Cycle News - Archive Issues - 1970's

Cycle News 1972 06 13

Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles

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..:! ." LIGHTWEIGHT REVIEW '" .... YAMAHA ATM: SHOESTRING Mler 0. N C'l No.1 in a Series M " .., " c: ~ w Z W ...J U >U ,, By Jo hn Hu er ter and the CN Staff For the kickoff m ach in e of the CN lightweight test series, it 's hard to name a better candidate than the. Yamaha 125 . It see ms as though at least half of any small bore racing class, whether rno to cross, desert or scrambles is made up of the Oriental imports, in various states of tune. modification and repair. What makes the Yam ah a so popular? Ho w does a hopped-up version of a dual purpose machine command so m uch of a Iigh tweigh t market saturated with high performance 125s? Particularly with the less than sterling Ya maha rep u tation for handling. What about the AT2·1\1X, anyhow? Well, fo r openers, it's probably the cheapest ,way to go racin g, and bro th er , m o ney ta lks . At a suggested retail of $603 , m o ney says " Y amah a!" to a lot of race rs . In evaluating th e Yamaha, th e op inio ns of a road rac er (H mm?), a h o tsh oc mo tocr osser , a desert rider an d a beginn er were so licited. Wheth er it was used as a pit bike or l\lX er, every o ne of th em lik ed it . Ya maha is likely to pick u p a sale t o a co u p le of th e tes te rs . T he re is one gian t th um bs do wn on th e 12 5 Yam . They sh o uld n ot m ark et it with o ut a silen cer. The 250 an d 36 0 MX m ach ines h ave pretty good o nes . Why n ot the 125 ? As an out-the-door playbike, even an in exp en sive on e , it sh ould be silen ced. Particularl y sin ce beginner racers and riders ar e lik ely t o buy it. The beau ty o f the Yamaha stems from the co re of the machinery: a tractable , well-carbureted dependable engine, this year featuring a reed valve. The engine is fairly peaky and older 125 AT-2 motocrossers loaded up if y ou let th e revs fal l below four or five grand. The 1972 AT2-MX allowed you to downshift, wick it once, and it was cleared and you were go ne . We'll attribute this sw ell behavior to the reed valve . It works. The peakiness of th e engine didn't bother either beginner o r advanced rider, it see med to fit the riding styles of a lot of motocross riders. It is also super easy to start: first kick with th e richening lever dep ressed and a little thro ttle. It was n't hard t o keep the engine in the powerband with an y of five speeds to choose from; one wa s right for mo st any situation. Shifting was perfect fo r all excep t one rider who tested it. Most never experienced a missed shi ft. It is super smooth with a very short throw and posit ive snick into place feel: one down , four up on the left side. Yamaha transmissions have a pretty decent reputa tion fo r longevity , co n side rin g that Yams are often a first bike and subjected to some abuse such as clutch !ess st omps. Our AT2 shifted with or w ithout clu tch and w as pure p leasure to use . Most every b ody wh o rode th e bik e int ensively th ought th e combination of b ox and p ower were gre at. One thing every body was impressed with w as th e speed. Cet th e little bugger singing and it is fa st . Wh oopee. The induction sys tem seemed to be meterin g well and p ower felt sp o i o n . with a B8EN plug; a pl ain o le B9 fouled. The Yamaha has su ch sp eed th at it probahly wouldn't be giving away much top en d to bigger bike s on a sh ort co~rse . Some / -. -~ - . -. -- - - ,....,- - .. -- Handling was surprisingly good . You can lean it over and hold a line. rid ers migh t w an t to gea r it a li t tle lo wer t o force th e R's up , b ut that is lar gely a personal choice based o n th e sk ill factor of the rider. Handling was surprisingly go od. Everybody expected some kin d of p o go stic k full of unwanted surp rise s bu t the opinions of most riders go t rev er sed af ter a few hot laps. The fr ont end would not wash out. Perhaps with some help from the 21 -inch fr ont wheel which was previously an extra but is now a standard fix ture on th e model. The 3. 50 X 18 rear is another go od choice fo r the AT-2 . A 4.00 w ould probably be too rough on th e clutch, among other things me chanical. Leaning it over into turns w as usually a pleasant experien ce. It would sweep Mikuni 26 mm has reed valve to go with it, is rubber-mo unted. around th e comers, tracking on any ch osen lin e. It worked be st with th e vulnerable for o ff-road o r MX. The simple design and so lid co lo r work engine really humming and a fai r fr ont on e crinkles in y our hand. together. amount of power getting to the ground . The 125 has a really great, That seat we lik ed so well flips up, It does n o t feel shott-coupled like some well-padded , h eavily grain ed seat very like on the enduro models. to service 125s and th e longer wheelbase helps m uch like th e ones on its big b rother the air cleaner, add oil, e tc. T hin k ho w treme ndously in leaning it over with out mo tocrossers. Boy, it was swell. The convenie nt that is compared to a lot of breaking lo ose. The Yam als o assumes a sea ting position mi gh t b e hi gh fo r a rno to c ross machines. good natural position goi ng over jumps really sm all rider b ut for 5 '6 " on up , it 's A se t-up of the 125 Yamaha rnigh t and will lan d slightly nose up if y o u give ' OK. The carb ure tion is via a flat-black include a fiexo-fend er up front, . new it a ch an ce. 26mm Mikuni which is reed-valved, shocks and so me stiffer fo rk springs. For- co mp eti ti o n , the 'bars an d sto ck and just lo ok s With tha t, and only th at', be prepare d to rubber-mounted grips are imp ractical. A moto cro ss o r bu siness-like as hell. I t is ni cely give a good acco un t o f y ourself in the desert ra cer would probably want to waterproofed with an amp le rubber 125 class. You ride the little beast a replace them; almo st everybody does du ct fr om the fo am fil ter in the still air while and y ou understand why half th e when they go racing. The fro n t fork s box . Tank cap acity is ample an d the Iigh tweigh t brigade are on them. co u ld st and a little help since th ey are the same , even to the triple trees, as the enduro forks. They are good , but can b e better for all-out racing. The sh ock s, well.i.they' re Yamah a sh ocks. You probab ly know wh at brand su its y ou best. If y ou're going to us e th e 125 for much more than a pl ayblke, buy a set. Detailin g on the Yamah a is a mixed bag. The st reet bike-style gas ca p is aw kward to o pen and close , p articularl y with glo ves on, bu t it d oesn't leak so, o n balan ce , ca ll it good. The fend ers are identi cal to th ose on the enduro m od el (You can 't fool anybod y just by in creasing the clear ance. ] and wa y t o o .~=:...: Sty'ling sells mo to rcy cles, Yamaha knows styling : Yamaha sells bikes. MORE THAN YOU PROBABLY WANTED TO KNOW ABOUT THE AT2-MX: Seat flips up afte r a single catch is released allow ing access to any thing you might want to get into under there . Horsepower @ RPM 20 Bhp/8500 rpm Torque @ RPM : , 12.3 ft-l bs/8000 rp m Bore & Stroke (m m) : 56 x 50mm Engine Displacement 123 cc 92 Kg (2 03 lb. ] Net Weight (appro x.) Air Filter Type Wet Foam Rubber Primary Reduction Ratio & Method 74/19 ge~r Se condary Reduction Ratio & Method 45/14 cham Trans. Cear Ratios 1st (In tern al) _ 2.833 2nd 1.875 3rd 1.3 68 4th 1.091 5th , . . . ..... . . . .... . •.. . . . . . . 0.956 Trans. Oil Capacity (Qt.) ( typ e) ; _ 750 + 50cc Oil Tank or Engine Sump Capacity (Q t. ) ( typ e) 1.3 q t. Fuel Tank Capacity (U.S . C al.) (o ctane rating) 1.8 gal . Front Fork Oil Capacity 120cc Tire Size (Front) (type tread) , -;' 2.75-21-4PR (re ar ) (type tread) . .'. . ~~ ~ ' .".r: ~ .. ~;; ..' : 3.5 0- 18 -4P R

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