Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/125853
inertia of 200 lbs , and the motorcycl e starts accelerating very ra pidl y. . " Fa st motors ar e good. n is an obvious truism in japanese ra cin g engine design so a fast motor goe s into th e production bike, on e wi th out much flywheel effect . The revs climb with a sligh t throttl e tw ist , th e pow er gets transmitted to th e rear 4 .00 X 18 j ap an ese Du nl op an d the ina deq uate ti re spins. It doesn 't o vercome t he m oment of inertia of a 250 lb . motocross bike right away so t he bi ke d oesn ' t jet forward in a straight line. It d oes set up a twisting to rque o n the swingarm , which flexes an d starts to confuse t he rear shocks. With the rig ht wei ght sh if ts and judicious selection of engine speed , fina lly everythi ng will hook up but u nless yo u're very good , it's lik el y tha t the bike will co me off the lin e o r o ut of the co m er co cked a t an angle an d the front wheel w ill be spi nning in the air a foo t o r two off the gro und. ' T hi s last par t isn' t necessari ly b ad . It's n ea t to cross st utter b umps and ripples with the fro nt wheel floa tin g. Th e works Su zuki riders do it all t he time . But it's hard to t urn a b ik e with th e fron t wh eel off t he gro un d , and d o an efficien t j ob o f it. You see how the co ncep t of the w orks bik es has again just m issed - a more rigid rear frame assem bl y ; a fatter, gra bb ier tire . Almost, but no cigar , on th e p rod uction bike . T he fr ont forks see m t o have m ore usable, progressive tr avel than previ ou s models and wi th the r ight weig h t o il and spring ra te were co m ple tely acce p tab le. T he rear shocks have dual springs of d iff eren t progr ession s. T hey , too, are bet t er in action than before b u t sti ll not reall y up to the tas k. Looks alone will probably se ll a lo t o f the machi nes. They now ca rry the exact paint schem e a nd co nfigu rat io n as the works bikes. The yello w p lastic fenders ar e nearl y as go od as th e n ylo n o nes on th e RN and th e tan k is st eel instead of aluminum all o y . The seat is the same size and shape as a works model and is reall y pretty go od for sitdow n co m for t and co n t o ured for easy m oving aro und. The p rofile- o f th e machine is stre am lined so y ou don't hook your body o n anything. The ri ms are st ill ch ro med steel b u t th e spokes d on ' t loo sen. Except fo r th e too-sm all, to o-hard rub ber on the r ear, the wh eel s, incl udi ng the excelle n t brakes , are go od. What the T M400 is st ill suffering from is the see mi ngly small deviat ions in execu tion co mp are d to t he w o rksm achines. Su zuki has kept the price down . A t so mewhere aro und or under $ 1200, it is th e cheapest, most p owe rfu l 5 0 0 class m otocross bik e you can buy today. But th e era o f cheap ra cin g bikes is over. The co m pe titio n bu yer wants so m ethi ng cl ose to a works machine as a starting p oin t and, ap parently, is willing t o pay for it. Suz uki could capitalize a lot mo re efficiently o n their un preceden ted st ring of mo tocross World Ch ampionsh ips by ad ding ab out .$300 to th e pri ce an d producin g a replica of, say, the RN7 2. Cal l it the TM37 0 or so mething like that. T he weight would be under 220 Ib s., th e d isp lacem en t down by 3 0c c or so, and the sw ingarm wouldn't flex. They co uld d o away with the oil inje cti on a t the same time . It w ouldn ' t really be ne cessary to go to magnesiu m eng ine parts but th at wo uld b e a nice selling point. T he TM400 is really n ot that fa r fro m being "right" as a lo t of publishe d rep o rts wo uld have yo u believe, but it has gone about as far as it Can go in develo pm en t against th e co m p et iti on in tod ay 's m oto cr oss racing market. Any of these changes probabl y depen d mo re on wh et her japan gets the petr oleum prod uc ts 'th ey need from the Arabs tha n or co m petition any market ing mach inery decisions by U.S. Suz u ki o r the j apanese parent com p an y . They obviously have th e potential to o ffer a production World Ch ampionship Replica and th e 5 00cc class would be easier to penetrat e th an th e 25 0 these days. But if you wan t to buy a TM400 today and race it , th in k in terms of ad d ing a flywheel , a good 4. 50 tire, a p roprietary swing ar m and shoc k ab sorbers. It's fas t en o ug h to bl ow off most of th e machinery ar o un d in a str aigh t lin e race and ma in tenance req ui rements ar e m in imal. It 's just ge tting t hat pow er t o the ground , especially out of co m ers, tha t's su ch a hassle. • -., , ~ "..~' . .. Once you got it around the corner, the trick was to point the Suzuki 400 where you wanted it to go, gas it and try to keep it straightened out. The hick of flywheel effect is als o res pons ib le, we think , fo r o ur te st b ik e being a balky starte r . Even wi th th e very good Su zu ki elect ron ic ignition , it was relu ctant to kick ove r. T he c ha mbe r k i c kstar te r-ex pa nsio n relationship have been re designe d so th e leve r d oe sn ' t hi t the pip e b ut yo ur foot st ill does. We tried a rolling b um pstart in second throug h fifth gears with no effect and t he n, j us t on a whi m, tried first . First gear final ly provided eno ugh m ultiplication effect to get the crank spin ning fast enoug h and it lit righ t off. T he experience reinforced our th inking abo ut the lack of flywheel effect. Ironically , th e cold-blooded engin e is ver y strong and very reliable when wa rme d u p p ast the bu rb ling stage . Su zuki mot ors hardl y ever break, quit, o r req uire exten sive main terran ce and th at is a big pl us for any raci ng engine. The power output , whi ch U.S . Su zuki no t es is a few ponies less o n their silence d American im po rt vers io n, is sti ll sufficient to ge t a lot of pe op le inter ested in th e Su zuki engine fo r , on e-off proj ect bik es or m oun tin g it in proprietary frames . If you want to go fast , th e 39 6cc single will propel you beyond what good sense would di ctate. It is fast. And it re ally doesn 't seem to get any w eaker wi th repea ted use. Electronic ignit io n , ad eq uate cooling, and a fine 34mm Mikuni all do their job. The challeng ing part ab ou t riding a Suzuki is when it co mes ti m e to co m er . The b est way to ride it th at we , and a lot of other people , d iscovered is to point it exactl y at th e spot where yo u want to execute y o ur tum. Get on the exc elle n t brakes later t han you th ink a: UJ ~~;i.\t't ~ UJ :J r ...,.,."""''''''~" i =.:;",;,,=-..Q can. Mak e it keep pulling the revs and stay a gear high er th an y o u t hink y o u should b e . You 'll ge t goi ng t ow ard th e next co rn er very quickl y . T he onl y problem w ith this approach, asi de from . the aw kward ness of changi ng d irect ion, is that the front wheel alwa ys see me d to wan t t o go th e o th er wa y fr om what the d irection o f the co rner an d cam ber o f the gr oun d wo uld like. Twist it back around and ge t yo ur weigh t over th e steering head. By fo llowing t his seq ue nce , it was po ssibl e to get th e TM4 00 around in a resp ectabl y quick man ner. If y o u 'r e no t wo rried about making a seq ue n ce o f corners, as you wo uld n 't b e if you were ra ci ng desert or cross-co un tr y, m ost of the problems of ridi ng the Suzuki ar e min im ized . The weigh t of the TM400 is mo st ly up high, though , and this pr obably co m plica tes the co rnering m an euvers even mor e. yo u sh ould to ret ain a speed advan tage because yo u ' ll need the extra t ime to get the direction of t he 25 0 lbs , chan ged. T he brakes ar e first rate o n the TM4 00 . They ha ve a ,m ore p rogressive feel and aren't prone to lock-up as ar e some ra cing Yamahas. T hey are fade -free and brin g y our speed d own in a con tr ollab le manner until th e re ar end star ts to lift o ff th e gr o und and hop arou nd . Whe n you get to y o ur co rneri ng spot, execu te a ki nd of aw kward little dan ce to haul t he bike around to where you want to p oin t it next. There are very fe w riders w ho co uld sm oo th o ut th is maneuver . It was mostly a matter of t hrowi ng it over and yanki ng it aro und with t he inside foot p lan ted . When yo u 've go t it pointed in th e di rect ion yo u w an t to go n ex t, hang on an d twis t the t hrottle grip o n sm oothly. T he n start sh ift ing up as q uick ly as you Tank/seat profile was smooth; movement easy. Little breather vent gizmo fascinated testers. Acceleration over bumps always produced the same result. The front end would come up. z « ~ C UJ Then the rear end would come up and start hopping from side to side. r u a: .J u. a: :J I- r a: « 396cc of rompin', stompin", horsepower that is only partially usable. Z c ., z r « ~ ~ C a: UJ :J a: .J u, z Ia: a « ., r 41