpe, feels the works Hondas don't
nee~ impr~vement (Below) Kawasaki will use Dunlop tires all year.
,
whe n a works tw in -sh ock BSA o r
H usq varn a had three in ch es o f travel
or tha t he wants to p rov e himself the
bett er man wrestl in g suc h a ma chine
arou nd th e count ryside. What he does
mean is that th e 11.8 in ch es (300m m)
o f suspension a t th e front a nd back o f
h is wo rks 500 Ya maha is a p roblem
in itself .
" It wou ld be perfect if we co u ld get
down to a bo u t 9.8 in ches (250m m) o f
sus pe nsion that performed as well as
th e 11 .8 in ch es we ha ve now. We
werit to longer su spension tra vel so
th at it would soa k up th e bumps but
it mak es th e bikes high and slo w to
steer." In pursuit of th is end Ca rlq vis t
is working wi th Ohlins a nd Yamaha
on a new-gen eration fron t sus pe nsion sys tem . T hey ha ve been testing a
linked fro nt fork system quite different to th e telesco p ics but no t th e sa me
as th e Ribi system Roger DeCo ster
tri ed on th e works H ondas a few years
ago. Deta ils are secre t as yet an d a t the
moment th e replacem ent is so me 3.3
pounds heavi er th an the lat est telescopic Ohlins forks bur th at weight
wi ll co me down a nd th e n ew design
docs not va ry the len g th o f th e wh eelba se o r m ak e the bik e wa nt to sta nd
u p in th e co rners, which has been a
criticism o f o ther linked svsterns. " It
is comi ng a lo ng well ," s~id Car lqvis t, " bu t a t th e moment we are ca nrin ui ng to race with the Ohl in s upside-down fork wh ich works well. "
Th is system has th e in ner chromed
for k lubes on th e bo ttom, holding th e
fro nt wh eel sp ind le. This reduces th e
un sprung weig ht making th e task o f
suspens io n co ntrol eas ier and also
ge ts rid o f th e underneath - th e ax le
fork extensions wh ich so me times
ca tch in ruts while co rnering.
Front suspension is o n ly half the
ba tt le. th o ugh. a nd the rear w heel has
to transmit th e eng ine power to the
gro und. " \ \' e cou ld h ave mo re power
from th e engine if we co u ld p u t it on
th e gro und but at th e mome nt j ust
over 60 bhp is as m uc h as th e suspen sio n a n d tires ca n use. Th e 250s are
o n ly p roducin g 40 to 45 bh p an d th e
lap lim es a re not much slo wer, " contin ued Ca rlqv is t. Far th at reaso n the
500 Yamaha is air-coo led . to keep
th in gs more si mple. The added power
potent ial o f wa ter-roo Iing isn 't nee ed
d
- that was tr ied in th e p ast bu t now
th e cooling tri ck o n the works bike is
a specially-sh aped exha ust p ipe which
deflects ex tra air at the cooling fins.
The Yamaha does have a variabl egeometry exhau st port tha n ks to the
re n rrifuga llv-con tro llcd, cylindr ical
p ow er valve th at aids power band
Ilexi bili tv.
G ett in g th e pow er to th e ground
need s mo re development a nd th e flyin g Swede has so me firm ideas on
how it would be acco m p lish ed. " We
hav e done so me wo rk with th e positions of th e sprockets and swi n garrn
as well as th e nylon cha in ro llers bu t
th ere is more work to be done so th at
th e acce lera tio n does n ot co m press
th e suspension and ma ke the bike
lose tract ion. I a lso thi nk th a t tires
will ge t wider to gi ve more grip a nd
in th e end both ,th e front and rea r
suspe ns io n will be co ntro lled by a
m icro -co mputer th a t will cha nge th e
suspension a ll the lim e."
Someon e else wh o has g iven a lo t
o f thoug h t to th e wa y thi ngs are
devel oping is teen ager Kurt Nico ll ,
Chand ler's teamm at e, wh ose KTM
ha s h elped him to a grea t sta rt to the
'85 sea son, putting h im fifth in the
