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/125859
The reigning champ of the 500 tou a. ~~::j. 5 u IL..;b---!::; o ~ .. :r: !d a: oJ ~ z :r: o , : ... - Both machines are for going places a n d both will cost you a little less than a gallon every 40 mil es to get there. Four cylinders prove better than two. Th e reignIng king of th e " 50 0 " class is t h e Honda CB55 0, an d t he only seriou s fo ur-stroke challenger to com e along lately is the Yamaha TX500A. We rode them several thousand miles each in Southern California ... between home and work, from home to 48 rural picnics, and on longer pleasure rides. In short, we used both bikes the way we. use OUf own motorcycles for going places. The Yamaha an d the Honda share some of the same characteristics. both having four strokes, eight valves, wet sumps, electric starters, five speeds and two wheels. From there the diversity begins. The Honda is a single ove rhead cam, in-line four, while the Ya maha is a dual overhead cam, in-line twin with four valves per cylinder. The four chugs along m o re smoothly at low speeds than the tw in , even though the Yamaha owner's manual speaks of " th e kind of smooth, effortless lugging ability that o nly a 4-stroke can provide." Later the same book warns "Never lug your engine!" It goes o n to say never operate the engine below 3,500 RPM, and even later still, (in the break-in instructions), demands that the owner not exceed 3,500 RPM for the first 300 miles. Ergo: hold the throttle at exactly three and a half grand .. . if you can. If Ya maha buil t the TX500A to give the customer "effortless lugging ability" they m issed comp letely. It will not p u ll an inch be low 3,000 RPM, and fee ls like an anemic 175 below 6, 000 RPM . The H o n da , on the othe r hand, wi ll glad ly pull fro m abo ut 1,500 RPM and clearly runs st ro nger than the Yamaha b e l o w 6,000 R PM. T he Honda's p owe rb an d was nice and smooth from idle to the 9,200 RPM redline. What the Yam ah a did splendidly was come on the cam at over 6,000 RPM, taking off with a strong surge from 7,000 RPM up to the 9,000 RPM red line. The Honda's power characteristics were those normally associated with a four-stroke, The Yamaha's were more li ke the characteristics of a two-stroke. The eight-valve he ad with two cams and very short ro cker arms was designed for good high RP1\1 breathing, not low RPM lugging. I t had to spin higher to do the same work, relative to the Honda. As a result, the Yamaha averaged 42.6 :'IPG to the Honda's 44 .5 MPG during our test. In a rolling start drag race over a quarter mile, the Honda won by a half length even when the Yamaha 's r evs were kept up. In a 40 MPH fifth gear roll on, the Honda won significantly, walking awa y from the Yamaha after overcoming an engine burble caused by inaccurate carburetion. The: Yamaha's lack of pulling power below 6,000 R PM really showed as the CB550 gai ned an d held close to ten lengths from 40 MPH up to 100 MPH. Raw power characteristics aren '( all there is. Imprecise carburction and d rive train snatch conspired to make the TX500A a motorcycle you had to work at riding, instead of just riding. It was a jerky horror in stop and go traffic, and didn't reel much better on the frecway. The carbs a re the same constant velocity Keihin models that give the Honda 450 snat ch problems, only the pair on our test bike were not as well sorted out as the ones on most Honda 450s. The way it was, you just couldn 't ride the Yamaha at a constant speed. The slightest movement of the twist grip wo u ld produce a lurch, either throwing t he rider's head fo rward in a snap of deceleration or whipping it ba ck as th e engine took up slack in the final dr ive system all at once , I t was the same story on the freeway - it didn't m at t er who rode it. everyone remarked on the difficulty or riding at onc speed smoothly. (T h e Yamaha manual sa ys, UDo not o pe ra te it a t one set throttle position" during the first 300 miles." You carr' t. ] It was impossible to set the throttle at one set ting and leave it because the throttle drag control didn't work. The Honda was easy to ride in traffic, but had a flat spot right at the 5 5-60 MPH cruising speed now needed on the freeway. Any a tte m p t at acceleration in th at range produced a burble but no go until after a bit of hesitant gagging. It was possible to ride at a constant speed on the Honda. however, and the throttle drag can trol held it well. To go with the snatchy power, the Yam ah a had a snatchy rea r brake. The fro n t dis c was excellent - extremely p owerful, controllable, and reliable w ith n o fading - but the rear was impossible to apply for cefully without locking it up a t normal speeds. In emergency Yamaha instrument cluster at least had the key position wh ere it should be - in fr ont o f y ou. Rear brake lini n g warning light was an extra goodie . situations it was instant smoke at the rear wheel because the fine line be tween maximum braking force and loc ku p could no t be found by most tes ters. Joe Biker is going to have a hard tim e using the Yamaha's rea r b rake. The brake was a rea l hazard if you tried to usc it lat e c o m inK in to a turn becau se the locked-up rear e nd w ould p u t you inro a hairy slide. 1\ passenger's weigh t on the rear whee-l prevented this from being such a problem. The Honda rear brake was not as powerful nor as sensitive, with the result th at it was easy to use ann worked bet tee . The Yamaha front disc brake delivers more mechanical advantage at the caliper than the Ho nda, resu ltin g in more stop ping p ower wi th less p ressure . T h e Honda calip er has a hydraulic p iston o n one side an d a fl oa ting puck on th e other side .o f t he d isc. T he Yamah a has a hydra ul ic pi sto n p ush ing b oth pucks in the cal iper. T he Hon d a d isc re quired m ore pr essu re to do the j ob, b ut still did it wel l. It was less n erve w ra cking stopping th e Ho nda in a bu rry because it did not pull a ny su rp rises t o distract one from get t ing st opped. T h e di scs o n b o t h bik es squealed: the Yamah a 's e m ilied a sharper noise than the Hond a's. Where th e Yamaha's power and braking seemed to put it together was above 60 MPH on a twisty-tumy road . At tha t speed the rear brake didn't lock so easily, and the engine/drive train combination was not so snatchy. Too bad you can't go that fast many places anymore. With the Honda. it was not necessary to t ravel very quickly to m ak e e veryt hing smooth. It delivered smooth power and braking at all times , excepting the 55ยท60 MPH flat spot. T he Honda handled better than th e Ya maha, wh ich had to be force d in t o turns when ridden fast. More ra ke and lo nger trail make the Yamaha want to keep goi ng straight, compared to th e Honda. And once it is stuffed into a tum , it has a tendency to fal l into th e turn because of a higher center of gravity. Ironically, the Yamaha has more ground clearance in corners than the Honda, yet it was easier to go fas t in turns on the CB550. When forced into a high speed sweeper, the Yamaha would oscillate just enough to make you worry without actually getting dangerous. The Honda was always rock steady. When riding the Yamaha over concrete freeway expansion joints, your stomach at times rattles around so much it hurts. Your kidneys either cu rse the non-suspension or pray for a kidney belt no matter what position the shock pre-load is set on. The shocks just do n o t take up little jolts and the b ike feels like a rocking horse on bumpy sections. The Honda had a better ride; the rear shocks on th e CB550 worked, and the Honda felt steadicr than the Yamaha on rain grooves, While it lookcd good, the Yamaha seat just was not as comfortab le as the Honda's. Both h ad plenty of padding, Honda's dials and lights were m o re compl ete and seemingly be tter designed. but one was too hard and too n arro w for long trips. The Honda 's seat was fine. The TX500A has a chain-driven, Omni -Phase Balance to smooth out the vertical twin vibes, but still ran rougher than the Honda . Compared to m ost twins, the TX is indeed smoo th, but the Fo ur is just smoot her. Mos t of Yamaha's vibration is F t in t he bars, el b ut not enoug h t,., be bothersome. The instrumen ts on the Hon da are the sa me as the Honda 750 has, and are the best in the industry. T he Yamaha's are m ade by the same company and are almost as good, but ar e harder to read both day and night, especially the reset table trip odometer. useful for keeping tabs on how far you've gone on a fill up . The Yamaha's speedometer len s fogged up from condensa tion. T he Honda 's speed a was very opti mistic.