Post by Pardee on Jun 25, 2014 13:08:22 GMT -5
RAINTESTING THE YAMAHA 750
More and less than the Ultimate Triumph
Big Bike, June 1973
Motorcycling, somebody said, is a very private love affair.
So it was with the new Yamaha TX-750--just me and the bike.
And 14,734,828 baseball-size raindrops.
As I headed out the door, my $12.98 portable radio was cheerily chanting some top-40 piece of nonsense about how "It Never Rains in Southern California."
I turned around, went back, stepped on the radio, pulled my jacket over my head, and splashed out to the garage.
The new Yamaha sat in the middle of littered bits and pieces of a '66 Triumph that was slowly getting chopped and rebuilt, in the fond belief that it was possible to have a Trumpet free from the weaknesses and frailties Birmingham laid on an unsuspecting world. After eight years I figured I had all the frailties down pat--and knew how to correct them.
So does Yamaha--their 750, like the 650 before it, is not just a Better Machine--it's a Better Triumph. Possibly the Ultimate Triumph.
Their idea--overhead cam, electric starting, front disc brake, 750 engine, counterweight engine balancer, Mikuni carbs, Japanese electrics.
My idea--Q cams, Routt's 800 kit, Mikuni carbs, 60-percent dynamic balancing, Honda 160 coil, Sebring Power Converter and lots of Dow Silicone Seal.
Slight difference--Yamaha's Better Idea was Together and Running. Mine wasn't.
Wheeled the 750 around the pieces of English steel and out into the alley.
Choke/starter/start. Puffing water off my mustache like an asthmatic walrus, I clambered on board. And off and away, thinking damp macho thoughts.
Braked at the end of the street--hit the disc a little too hard. Before I got off the lever, the front end skidded slightly sideways.
Motorboated on down the road. Below three grand, the patented Omni-phase Balancing wasn't too impressive. The Yamaha vibrated pretty much like a stock Triumph. The Omni-phase is driven off the crankshaft, rotating two balance weights. One moves to offset crank vibration, and the second weight, according to Yamaha, cuts down on the secondary vibration.
On the freeway, staying away from grim semis and panicking old ladies, trying to avoid spray patterns sheeting up behind cars, I was a little busy to analyze if the balancer was any good above three thousand.
After a bit things settled down, and it got easier to play critic. The balancer does work, smoothing out most of the judder at cruising rpm. What remains is a comfortable reminder that there is a fairly large vertical twin driving along underneath you.
That unit left me with mixed feelings. It works--but at a certain cost. The first problem is that there is a certain power loss -- anytime you drive something in the opposite direction of a crank, some of the power of that crank will be reduced. The other price is that the Yamaha 750 is an extremely complex engine. The balancer is chain driven, as are the cam and the electric starter. This necessitates use of a high-pressure oiling system.
Regardless of how well things work, that still makes the Yamaha an engine that the average wrench isn't going to rebuild in his kitchen during a winter week. A local Yamaha dealership estimated that for a complete engine teardown/rebuild, there would be at least eight mechanic hours involved.
Of course, if you're a skilled wrench, or normally let an agency work on your scooter, there's no problem. You never get anything for free.
The next few soaked miles were spent getting wet to the skin; feeling the rain soak my eyebrows and run down under my shades; and stirring the gears around 20 hill-hauling tractor/trailers.
No question--the Yamaha's gearbox is an absolute 100-percent Better Idea. But there is a great deal more to rave about besides the fact that Yamaha builds an absolutely unbreakable gearbox. The gear ratios aren't just good--they're absolutely perfect.
Unlike the lamentable Triumph five-speed, the 750's gears are quite widely spaced. Wind through a gear, and shift. You don't hit in the middle of the powerband (points loss for cafe racers), but right at the bottom of that nice, big, gradual wave of horses.
The box feels like it has about the same ratios as the Triumph four-speed. Plus that fifth gear, an overdrive to keep you from having to hold high cruising revs. Yamaha's better ideal moved ahead of mine.
At least it did until I started running on freeway rain grooves.
The bike danced, jumped, wobbled and bounced. While all Japanese tires show a remarkable response to grooving, on the Yamaha 750 the response became a feverish excitement. I made a mental note that, if I owned the bike, a set of Dunlops or Avons would be the first change--even before yanking off the truck-styled fender.
There really isn't much to say about riding a freeway in driving rain. It's almost as boring as standing for a couple of hours in a needle shower, with a danger factor equivalent to being an arthritic matador standing in front of a charging Miura bull. That simile would have been creative as hell if it hadn't come to mind ducking some lane-changing fool in a Lamborghini.
The freeway swung inland and I cut off. Geared down the offramp and hit the brakes.
Now according to everything I've been told, one advantage of a disc brake is its imperviousness to water, oil, or anything else on the disc. One application, in theory, is enough to scrub the gork off the disc, and then the brake should work.
In theory. I gently applied two fingers to the disc. Nothing. The whole hand. Still nothing. Bashing down on the rear drum (nice and watertight and worked fine), I laid a full squeeze on the brake handle. The brake moaned like a stomped tomcat and drifted me down.
The next light, I tried again. Same thing. Dry, the disc works fairly well--almost as much stoping power as the old Triumph drum. In the wet, though, it has all the stopping power of a flattracker.
I lurched into a gas station, filled up and wiped my nose. wet or not, starting the 750 was always the same--touch the button and give it some gas.
The rain let up for a bit as I ran alongside the ocean. The gray water was dotted with sullen surfers, hard-assing in the hopes of some serious storm surf.
From there, it was up into the hills of Palos Verdes and more rain.
PV is a rich, hilly suburb. It also has one of the best (illegal) road racing courses in Southern California. A lot has been written about Mulholland, and the canyons, and the squirrels that play Le Mans around them. Nothing gets said about PV--which keeps profilers and police officers away from the roads of Palos Verdes.
It was too wet to be doing much leaning. Neither the Yamaha nor I was very enthusiastic about Paul Smarting around corners.
Especially with that still-sopping front brake.
Even as gingerly as I was riding, the Yamaha's feel sure wasn't the Ultimate Triumph--or even close to being like a Triumph. Reluctantly, the bike would lean through turns, and slowly return.
Going down the other side, a Porsche hissed past me. That did it. Even as wet as it was, I logically figured I should be able to blow the German car off.
The bike didn't agree. I gingerly bent through a turn, after the 912, and the back tire slid sideways. Got things picked up in a hurry, and tried again. Same thing. That made another thing the stock tires weren't--freeway cruisers and rain units.
I suddenly headed for home and dry clothes.
Without a falter, hesitation, or burble, the 750 ran right along, just as happy under an inch of water as it would be in the dry. Points from someone who's every now and then stood beside a drowned-out Triumph.
A few days later, there was a chance to bend through one of the canyons in the dry. Once again, the bike started, ran and shifted perfectly. But, once again, the handling could best be described as squirmy. On the freeway, the handling didn't allow much relaxing--there was too much of a reluctance about the bike.
So is the Yamaha TX-750 a Better Triumph? For the mechanicals (brakes excepted), absolutely. The 750 may be, as Yamaha feels, the ultimate development of a vertical twin.
As a bike for those who don't want the multi-cylinder blast of a Honda or Kawasaki, nor the simple churn of a Harley, the Yamaha 750 is the answer. Suspension and rubber modifications would vastly improve the handling.
So it's more than just a Better Triumph--it may be the ultimate medium-performance, -handling and -priced bike for the medium-haul touring biker.
But it isn't the Ultimate Triumph. That's still sitting in parts in my garage. That "private affair" just didn't happen.
More and less than the Ultimate Triumph
Big Bike, June 1973
Motorcycling, somebody said, is a very private love affair.
So it was with the new Yamaha TX-750--just me and the bike.
And 14,734,828 baseball-size raindrops.
As I headed out the door, my $12.98 portable radio was cheerily chanting some top-40 piece of nonsense about how "It Never Rains in Southern California."
I turned around, went back, stepped on the radio, pulled my jacket over my head, and splashed out to the garage.
The new Yamaha sat in the middle of littered bits and pieces of a '66 Triumph that was slowly getting chopped and rebuilt, in the fond belief that it was possible to have a Trumpet free from the weaknesses and frailties Birmingham laid on an unsuspecting world. After eight years I figured I had all the frailties down pat--and knew how to correct them.
So does Yamaha--their 750, like the 650 before it, is not just a Better Machine--it's a Better Triumph. Possibly the Ultimate Triumph.
Their idea--overhead cam, electric starting, front disc brake, 750 engine, counterweight engine balancer, Mikuni carbs, Japanese electrics.
My idea--Q cams, Routt's 800 kit, Mikuni carbs, 60-percent dynamic balancing, Honda 160 coil, Sebring Power Converter and lots of Dow Silicone Seal.
Slight difference--Yamaha's Better Idea was Together and Running. Mine wasn't.
Wheeled the 750 around the pieces of English steel and out into the alley.
Choke/starter/start. Puffing water off my mustache like an asthmatic walrus, I clambered on board. And off and away, thinking damp macho thoughts.
Braked at the end of the street--hit the disc a little too hard. Before I got off the lever, the front end skidded slightly sideways.
Motorboated on down the road. Below three grand, the patented Omni-phase Balancing wasn't too impressive. The Yamaha vibrated pretty much like a stock Triumph. The Omni-phase is driven off the crankshaft, rotating two balance weights. One moves to offset crank vibration, and the second weight, according to Yamaha, cuts down on the secondary vibration.
On the freeway, staying away from grim semis and panicking old ladies, trying to avoid spray patterns sheeting up behind cars, I was a little busy to analyze if the balancer was any good above three thousand.
After a bit things settled down, and it got easier to play critic. The balancer does work, smoothing out most of the judder at cruising rpm. What remains is a comfortable reminder that there is a fairly large vertical twin driving along underneath you.
That unit left me with mixed feelings. It works--but at a certain cost. The first problem is that there is a certain power loss -- anytime you drive something in the opposite direction of a crank, some of the power of that crank will be reduced. The other price is that the Yamaha 750 is an extremely complex engine. The balancer is chain driven, as are the cam and the electric starter. This necessitates use of a high-pressure oiling system.
Regardless of how well things work, that still makes the Yamaha an engine that the average wrench isn't going to rebuild in his kitchen during a winter week. A local Yamaha dealership estimated that for a complete engine teardown/rebuild, there would be at least eight mechanic hours involved.
Of course, if you're a skilled wrench, or normally let an agency work on your scooter, there's no problem. You never get anything for free.
The next few soaked miles were spent getting wet to the skin; feeling the rain soak my eyebrows and run down under my shades; and stirring the gears around 20 hill-hauling tractor/trailers.
No question--the Yamaha's gearbox is an absolute 100-percent Better Idea. But there is a great deal more to rave about besides the fact that Yamaha builds an absolutely unbreakable gearbox. The gear ratios aren't just good--they're absolutely perfect.
Unlike the lamentable Triumph five-speed, the 750's gears are quite widely spaced. Wind through a gear, and shift. You don't hit in the middle of the powerband (points loss for cafe racers), but right at the bottom of that nice, big, gradual wave of horses.
The box feels like it has about the same ratios as the Triumph four-speed. Plus that fifth gear, an overdrive to keep you from having to hold high cruising revs. Yamaha's better ideal moved ahead of mine.
At least it did until I started running on freeway rain grooves.
The bike danced, jumped, wobbled and bounced. While all Japanese tires show a remarkable response to grooving, on the Yamaha 750 the response became a feverish excitement. I made a mental note that, if I owned the bike, a set of Dunlops or Avons would be the first change--even before yanking off the truck-styled fender.
There really isn't much to say about riding a freeway in driving rain. It's almost as boring as standing for a couple of hours in a needle shower, with a danger factor equivalent to being an arthritic matador standing in front of a charging Miura bull. That simile would have been creative as hell if it hadn't come to mind ducking some lane-changing fool in a Lamborghini.
The freeway swung inland and I cut off. Geared down the offramp and hit the brakes.
Now according to everything I've been told, one advantage of a disc brake is its imperviousness to water, oil, or anything else on the disc. One application, in theory, is enough to scrub the gork off the disc, and then the brake should work.
In theory. I gently applied two fingers to the disc. Nothing. The whole hand. Still nothing. Bashing down on the rear drum (nice and watertight and worked fine), I laid a full squeeze on the brake handle. The brake moaned like a stomped tomcat and drifted me down.
The next light, I tried again. Same thing. Dry, the disc works fairly well--almost as much stoping power as the old Triumph drum. In the wet, though, it has all the stopping power of a flattracker.
I lurched into a gas station, filled up and wiped my nose. wet or not, starting the 750 was always the same--touch the button and give it some gas.
The rain let up for a bit as I ran alongside the ocean. The gray water was dotted with sullen surfers, hard-assing in the hopes of some serious storm surf.
From there, it was up into the hills of Palos Verdes and more rain.
PV is a rich, hilly suburb. It also has one of the best (illegal) road racing courses in Southern California. A lot has been written about Mulholland, and the canyons, and the squirrels that play Le Mans around them. Nothing gets said about PV--which keeps profilers and police officers away from the roads of Palos Verdes.
It was too wet to be doing much leaning. Neither the Yamaha nor I was very enthusiastic about Paul Smarting around corners.
Especially with that still-sopping front brake.
Even as gingerly as I was riding, the Yamaha's feel sure wasn't the Ultimate Triumph--or even close to being like a Triumph. Reluctantly, the bike would lean through turns, and slowly return.
Going down the other side, a Porsche hissed past me. That did it. Even as wet as it was, I logically figured I should be able to blow the German car off.
The bike didn't agree. I gingerly bent through a turn, after the 912, and the back tire slid sideways. Got things picked up in a hurry, and tried again. Same thing. That made another thing the stock tires weren't--freeway cruisers and rain units.
I suddenly headed for home and dry clothes.
Without a falter, hesitation, or burble, the 750 ran right along, just as happy under an inch of water as it would be in the dry. Points from someone who's every now and then stood beside a drowned-out Triumph.
A few days later, there was a chance to bend through one of the canyons in the dry. Once again, the bike started, ran and shifted perfectly. But, once again, the handling could best be described as squirmy. On the freeway, the handling didn't allow much relaxing--there was too much of a reluctance about the bike.
So is the Yamaha TX-750 a Better Triumph? For the mechanicals (brakes excepted), absolutely. The 750 may be, as Yamaha feels, the ultimate development of a vertical twin.
As a bike for those who don't want the multi-cylinder blast of a Honda or Kawasaki, nor the simple churn of a Harley, the Yamaha 750 is the answer. Suspension and rubber modifications would vastly improve the handling.
So it's more than just a Better Triumph--it may be the ultimate medium-performance, -handling and -priced bike for the medium-haul touring biker.
But it isn't the Ultimate Triumph. That's still sitting in parts in my garage. That "private affair" just didn't happen.