Cycle News - Archive Issues - 1990's

testers did occa s io na lly co m p la in of mi ssing more s hifts on th e Kaw asaki. The clutch on the Yam aha will fad e.with abuse and see ms to have a sho rter life span, from wha t we've heard (altho ug h we are still on ou r origina l clu tch after three m onths of hard ab u se). But, as we' ve said a few times 'before, if yo u' re abusing the clutch on th e YZF, you ' re riding it like a bozo. One thing w e n ot ic ed a bo u t th e YZ400F is that a lot of riders hav e trouble with stalling the motor goi ng into corners . It doesn 't cough and di e - it just dies sometimes if you let the revs drop too violen tly and don't pull in the clutch fast enough. A few of our riders (the on es w ho have ridden four-strokes before) never experi enced this problem, and we think it's just one of the differences that you've got to learn to d eal with. Wit h a sta ll co mes refiring the 400, and tha t's where thin gs got a little u gly. The two-s troke regu la rs ju s t weren' t quite up to speed on the starting d rill and wo uld spe nd about a minute kicking it, w hile a sim ila r stall on the KX . wou ld only cost you about 10 seconds. Those laps were thrown out of the lap sheets, bu t it happened quite a bit with the 400. The bike starts fine hot or cold as lon g as you remember th e routine: Find top d ead cen te r (the hard spot), p u ll in th e co m p ressio n rel ease a n d m ov e th e kicks tarte r d o wn abou t a n inch, and then give it a hard kick wi th no throttle applied . It's easy enoug h to d o, bu t there is no doubt that it will take you lon ger to sta rt the YZ in a p a nic tha n it will the KX. . Suspensionwise, these bikes do a n ad mirable job of han dling track irreg u larities, although some of our tes ters (especially the hea vier or fas ter rid ers) felt that both bikes could use stiffer fork springs . Wi th 95 to 100mm sag in the rear, bo th shocks wo rk excellently, provid ing p lus h ac tio n, contro l and a good resistan ce to bott oming. The KX is the plu shes t 250 out th ere, but th e YZF is s till e ven m ore plu sh over s m a lle r trac k irregularities, probably du e to the 30 extra pounds and the nature of the four stroke power deliver y. The YZ tracks a little better because of this, but because of the extra weight, it jus t can ' t quite hang with the KX in really deep whoops wh ere the KX' s in stant power and lighter weight make it easi er to skim across the top of the whoops. Landings from large jumps, especia lly into holes on flat gro u nd, are al so slig htly more confidence-inspiring on the KX, d ue to it s lighter w e igh t. All of o u r tes ters agreed that you just see m to slam down a littl e harder on the YZ F, w hich is a tad unsettling 'w hen co m pared to makin g the same landi ng on the KX250. Fast, flat and slick turns were dominated by the 400 due to the sm oo th and tractable na ture of the power d elivery. You can simply apply the gas soo ner on th e Yamaha, and most rid ers felt an increase in midc orner and exit speed in nearly every situation. The only corne ring situation w he re the Kaw asaki felt markedly better was in extremely tight a n d sa n d y turn s, where th e lighter weight and instant power are the necessity. Both of the bikes will exhibit mi nor hea ds hake if you chop the throttle coming into rough an d chop py corn ers - bu t w ha t b ike d o e sn' t in th es e ci rcum stances? Braki ng performance was admirable on th e pair of mo tocrossers . The KX fro nt brake did get a little mushy with time and n eeds to have the fluid cha nged and bled eve ry once in a w hile to combat this. Some riders also wan ted a little m ore p ower out of th e fr ont bi nders on the 400 F to d eal with th e extra weight of the bik e, but conversely, so me of our testers thought the brakes were perfect and felt the y could actually brake lat er and deeper into turns on the Ya ma ha. This s tr u c k s ome of u s a s stra nge, because th e YZF d oesn 't have a s mu ch engine braking as a regular four-stroke, with its light flywheel and cra nk and high -revving motor . We think it may just be a mental thing: Since it's u su all y easie r to d eal with corners on the YZ anyway, ma ybe riders we re coming into th e turns hotter du e to newfound cornering confidence. Hey, whatever works for you , rig ht? Sitti ng on the du o re vea ls an equally sli m, flat a nd comfortable rid ing pla tform . Most of our test ers prefer red the flat and soft seat on the KX, as we often heard minor complaints about the hard and pointy Yamaha throne. With all of th ese poin ts in mi nd, it should be very easy to see tha t each of these bikes has its own set of streng ths The KX250 motor (above left) produces an explosive , bottom- to midrange-based s pread of power. The VZ400F four-stroke powerplant (above) has a good spread of power from top to bottom, but things really start happening In the middle and upper rpm. Both motors are very potent. (Below) The KX250 (6) and the VZ400F (19) are both very pred ictable in the air. The YZF is better at takeoffs, especially when they are rutted and s lick, while the KX Is better on harsh landings beca use it's lighter. and weaknesses that, for the most pa rt, match the weaknesses and strengths of the other bike. It's alla trad e-o ff. Tes t rid ers who had spent mo re time ge tting acclima ted to the fo u r- stroke a nd its ways turned in lap tim es that w er e almost identical to those pos ted on the tw o -s troke between the th r ee tra ck s, while the testers who pri marily rod e two-s trokes turned more consistent and faster lap times on the two- stroke KX. If mos t of us had been ridi ng four-s trokes for the las t 20 yea rs , it wou ld be th e other way around, for su re.

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