SUS­PEN­SION

Dirt Rider - - Gear Bag -

Yamaha moved the ra­di­a­tors, shrunk the gas tank, and re­designed the shrouds in an ef­fort to slim down the bike to the tune of 16mm nar­row at the shrouds and at the “pocket” of the seat. The new air­box and fil­ter are still tool-less, now with one Dzus fas­tener for the cover and clips to hold on the fil­ter. The seat is 8mm lower at the front and 19mm lower at the rear. Com­bined with the taller bar mount­ing, one test rider felt the bike was a lit­tle “chop­pered out” un­til he rolled the han­dle­bar back a lit­tle. The bar bend is the same but the bar is lighter, and the rims (they are blue on the blue bike) are lighter too.

Yamaha put Wi-fi on the bike and its power tuner on your smart­phone (just down­load the free app). The ad­just­ment grid is now 4 x 4 in­stead of 3 x 3, and the tuning val­ues can be ad­justed to fo­cus the tuning to a nar­rower rpm range. Fuel is ad­justable richer or leaner up to 14 per­cent, and ig­ni­tion can be re­tarded 9 de­grees or ad­vanced 4 de­grees from stock. Rid­ers can quickly pick from three stock maps, cre­ate their own maps, share maps, and try maps that the Yamaha test team shares. For para­noiacs wor­ried about their bike get­ting hacked or a trans­mis­sion in­ter­cep­tion, the app is pass­word pro­tected, only two phones at a time can be tied to any given bike, and the bike’s sys­tem must be pow­ered up but with the mo­tor off. The tuner also has a race log to or­ga­nize your best set­tings.

Even the sus­pen­sion got some up­dates. The fork’s cylin­ders and pistons are up 1mm to 25mm, and the mid-speed valves and pistons are up­dated. The shock’s sub­tank ca­pac­ity is in­creased 30cc, and its spring is lighter in weight and one rate stiffer (from 56 to 58 N/mm). The fork rate re­mains at 5.0 N/mm.

EN­GINE

With 450cc of dis­place­ment, a bike in this class can have too much power, and that was a crit­i­cism of the pre­vi­ous-gen­er­a­tion YZ-FS for some rid­ers—maybe not too much but “too much too soon.” The 2018 ma­chine does a bet­ter job of mak­ing that horse­power more us­able with­out mak­ing it less po­tent. Yamaha has smoothed not just the off-idle hit but also the full power de­liv­ery up through the rpm.

Nearly ev­ery rider com­mented the power down low was strong, but more im­por­tantly it was ac­ces­si­ble and no longer abrupt or overly snappy. The smooth and tractable feel­ing con­tin­ues through the revs, mak­ing the bike easy and fun to turn with the throt­tle in the flat cor­ners and also mean­ing rid­ers could rely only on throt­tle in­put and leave the clutch alone in cor­ner ruts.

The over­all char­ac­ter of the power still

re­tains some tra­di­tional four-stroke per­son­al­ity with a trac­tor-y feel­ing com­pared to some of the other bikes in the class. It’s one of those de­ceiv­ingly strong en­gines where you might find your­self launch­ing far­ther than the rpm sug­gested you would. The most us­able por­tion of the power­band was the low to mid, yet some testers com­mented the bike needed to be shifted a lot for a 450, with first gear be­ing es­pe­cially short. Yamaha has held the top spot in sus­pen­sion ac­tion and feel for about a decade, and blue shows no signs of mak­ing a mis­step. Yes, the 2018 YZ450F has out­stand­ing sus­pen­sion.

Prob­a­bly the best word used to de­scribe the sus­pen­sion feel is “but­tery.” The Yamaha makes the small track im­per­fec­tions dis­ap­pear and gives al­most a magic-car­pet ride over the chat­tery stuff. More great news, many testers felt the bike needed no ad­just­ments to make the sus­pen­sion feel just right for them; the stock set­tings suit a wide range of rid­ers.

There were, how­ever, two pro-level testers who com­plained of a harsh­ness trans­ferred to their palms, with one say­ing he also felt a mid-stroke step in the fork. These same pros felt a sort of “bounci­ness” in the fork at cor­ner en­tries. These two crit­i­cisms were al­most lost, how­ever, in the list of praises for the sus­pen­sion feel, as most rid­ers, heavy and light, novice to ex­pert, felt the bike was plush and also han­dled the big hits amaz­ingly well.

The YZ-F has a sit-in (rather than sit-on) feel­ing that al­lows the rider to feel a part of the bike; it’s more of a ma­chine the rider charges around the track rather than fi­nesses, ma­nip­u­lates, or man­han­dles. The pre­vi­ous YZ450F had a very big and some­times un­co­op­er­a­tive at­ti­tude; this new bike is much more ea­ger to lis­ten to the rider. It’s lighter feel­ing on the track, and some rid­ers even said it had a 250-ish feel, though it still has some of that “sig­nif­i­cant” feel of the pre­vi­ous bike.

But the big YZ-F did draw some han­dling crit­i­cisms of head­shake at cor­ner en­trances from a few testers, while oth­ers felt no trace of it. It was mostly lim­ited to a twitchy front end un­der brak­ing when en­ter­ing high-speed cor­ners. One pro tester had a big prob­lem with this, but a sag change down to 107mm then go­ing two stiffer on fork com­pres­sion and four slower on fork re­bound reme­died the prob­lem. An­other lighter, fast tester cured the cor­ner-en­try twitch­i­ness by go­ing just three clicks slower on fork re­bound. There was also a few men­tions of a front end that wanted to climb out of ruts or just give a vague feel in cor­ners.

Most rid­ers felt they could put the bike right where they wanted on the track, with com­ments that it rolled well through the cor­ners, that it had a calm, pre­dictable na­ture, and that it had great sta­bil­ity on straights and jump launches. One pro rider even said the bike al­most seemed to adapt to him and the track con­di­tions, ne­ces­si­tat­ing no sus­pen­sion tuning.

All our testers felt Yamaha’s new slim­mer body­work was a great im­prove­ment, though some wanted it to be even thin­ner, and many felt the bike was slim and great while stand­ing but once sit­ting to cor­ner the shrouds pushed their legs out too far. One rider found the left header in­ter­rupted his grip on the bike, while an­other felt the bike’s sides had an over­all slick feel­ing and would use grip tape if it were his per­sonal bike.

The clutch was praised and the Yamaha is a clean-shift­ing ma­chine, and the brakes were loved for be­ing strong and easy to mod­u­late.

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