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/125864
YAMAHA MX 175 5 • e c ea a ost-racer By Charles Clayto n According t o rule-of-th um b, the optimum SIze engIne fOJ; a motorcycle rider should displace approximately one cubic centimeter per pound of rider weight. By this standard, the yellow Yamaha I 7.') MX, at 171 cc should fit the majority of people. And it docs. Taking hold of the handlebars and gripping the seat with your knees, it feels like a smaller bike , more on the order of a 125 . It is. light enough to be flung about, using the bumps and grinds and hip-slings that m oto cr osser s employ , and it will dance all over the track like a good partner. Where you lead, it follows . The aggressive engine is tuned to develop most of its power in the top few hundred RP~1. It is a racing motor, not a slogger. You bu zz it high o ff the line and feed the clutch in caref ully, balancing rear wheel slippage with the desire of th e ligh t front wheel to come up and you stay crouched over the handlebars until the chain is pulling well on the pipe, while punching the kill button and kicking up higher and higher gears until your land speed equals the pull. Then rock. well back on the pegs , keeping th e throttle on and your knees bent, steering with body English and those sudden slings like some jersey ed adagio dancer, That is the \vay to ride the Yamaha 175 MX , After a few laps around the old MX course you learn which gears you have to be in to keep the speed where you want it with the throttle pegged on that narrow power band, and you start to evaluate the handling, Frankly, it needs help . The forks and shocks are not up to the job on a rough course. We didn't have the Yammy long eno ugh to experi me nt w ith fork oi ls and shock un i ts, so we co mpensa ted by hanging ou r buns we ll off the back of the seat an d try ing t o un icy cle over everything. This sty le fo rced the rear end to its limit and almost convinced us that the hand ling was unsu it ab le for over- 150 lb . riders. Better (Betor?) shocks and thicker fork oil migh t he lp . T he stock s hocks worked fairly well until heat-fade set in. And the forks seem to have plenty of travel. It's just that it's all taken up at the first rise in the real estate and then the handlebars start rebounding wildly. Turning smooth corners the handling was sp lendid. It wou ld go in very fast and come out straight just by unconsciously leaning in the desired di rection and then allowing the machine to come back vertical. Turning was quick, owing to a combination of 53 inch wheelbase and short trail, but there was never a no t iceabl e tendency to pivot around the front wheel axle: • Starting was easy, one or two kicks against fairly high co mpression, and the Mik uni carburetor lets t he motor idle for h o urs without loading up. However if it is ridd en below the power ra nge for any time, there is a rather lo ng wait fo r th e scavenging to ove rco me a ric h mid-ran ge mixture and clean ou t enough' to cli mb on the p ipe , Her e is wh ere the easy-sh ifting gearbox and its five nicely-sp aced speeds are appreciate d . Re moving th e Autolube and running 40 : 1 premix w oul d pro bably make it respond better. T he exhaust pipe cracked at the stinger during o ur field test. It bulges in the way of getting at the carburetor slide . Brakes, fenders and co n troIs are up to m o to cross standards. The Yamaha 175 MX impressed us favorably. It nee d s the usual sorting-ou t and attention to setup and maintenance, but 00 ....... we c an re commend it to medium-weight racers who want to go fast for not a lot of money and who will ap p reciate a MXer that is basically all there. Oh, did we remember to say it's fast ? • The 175 will fit a lot of would -be budg et racers. Thermal Flow shocks need the standard re-wor king (Fresh damping fluid for openers.! Spec ifications Turning radius Wheelbase Ground clea rance Fro nt tire Rear tire Engine Torque Ignition Weight 75" 53 " 10" 3.00x21 3 .50x18 Reed valve , 7 :1 c.r , 11 .1 ft . Ibs. @ 8500 C.D.I. 18 5 Ib s. Parts Price Light weight, short wheelbase and peaky power equal s - wheel ies! Points _ Condenser , Throttle cable Clutch cable Front brake cable Rear brake cable Air cleaner element Rear brake linings Front brake linings , . , • • •. Clutch plates , Fork seals, each Drive chai n, stock .. ..... . . . . .. .. Head gaske t Base gasket . ... ...• . . . . .. ..... . Pisto ns, eac h ,.. Wrist pin, each Rings, each set Cirelip s, each , , $3.50 $1 .72 $7.00 $3.08 $3.04 , $1.10 $5.20 $2.60 • • $1.80 $1.80 $1.98 . • $9.20 $.95 . • . $ ,15 $ 14 .5 0 . • $ 1:7 5 $7 .25 $ ,10 Mucho power emerge s from a Yamahareliable engine, "The 175 Yamaha corners qu ickly and wants lots of RPM to sling it back out along with a little body English . l/l > <{ o "' a ": o "' o >ell l/l o f- '--_, ~ 37