Post by Pardee on Jun 25, 2014 13:22:40 GMT -5
THE LONG DISTANCE RUNNERS
A Comparative Evaluation of the Top Touring Bikes
BMW R/75 /Honda CB 750 / Kawasaki Z1 / Suzuki GT 750 / Triumph T150V / Yamaha TX750
YAMAHA TX750
Several years ago the largest bike Yamaha offered for sale was the 350cc two-stroke twin. Their entire line was comprised solely of two-stroke machinery. Of course being interested in selling motorcycles Yamaha decided to enter the market with an overhead cam 650 twin four-stroke for the "touring" rider. However, in our estimation, the 650 leaves a lot to be desired as a touring or performance bike. In some aspects the XS1 was better than some other 650's kicking around at that time. However, it was not without its drawbacks, such as poor handling, excessive vibration, and poor braking. The updated XS2 was fitted with a disc brake, which improved the stopping ability considerably, however it was still plagued with handling problems.
When we had the opportunity of doing the first test on the 750 Yamaha last year we did not rule out the possibility it might only be a bored out, updated version of their 650. It wasn't though, and we were pleasantly surprised. Yamaha started with a clean piece of paper for the TX750 and designed a machine that was completely new from the front to the rear.
The TX750 is the only Japanese bike we know of that offers the buyer aluminum rims both front and rear. The disc brake (from last year's 650) has been redesigned and its both smooth and powerful. After many hard stops the brake didn't exhibit any tendencies to fade.
The hydraulic leverage Yamaha has built into their disc brake is considerable. It is necessary to touch the lever with only one finger to initiate noticeable braking response. At the higher speeds this type of leverage is a welcomed asset. However, at the slower speeds, if one isn't extremely careful, it is possible to lock the wheel with hardly any effort at all.
Because of efficiency of the front brake and the average performance of the rear we were able to get the TX stopped in third position in both panic stop braking tests. In one instant during the 35 to 0 test we had the front wheel lock solidly, and start to turn under. However, quick reflexes and a relatively stable motorcycle saved the situation and let the rider remain in the saddle.
It was quite evident that there is a great amount of weight transfer during any kind of stopping activity. This was obviously due to the exceptionally soft suspension that is fitted to the TX. Both the front suspension and the five-way adjustable shocks offer an extremely comfortable ride. This type of suspension was adequate only if we ran in a straight line at speeds of 75mph and less. Unfortunately if you gas it up now and then you will immediately notice that the comfort asset of the suspension immediately becomes a handling shortcoming. At speeds of 75 mph the machine acted as though it were riding over miniature rain grooves. We do feel that this behavior is a design fault of the machine that can and should be corrected for better handling.
We were disappointed with the cornering of the TX. When rounding a relatively fast corner (70 to 75 mph) that requires more lean angle than the average freeway corner the bike begins to twist and wobble. We put the blame on the soft suspension. Also there seems to be a bit more weight sitting up high than we consider prudent. This adds to the tendency to wiggle. Anyone who has experienced this on the XS2 will be relieved to know that the TX is no where near as violent.
Unfortunately to many designers seem to exhibit tendencies of favoring one extreme or another rather than striking a suitable compromise. We would like to see suspension components that fall somewhere between the ultra-stiff Kawasaki Z1 and the extra-soft TX750.
In evaluating the TX's performance around a slow corner it is necessary to consider the torque characteristics of the engine as well as the suspension. The throttle response on the TX proved to be the best of the six bikes we tested. However, this good response actually seems to hinder cornering at low speeds. Because of it the bike seems to right itself a bit. However, we were able to adjust to this behavior.
The TX, as well as some other Yamaha models, comes fitted with a hydraulic steering damper. It is interesting to note that during a test with a 350 Yamaha we removed this hydraulic damper and didn't notice any adverse affects at higher speeds. It was quite stable actually and we definitely did notice an improvement in low speed handling.
In an effort to reduce vibration Yamaha has installed a pair of contra-rotating weights at the bottom of the powerplant. These weights are chain driven so it is conceivable that their timing could be changed to dampen vibration at any spot in the power ranges. While the vibration on the TX wasn't great enough to cause a considerable amount of fatigue it did at times cause our fingertips to go numb. But even so it is perhaps the smoothest vertical twin that we have ever tested.
The single overhead cam engine itself offers nothing unique. Its layout is rather conventional. The engine is redlined at 7000 rpm. We found that figure to be the optimum shifting point for maximum performance. The TX features a five-speed gearbox.
The clutch is a conventional wet multi-plate design. The clutch operation was exceptionally smooth. Only the Honda required a lighter pull on the clutch lever. Engagement occurred slightly past the mid-point of travel.
On the first TX we tested last year we had some problems finding neutral at a stop. The unit we tested this time exhibited the same trait. We found it best to select neutral before coming to a stop.
Yamaha's positioning of the rider contact points is satisfactory. The handgrips which bow out in the middle and get slimmer at both ends, are better than most. The seat seemed just a little too narrow, but the firmness seemed right for putting on miles. As we mentioned the TX is plagued with some vibration. The footpegs transmit this vibration to the rider.
Yamaha has incorporated a few new features on the TX, as well as some other road models, that would possibly bewilder a Sopwith Camel pilot but do offer information to the rider. There is a small switch located on the rear brake backing plate that is opened if and when the brake lining wears past the safety point. This activates a warning light on a very impressive instrument panel. The rider then has two choices as far as deactivating the warning light. He can replace the brake shoes or he can be stubborn and cut the wiring.
We really liked the rather unique reserve lighting system, in the event that either the high beam or low beam circuit is broken for any reason the reserve unit automatically lights the other beams. There is also a flashing light that indicates if the tail light burns out or is otherwise malfunctioning.
Another panel light indicates the proper operation of the stop lamp. Whenever the front or rear brake is applied this bulb indicates that the brake light circuit is completed. The only other bike that offers advanced safety warming devices is the Honda. Instead of flashing lights the Honda uses an arrow and dot, one painted on the rear brake panel and the other on the brake arm. When these two markers approach each other it is necessary to replace the brake lining.
The Yamaha features the type of handlebar switches that we would like to see on every bike.
One are that the Yamaha obviously gives a good deal of attention is the fit and finish on their motorcycles. All covers are well polished and the paint and chrome work are smooth and of high quality. Another nice touch is the use of Allen head bolts to secure the engine components. We feel that this is a much better approach for fastening the cases to the crankcase than the screws used by other Japanese manufacturers.
The TX weighed in at 515 pounds with a full tank of gas. Only the Kawasaki and Suzuki were heavier. It is unfortunate that a good portion of this weight feels placed relatively high in the frame.
Admittedly the TX is one of the finer vertical twins available today. But the multis are upon us now, and the smoothness they offer is hard to beat when considering long hours in the saddle. However, for some riders there is something about being aboard a vertical twin that seems well worth the price of some vibration. We would deem Yamaha's attempt to "update" the twin a success and at $1,563 the price can't be beat.
A Comparative Evaluation of the Top Touring Bikes
BMW R/75 /Honda CB 750 / Kawasaki Z1 / Suzuki GT 750 / Triumph T150V / Yamaha TX750
YAMAHA TX750
Several years ago the largest bike Yamaha offered for sale was the 350cc two-stroke twin. Their entire line was comprised solely of two-stroke machinery. Of course being interested in selling motorcycles Yamaha decided to enter the market with an overhead cam 650 twin four-stroke for the "touring" rider. However, in our estimation, the 650 leaves a lot to be desired as a touring or performance bike. In some aspects the XS1 was better than some other 650's kicking around at that time. However, it was not without its drawbacks, such as poor handling, excessive vibration, and poor braking. The updated XS2 was fitted with a disc brake, which improved the stopping ability considerably, however it was still plagued with handling problems.
When we had the opportunity of doing the first test on the 750 Yamaha last year we did not rule out the possibility it might only be a bored out, updated version of their 650. It wasn't though, and we were pleasantly surprised. Yamaha started with a clean piece of paper for the TX750 and designed a machine that was completely new from the front to the rear.
The TX750 is the only Japanese bike we know of that offers the buyer aluminum rims both front and rear. The disc brake (from last year's 650) has been redesigned and its both smooth and powerful. After many hard stops the brake didn't exhibit any tendencies to fade.
The hydraulic leverage Yamaha has built into their disc brake is considerable. It is necessary to touch the lever with only one finger to initiate noticeable braking response. At the higher speeds this type of leverage is a welcomed asset. However, at the slower speeds, if one isn't extremely careful, it is possible to lock the wheel with hardly any effort at all.
Because of efficiency of the front brake and the average performance of the rear we were able to get the TX stopped in third position in both panic stop braking tests. In one instant during the 35 to 0 test we had the front wheel lock solidly, and start to turn under. However, quick reflexes and a relatively stable motorcycle saved the situation and let the rider remain in the saddle.
It was quite evident that there is a great amount of weight transfer during any kind of stopping activity. This was obviously due to the exceptionally soft suspension that is fitted to the TX. Both the front suspension and the five-way adjustable shocks offer an extremely comfortable ride. This type of suspension was adequate only if we ran in a straight line at speeds of 75mph and less. Unfortunately if you gas it up now and then you will immediately notice that the comfort asset of the suspension immediately becomes a handling shortcoming. At speeds of 75 mph the machine acted as though it were riding over miniature rain grooves. We do feel that this behavior is a design fault of the machine that can and should be corrected for better handling.
We were disappointed with the cornering of the TX. When rounding a relatively fast corner (70 to 75 mph) that requires more lean angle than the average freeway corner the bike begins to twist and wobble. We put the blame on the soft suspension. Also there seems to be a bit more weight sitting up high than we consider prudent. This adds to the tendency to wiggle. Anyone who has experienced this on the XS2 will be relieved to know that the TX is no where near as violent.
Unfortunately to many designers seem to exhibit tendencies of favoring one extreme or another rather than striking a suitable compromise. We would like to see suspension components that fall somewhere between the ultra-stiff Kawasaki Z1 and the extra-soft TX750.
In evaluating the TX's performance around a slow corner it is necessary to consider the torque characteristics of the engine as well as the suspension. The throttle response on the TX proved to be the best of the six bikes we tested. However, this good response actually seems to hinder cornering at low speeds. Because of it the bike seems to right itself a bit. However, we were able to adjust to this behavior.
The TX, as well as some other Yamaha models, comes fitted with a hydraulic steering damper. It is interesting to note that during a test with a 350 Yamaha we removed this hydraulic damper and didn't notice any adverse affects at higher speeds. It was quite stable actually and we definitely did notice an improvement in low speed handling.
In an effort to reduce vibration Yamaha has installed a pair of contra-rotating weights at the bottom of the powerplant. These weights are chain driven so it is conceivable that their timing could be changed to dampen vibration at any spot in the power ranges. While the vibration on the TX wasn't great enough to cause a considerable amount of fatigue it did at times cause our fingertips to go numb. But even so it is perhaps the smoothest vertical twin that we have ever tested.
The single overhead cam engine itself offers nothing unique. Its layout is rather conventional. The engine is redlined at 7000 rpm. We found that figure to be the optimum shifting point for maximum performance. The TX features a five-speed gearbox.
The clutch is a conventional wet multi-plate design. The clutch operation was exceptionally smooth. Only the Honda required a lighter pull on the clutch lever. Engagement occurred slightly past the mid-point of travel.
On the first TX we tested last year we had some problems finding neutral at a stop. The unit we tested this time exhibited the same trait. We found it best to select neutral before coming to a stop.
Yamaha's positioning of the rider contact points is satisfactory. The handgrips which bow out in the middle and get slimmer at both ends, are better than most. The seat seemed just a little too narrow, but the firmness seemed right for putting on miles. As we mentioned the TX is plagued with some vibration. The footpegs transmit this vibration to the rider.
Yamaha has incorporated a few new features on the TX, as well as some other road models, that would possibly bewilder a Sopwith Camel pilot but do offer information to the rider. There is a small switch located on the rear brake backing plate that is opened if and when the brake lining wears past the safety point. This activates a warning light on a very impressive instrument panel. The rider then has two choices as far as deactivating the warning light. He can replace the brake shoes or he can be stubborn and cut the wiring.
We really liked the rather unique reserve lighting system, in the event that either the high beam or low beam circuit is broken for any reason the reserve unit automatically lights the other beams. There is also a flashing light that indicates if the tail light burns out or is otherwise malfunctioning.
Another panel light indicates the proper operation of the stop lamp. Whenever the front or rear brake is applied this bulb indicates that the brake light circuit is completed. The only other bike that offers advanced safety warming devices is the Honda. Instead of flashing lights the Honda uses an arrow and dot, one painted on the rear brake panel and the other on the brake arm. When these two markers approach each other it is necessary to replace the brake lining.
The Yamaha features the type of handlebar switches that we would like to see on every bike.
One are that the Yamaha obviously gives a good deal of attention is the fit and finish on their motorcycles. All covers are well polished and the paint and chrome work are smooth and of high quality. Another nice touch is the use of Allen head bolts to secure the engine components. We feel that this is a much better approach for fastening the cases to the crankcase than the screws used by other Japanese manufacturers.
The TX weighed in at 515 pounds with a full tank of gas. Only the Kawasaki and Suzuki were heavier. It is unfortunate that a good portion of this weight feels placed relatively high in the frame.
Admittedly the TX is one of the finer vertical twins available today. But the multis are upon us now, and the smoothness they offer is hard to beat when considering long hours in the saddle. However, for some riders there is something about being aboard a vertical twin that seems well worth the price of some vibration. We would deem Yamaha's attempt to "update" the twin a success and at $1,563 the price can't be beat.
