Cycle News - Archive Issues - 1980's

~ ~ .. L_ . l!"') 00 O"l ...... ~ C'J C'J ~ ~ ~ Former 500cc World Champion Hakan Carlqvist wants less front and rear' wheel travel on the works Yamahas, from 11 .8 inches to 9 .8. cha m pions h i p aft er two rounds. Like Car lqvist, he was sure that more p eak power wa s not need ed. "All o ur engines are a little different but say thi s o ne gives 63 bhp , it would be no problem for the factory to get 78. The weigh t is th e same, we a re on m in imum limit a t 224.9 pounds ( 102 kg ) but it cou ld easi ly be 98. We could do with a bit more power flexibi lity and I th i n k in a few yea rs a ll the bikes will h ave some sort of exha u st po we r va lves. At th e moment m ost o f th em don 't work ver y well , th e response is not quick enough but that will get sorted out. One is co m i ng fo r the KTM - th e 125 ha s it already a nd in a few weeks so will th e 250." One 250 that seems to be working verv well now that it has a n exha us t power va lve is th e latest Suzuki as ridden by Michele Rina ldi , lying second in the 250cc cha m p io nsh ip behind Yamaha rider J acki e Virnond. Rinaldi's machine is fitted with an exhaust chamber sim ilar to th at used on the Suzuki RG500 GP road racing engine. Its effect is similar to Hon da's ATAC in that it in creases th e exhaust volume a t lo w revs but on th e Suzuki the cha m ber cas ting is added to th e cylinder head rather th an to th e exha ust pipe, The cham ber is va lved by a rotating cylinder that is operated centrifugall y o ff th e crankshaft. While si m ila rly a more-fl exibl e powerband would be an advantage for the 500 KT M , the suspension still needed to be improved to cope with the o utput according to Nicoll. "We defi ni te ly need som e sort of antisquat system to stop the engine power compressing the rear suspensi on . That wou ld be a big advan tage if a nyone could get it sorted out. So would a replacement for th e telescopic front fork but thi ngs like the Ribi system have not worked in the past because th ey made the bike diffi cult to corner : We work with White Power wh o a re ver y good a nd th ey have th eir versio n of th e upside-down front fork but th e set up doesn 't su i t me at th e mom ent a n d I still have the Marzocchis o n th e front with th e White Power unit on th e ba ck ." " Th e KTM rear su spe nsio n , like most others in mot ocr oss, ha s a singl e shoc k with a rocker ar m a nd link- age to provide a rising rate. As Ni coll pointed out. one of the ma inproblems was getting enough time to do development work . " I like testing wh en we have time awa y from racing but there is too much to try a t the meetings. We try to get the su spe nsion set-u p beforehand, ch an gin g th e o il level.ida rn per rods and springs in the forks. We lea ve th e work on the rear units to White Power, and we try to cha nge as little as p ossible a t the m eeting because th er e arc still tir es to sort out. " L ike m ost other riders Ni coll ha s no tir e co ntract. Mo st ride rs arc barred by th eir factory contracts from ha ving an y agreement with one si ng le tire manufacturer. so th ey ca n choose th e best tire o n th e dav . It means so rting o u t the best, front and back from Dunlop, Pirel li . Mi ch elin, Metzeler o r Barum. That doesn't mak e it easy · for th e rider or the tire co m pa n ies try ing to sort out n ew tires as Ni co ll suggested . "There is n o time to test all th e d ifferent tires and yo u ca n ' t aff ord to waste time tr ying out tires that are not fully developed. " With th ese probl em s in mind, Kaw asaki and Dun lop have rea ch ed an agreement to work together with th e Kawasaki men, Britain's J em Whatley and Dave Watson, Ireland 's Lawren ce Spence, Belg ia n Georges J abe and Ita lians Michele Magarotto and Guiseppe Grola. As Alec Wright, bo ss of the British Kawasaki team pointed o ut, it was the onl y sensible so lution in the face o f incr easin g development pressure on riders and me chanics. " It is getting li ke Grand Prix road ' racing as the bikes have wat er -cooling a nd power valves it takes tw o h ours to cha nge a set o f rings ins tea d o f 30 minutes. It is getting to th e point wh ere we need three o r four me ch an "ics per rider a n d we arc a p p ro ac h in g th e FI;\I to a ll o w lon ger practi ce sessio ns . Don't forget we ca n' t test th e week before lik e th e roa d race teams ca n , G oing with Dunl op ha s helped us with time. Th ey are good tires a nd th ey give us four possibilities for this Fr en ch GP. If we had 10 trv a ll th e different makes of tires a vailab le th er e would be 22 d ifferent typ es to tr y." Rath er th an su gges ting th at o ne Ro lf Tibblin (J o rgen Nilssen's mechanic) says last year's dual-shock rear suspension was good, but single-shockers are what the pub lic .w ant s. point suc h as anti -squat n eeded look in g at, Wright sees a general line o f development to im pro ve sus pe ns io n a nd engi ne power so th at the machine ca n be tuned to th e ever-c ha ng ing nature o f a circ u it. "Th in gs like p'o wer sag in th e rear sus pe ns io n we ca n co pe wi th OK. but you have to tunc the machine to th e cir cui t, which cha nge tremendously in two hours. We have different pipes, cylind ers, Ilvwheels a nd ca r bs 10 alt er the power o u tp u t and then tlu-r« arc th e su spension and tires to change." It might seem tha t th e rider wh o co u ld sort out a ll th e technical iti es would hav e more of an advantage th an th e man wh o co u ld sim p ly ride fa st , but in Wright 's team th e responsibility for techni ca l changes is largely lif ted from th e riders ' sho u lders. "The technician s and I wat ch th e way th e bikes perform in various section s o f th e track and th en we mak e cha nge s to th e bike. We also have a video sys tem 10 film th e bik es so th at we ca n stud y th e wa y th ey work. Honda h a s th e same and as we a rc in a d ire ct battle with th em we wa tch w ha t th ey d o as well. " Honda 's Dave T horpe seem ed prett y unconcerned by a ll th e o p pos itio n's inter est in techn ical de velo p me n t. " Ou r bikes are just so good we d on 't reall y n eed 10 do a n yth ing to th em . 1 don 't think th at th ere is a nv ben ef its in wh at th e o ther tea ms a rc doing because if th ere was, we would a lrea dy hav e i t o n o ur bikes. H onda see ms to do everyt h i n g fir st ," sta ted T horpe pl a inl y, Even wh en as ked wh at h e would do if give n a ma gi c wan d to wave ove r the wo rk s H onda, h e sa w no need for im p ro vemen t. " \ Ve don 't rea ll y n eed a ny cha nges. Th e th in g is that rid in g fo r a co m pa ny lik e Honda yo u do have a ma gi c wand because th ey ca n g ive us an yth ing we want. " Lik e th e o ther factory riders, Thorpe wa s su re he had all ' the power he needed a nd pointed ou t that th ey didn 't even need th e ATAC box es used to mak e rnanv o the r Hondas m ore flexib le. " We'lried th em for a few GPs but th e butterflv valves ca n n ot o pe n and close quickly en o ug h to keep up with th e thrott le response o f th e engi ne . Wh at will come, I think is a more-advan ced ignition system beca use I have seen th e mi croch ipco ntro lle d ignition o n th e works 250 H onda a n d I think th at may appear o n th e 500." Not everyone agrees th at the usua l line of mot ocross development is correct a n d n ecessary. Swede Rolf T iblin, 500cc cha m p io n in '6 2 and '63, n ow loo ks a fter fell ow counrrvma n J orgen Ni lssens works 250 Husq varna . H e isn' t co nvince d th at "th e Swedish firm 's final ca p i tu la tion a nd adoption of th e roc ker -arm sing leshock sys tem as a repl acem ent o f th e o ld twin -sh ocks was 10 anv adva nra ge. " I don 't th ink th at there is a ny thing wron g with th e tw in- sh ock system but we r o u ld nt sell a nv Huski es so we had to bui ld the mono'sh ocker, " he sa id af ter N ilssen had won th e seco nd leg of th e So u th Af rica n GP o n hi s new wat er-coo led mach in e. " Yo ~ ~ ha ve to bu ild wh at peopl e will bu v. So i t seems th at even th e fac torv specia ls a rc a ffected by m ark et force~ a s m uch as p ure ra ci ng deve lop men t.e 21

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