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{{DISPLAYTITLE:{{PAGENAME}}: history, specs, pictures}} | {{DISPLAYTITLE:{{PAGENAME}}: history, specs, pictures}} | ||
{{Motorcycle | |||
|name = Yamaha FZR750 | |||
{{ | |photo = Yamaha-FZR750-87--3.jpg | ||
|name = | |aka = FZR750R Genesis | ||
| | |||
|aka = | |||
|manufacturer = [[Yamaha]] | |manufacturer = [[Yamaha]] | ||
|parent_company = | |parent_company = | ||
|production = | |production = 1987 | ||
|model_year = | |model_year = | ||
|predecessor = | |predecessor = | ||
|successor = | |successor = | ||
|class = | |class = | ||
|engine = | |engine = Four stroke, transverse four cylinder, DOHC, 5 valves per cylinder. | ||
|bore_stroke = | |bore_stroke = | ||
|compression = | |compression = 11.2:1 | ||
|top_speed = 145 mph (234 km/h) | |top_speed = 145 mph (234 km/h) | ||
|power = 118.41 HP (88.3 KW) @ 12000RPM | |power = 118.41 HP (88.3 KW) @ 12000RPM | ||
|torque = | |torque = | ||
|fuel_system = | |fuel_system = | ||
|ignition = | |ignition = Electronic triggered | ||
|spark_plug = | |spark_plug = {{sparkplug|NGK DR8ES-L}} | ||
|battery = | |battery = | ||
|transmission = | |transmission = 6 Speed | ||
|frame = Aluminum, twin spar | |||
|suspension =Front: 41mm Kayaba forks 130mm [[wheel]] travel adjustable for spring preload and rebound damping, <br> | |||
Rear: Monoshock single Kayaba [[damper]] 30mm wheel travel adjustable for spring preload and rebound damping, | |||
|brakes =Front: 2x 320mm disc 2 [[piston]] [[caliper]] <br>Rear: Single 267mm disc 2 piston caliper | |||
|brakes =Front: | |||
|front_tire = {{tire|130/70-17}} | |front_tire = {{tire|130/70-17}} | ||
|rear_tire = {{tire|180/55-17}} | |rear_tire = {{tire|180/55-17}} | ||
Line 37: | Line 34: | ||
|height = | |height = | ||
|seat_height = | |seat_height = | ||
|dry_weight = | |dry_weight = 213 kg / 469.5 lbs | ||
|wet_weight = | |wet_weight = 235 kg / 496 lbs | ||
|fuel_capacity = 5.28 Gallon (20.00 Liters) | |fuel_capacity = 5.28 Gallon (20.00 Liters) | ||
|oil_capacity = | |oil_capacity = | ||
|oil_filter = K&N KN-401 | |||
|fuel_consumption = | |fuel_consumption = | ||
|turning_radius = | |turning_radius = | ||
|related = | |related = | ||
|competition = | |competition = [[Suzuki GSX-R750]] | ||
}} | }} | ||
The '''[[Yamaha]] FZR750R''' was a in-line four, [[four-stroke]] standard produced by [[Yamaha]] between 1988 and 1992. It could reach a top speed of 145 mph (234 km/h). Claimed [[horsepower]] was 118.41 HP (88.3 KW) @ 12000 RPM. | The '''[[Yamaha]] FZR750R''' was a in-line four, [[four-stroke]] standard produced by [[Yamaha]] between 1988 and 1992. It could reach a top speed of 145 mph (234 km/h). Claimed [[horsepower]] was 118.41 HP (88.3 KW) @ 12000 RPM. | ||
==Engine== | ==Engine== | ||
The engine was a [[liquid cooled]] in-line four, four-stroke. A 72.0mm [[bore]] x 46.0mm [[stroke]] result in a [[displacement]] of just 749.0 cubic centimeters. Fuel was supplied via a double overhead cams/twin [[cam]] (dohc). | The engine was a [[liquid cooled]] in-line four, four-stroke. A 72.0mm [[bore]] x 46.0mm [[stroke]] result in a [[displacement]] of just 749.0 cubic centimeters. Fuel was supplied via a double overhead cams/twin [[cam]] (dohc). The engine featured a 11.2:1 [[compression ratio]]. | ||
==Drive== | ==Drive== | ||
The bike has a 6-speed transmission. | The bike has a 6-speed transmission. | ||
==Chassis== | ==Chassis== | ||
It came with a | It came with a 120/70 VR17 front [[tire]] and a 160/60 VR18 rear tire. Stopping was achieved via 2x 320mm disc 2 piston caliper in the front and a Single 267mm disc 2 piston caliper in the rear. The front suspension was a 41mm Kayaba forks 130mm wheel travel adjustable for spring preload and rebound damping, while the rear was equipped with a Monoshock single Kayaba damper 30mm wheel travel adjustable for spring preload and rebound damping,. The FZR750 Genesis was fitted with a 20 Liters / 5.2 gal fuel tank. The bike weighed just 213 kg / 469.5 lbs. | ||
== Photos == | |||
[[File:Yamaha-FZR750-87--3.jpg|600px|Yamaha FZR750]] | |||
[[File:Yamaha-FZR-750R-Genesis-87.jpg|600px|Yamaha FZR750]] | |||
[[File:Yamaha-FZR750-87--4.jpg|600px|Yamaha FZR750]] | |||
[[File:Yamaha-FZR750-87.jpg|600px|Yamaha FZR750]] | |||
== Review == | |||
Source Cycle Magazine of 1987 | |||
With the introduction of the 1987 models, though, particularly the new FZR | |||
Yamahas, we're beginning to see two elemental yet heretofore disparate | |||
motorcycling structureschassis and enginescome together in a technical | |||
harmony and balance the sport hasn't seen since the Norton featherbed. | |||
Not that Yamaha has a corner on the technological market by any means. | |||
Honda with its CBR fours, however, appears to be exploring the aerodynamic | |||
route to speed while the bikes make do with steel perimeter chassis. | |||
Suzuki's and Kawasaki's aluminum street chassis don't yet reflect the | |||
current spar-design thinking which is winning on the Grand Prix circuit, and | |||
while the oil-cooled Suzuki engines push the light bikes to respectable | |||
speeds, the engines themselves aren't powerhouses. No, out of the few 1987 | |||
models the Japanese let the press peek at, our vote for the most homogenized | |||
mixture of current-think parts goes to Yamaha. A collection of high-tech | |||
bits does not guarantee a great bike, yet this assemblage seems to represent | |||
the future, now. What are we looking at? | |||
Clearly, two performance innovations combined: Yamaha's use of a | |||
five-valve-per-cylinder head on the FZR bikes, set for the first time in the | |||
company's race-bred Deltabox aluminum chassis. Because the sum of these | |||
innovations has such import, it's helpful to evaluate the parts separately, | |||
winnowing the misconceptions from the truth. First, the cylinder head | |||
Yamaha developed its novel five-valve technology for specific | |||
gains. First on the list was a compact, nearly flat combustion | |||
chamber of minimum surface area. In a two-valve design, adequate | |||
valve area comes only by tilting the valves away from each other | |||
and making the head somewhat hemispherical, but with five valves | |||
the poppets can set into an almost flat | |||
chamber. The Yamaha's head is only slightly domed, its piston slightly | |||
concave. The resulting lens-shaped chamber concentrates the charge tightly | |||
around the central spark plug, and this means most of the charge is quickly | |||
inflamed shortly after the spark. The resulting short total combustion time | |||
cuts energy loss through heat to the cooler metal of the piston and head, | |||
and that saved energy is applied to the job of pushing the pistons down. | |||
Being nearly flat, both piston and head offer minimum surface area, and | |||
this further cuts combustion heat loss, again translated into power gains. | |||
Detonationengine knocksets the upper limit on compression ratio, but the | |||
five-valve's rapid combustion can consume the charge before detonation has | |||
time to occur, permitting an unusually high compression ratio of 11.2:1 | |||
(Honda's VFR750 is good for 10.5:1, Suzuki's GSX-R750 10.6:1). This not only | |||
gives the Yamaha 750 and 1000 more punch across the powerband, it also | |||
increases fuel economy. | |||
The paired exhausts and trebled intakes bring more advantages. To explain | |||
one, we'll use a two-stroke analogy. Imagine two cylinder-wall ports, one | |||
wide and short, another narrow and tall. Both 'have the same area when fully | |||
open. Clearly, as the piston falls, the wide port will expose flow area | |||
fasterbecause the narrow port is taller, it will take longer to open fully. | |||
Yet when both are fully open, they have identical area. | |||
Now for the four-stroke equivalent. Imagine two engines, one built with a | |||
single, large intake valve, the other with three much smaller intakes of | |||
identical total head area to that of the large one. Imagine that we equip | |||
these engines with cams that accelerate the valves at identical rates. Which | |||
design will expose flow area more quickly? In analogy with the two-stroke | |||
case, our flow area will be the "width" of the port multiplied by the | |||
distance it is opened. For the four-stroke, the width equates to the | |||
perimeter of the intake valve or valves. The height is the valve liftthe | |||
same for both engines because the valves are opening at the same rate. | |||
Consider specific cases; the distance around a single 37mm intake valve is | |||
pi times 37, or about 116mm. Three valves of the same total head area would | |||
be 21.4mm diameter each, and the distance around all three will be pi times | |||
three, times 21.4, or 202mm. Our three-intake-valve design exposes flow area | |||
1.74 times faster (202 ± 116) than a single-valve design. Work the figures | |||
for the twin intakes of a four-valve setup and you find the five-valve | |||
Yamaha concept has a 22 percent advantage in rate of area exposure. | |||
Here's a third benefit: Rapid opening gets the valve(s) out of the way of | |||
the flow quickly, keeping the loss-producing restriction between valve and | |||
seat to a minimum. Unfortunately, getting the valve open fast means serious | |||
acceleration levelsup to 3000 times the force of gravity in some racing | |||
engines. High valve opening and closing rates bring problemslike seat | |||
hammering, cam and tappet scuffing, seat recession or loosening, or outright | |||
valve breakage. The standard ways of limiting valve acceleration are to | |||
reduce the lift and/or extend duration. Both have drawbacks: cutting the | |||
lift cuts the flow, and extending the duration invites reverse flow from the | |||
cylinder to the intake pipe; either cuts power. | |||
The Manx Norton road racer had a radical 340-degree intake duration, | |||
thought by many to be its key to high performance, but much of that | |||
impressive timing existed because the designer couldn't get those big, heavy | |||
valves up off their seats in anything less without breaking them. The Manx | |||
could actually have made more power, and over a wider range, had it been | |||
able to run less intake timing. These compromises were cut perilously close | |||
in many cases; the great 1960s MV road racers would toss their valves if | |||
overrevved by only 300 rpm! | |||
Ideally, as the piston nears the bottom of its intake stroke at high | |||
revs, the fuel/air charge is rushing towards the valve at something over 300 | |||
feet per second, and this velocity doesn't disappear just because the piston | |||
stops at BDC and reverses direction. It's desirable to keep the intake(s) | |||
open past BDC long enough to let this fortune in intake kinetic energya | |||
kind of free superchargingspend itself against the rising piston, forcing | |||
in extra mixture to make extra power. At the instant that intake flow piles | |||
to a stop against the rising pressure in the cylinder, the intake(s) should | |||
snap shut, trapping these goodies. But as we have observed, valves and | |||
springs can only take so much acceleration, and hence two-valve designs | |||
suffer under a severe compromise between what is best for airflow and power | |||
and what is possible mechanically. Again, the answer is smaller valves and | |||
more of them. | |||
Scale a part down in dimensions and it loses weight faster than it loses | |||
strengthweight is proportional to roughly the cube of the linear dimension, | |||
while the strength is related to a lesser power. This means small valves can | |||
stand higher acceleration rates than can large ones. Consequently, not only | |||
do many small valves expose perimeter area faster than a single one of equal | |||
total area, but they can also be opened faster to redouble the effect. | |||
What Yamaha gets in return for its extra parts is an unusually wide and | |||
strong powerband. A two-valve or four-valve engine could be made to give as | |||
much peak power, or as much low-end and mid-range, but not both. The Yamaha | |||
makes its numbers with grace, not with extremes of materials or design. | |||
Next comes the matter of 'valve springs. From your place on a tall stool | |||
in an air-conditioned drafting room, logic tells you that two revolutions of | |||
the crank equals one valve-spring fatigue cycle. From the hot dyno cell or | |||
race track, the springs see things differently: at high crank speeds the | |||
rapid acceleration imparted by the cam lobe approximates a hammer blow. This | |||
can make the coils of valve springs "ring" or vibrate end-to-end. This | |||
ringing vibration may have a characteristic frequency of hundreds of cycles | |||
per second, so it can, if excited at high speed, add up fatigue cycles so | |||
fast that springs break prematurely. This spring surge can also cause | |||
irregular actions at the valvefloat, bounce, etc.that deteriorate other | |||
parts as well. | |||
Designers like "soft" rate springsthose with little difference between | |||
their seat pressure and their open pressure. Why? Too much spring pressure | |||
can overload the oil film between cam and tappet, leading to scuffing. | |||
Unfortunately, such springs also tend to have low natural frequencies. | |||
Standard texts on valve-gear design suggest the spring frequency should be | |||
at least eleven times the camshaft speed, but it is difficult to provide for | |||
a large single spring or spring pack sufficient to close a single large | |||
intake valve in a high-rpm engine. Such high-revvers need high-rate springs | |||
with very few coils, operating at extreme stress levels, manufactured with | |||
special processing and many inspections. Expensive, and difficult to make. | |||
On the other hand, three tiny valves eliminate most spring problems. Tiny | |||
springs are now all you need to handle the job, and such small springs | |||
provide high natural frequencies without high-tech manufacturing and | |||
expense. The single springs Yamaha uses are dualratethe coils wound with | |||
two pitches, a fine and a coarse. With the valve closed, all the coils are | |||
in action; as the spring compresses during valve lift, the fine-pitch | |||
section coil-binds, leaving only the coarse coils in action. This in effect | |||
gives the spring two natural frequencies instead of one: a lower frequency | |||
when the valve is closed, a higher one when it is open. This "confuses" | |||
spring surge by favoring first one and then the other frequency, and tending | |||
to suppress others in between. | |||
Using one large intake, the designer must save all the weight he possibly | |||
can by making the valve's stem skinny and short, and thinning down the head. | |||
Such compromise valves usually employ stems whose diameter is only 18 | |||
percent of the valve-head diameter. Such valves, while light, affect both | |||
durability and performance. They cramp the intake port into a hunched-over | |||
position, huddled close under the valve spring seat and making a sudden | |||
90-degree turn to enter the cylinder. This forces designers to use a short, | |||
unsupportive valve guide that soon wears out, leaks, and forces the valve to | |||
leak. Second, the sudden 90-degree turn flings most of the airflow to the | |||
outside of the bend, so it enters the cylinder through only half of the | |||
valve's circumference. These losses show up on a torque curve, making | |||
foothills out of what might have been mountains. | |||
Yamaha's three small intake valves can afford stem diameters a full 25 | |||
percent of their head diameter, and their length is more than four times | |||
their head diameterlike the best racing designs. This allows excellent, | |||
long-lasting support from an adequate valve guide that doesn't intrude into | |||
the port, and also provides room for a nearly straight downdraft intake of | |||
excellent airflow qualities. | |||
Yamaha chose to operate all these valves in racing fashion, using one cam | |||
lobe and inverted-bucket-type tappet per valve. Why not cut manufacturing | |||
costs and ease maintenance by incorporating some form of forked rocker arms, | |||
with clearance adjustment by screws and lock-nuts? What was gained in | |||
valve-acceleration tolerance by using small poppets could easily be thrown | |||
away by introducing a flexible element into the systema rocker arm loaded | |||
in bending. A rocker arm is effectively a high-rate spring, inserted between | |||
cam lobe and valve. When the lobe accelerates the tappet, the spring first | |||
winds up, and only then begins to lift the valve. When the cam contour calls | |||
for the valve to slow for peak lift and then reverse, the spring unwinds, | |||
then continues to oscillate for the rest of the valve event. If the | |||
rocker-arm "spring" is again unwinding as the valve approaches its seat, the | |||
valve may hit the seat with not only the seating velocity built into the cam | |||
contour but also with the extra velocity resulting from rocker-arm | |||
unwinding. If the rpm is up, and the designed-in seating velocity is already | |||
on the high side, the result will be seat hammering, recession, or | |||
loosening. With the rocker arm oscillating like this, it too can pile up | |||
fatigue cycles like a surging valve spring until it breaks as well. | |||
To go with their high-rpm, rockerless valve gear, Yamaha chose the most | |||
reliable method of valve clearance adjustmentselective-fit lash caps on the | |||
valve stem ends. Unlike clearance discs (shims) set into recesses on the | |||
tops of the bucket tappets, these cannot come adrift during valve float, | |||
free to wreck the top end. Adjusting clearance with this bulletproof system | |||
does require removing the cams, but Yamaha has used hardened cam lobes to | |||
extend the service interval. | |||
And what about gross flow? Do three valves flow more air than one or two? | |||
Years ago, Harry Weslake, the famous English airflow pioneer, believed he | |||
had proven one valve was bestit minimized wall-friction losses. True, but | |||
that small gain ignored the huge gains that would soon come from the use of | |||
multiple, long-stemmed valves and gently curved ports. It also ignored the | |||
greatly increased safe rev limit and durability of multi-valve designs; | |||
either of these advantages by itself is enough to make nonsense of any | |||
putative extra flow through a single valve. | |||
Is there any limit to the process of valve multiplication? Yamaha has | |||
tried as many as seven valvesfour intakes and three exhaustsin larger-bore | |||
engines. Five valves seem to work best in motorcycle sizes; more tend not to | |||
leave enough head material between seats and spark-plug holes. On the other | |||
hand, the old process of forming all the valve seats and the spark-plug | |||
threads as a single austentic iron insert set into the aluminum head might | |||
offer a way around even that limitation. | |||
The iron insert would have another advantage as well; small, big-bore | |||
engines have a lot of combustion chamber surface area in relation to volume, | |||
and that means rapid heat loss. Compared to aluminum, iron is an insulator | |||
that has proven its ability to keep the heat where it belongsin the | |||
combustion gases. | |||
So five-valve engines are the ticket inwe knew that last year, and they | |||
haven't changed much for 1987. Show us something new, you say? Right this | |||
way. While you've seen aluminum chassis on the street before, you've never | |||
seen one so close to the track as this one. Conventional motorcycle chassis | |||
have almost always been made from tubesbolted, brazed, or welded together. | |||
If any tubing is made smaller and of heavier wall thickness, so the weight | |||
per foot remains constant, the bending and torsional stiffness of the tubing | |||
drops, reaching the lowest limit as the tube becomes a solid bar. Reverse | |||
the process and the tube becomes stiffer roughly in proportion to the square | |||
of the tube diameter until at the other extreme the likelihood of the now | |||
very thin wall crumpling under load becomes greater than the possibility of | |||
actual rupture or tearing of the material. Designers seek- ing a high | |||
stiffness-to-weight ratio make their structures with the largest possible | |||
diameter and the thinnest possible wall. A single-tube chassis represents | |||
the conceptual ultimate in bending and torsional resistance; many | |||
experimental frames have been built this way. | |||
Ken Sprayson, a noted English frame specialist, built steel single-beam | |||
chassis in the 1950s. In 1969 the Spanish OSSA firm fielded a welded-sheet | |||
aluminum 250 road-racing chassis. Harry Hunt constructed one of riveted | |||
aluminum sheet two years later. The erratic innovator Eric Offenstadt ran a | |||
welded aluminum monocoque 750 at Daytona in 1972. These experiments | |||
apparently showed only that aluminum could not long survive the vibration of | |||
motorcycle service. We now know correct design procedures can produce | |||
aluminum structures of any desired lifetime, even in a motorcycle chassis, | |||
but there is a compromise between weight and life. | |||
High-frequency engine vibration is deadly to thin aluminum, yet in 1979 | |||
Yamaha pioneered conventional multi-tube designs in a welded-aluminum | |||
chassis with wall thicknesses of two to three millimeters. The light metal | |||
allowed both the wall thickness and diameter to increase with no weight | |||
penalty. Soon they were both stiffer and lighter than steel designs, and | |||
durable enough to last more than one race. | |||
How do you stiffen an existing twin-loop frame? The goals are clear: the | |||
steering head shouldn't flex and should resist braking forces, the frame | |||
must be stiff enough torsionally to prevent the wheels from straying from | |||
their common plane, and untriangulated bays should be braced with diagonals. | |||
The best way to do this is to deepen the top frame rails to better resist | |||
bending and torsion, and to provide equally deep cross-members to make the | |||
two work together. Make the load path direct between steering head and rear | |||
fork pivot. Do this and watch the top frame rails grow and the lower loops | |||
shrink into mere engine-hangers. The opening between the top rails remains | |||
to provide clearance for engine upper structure, or for service access. | |||
The 1982 racing season was a turning point for Yamaha. The company had | |||
mastered the multi-tube aluminum chassis and began working towards something | |||
else in very much the way described above. That something else was the OW61, | |||
a motorcycle not in itself successful, but a necessary step towards the | |||
future. If you looked at that chassis with 1982 hindsight it was just a | |||
twin-loop design with its engine hanging from already-shrinking lower frame | |||
members. The engine, too, was significant, its two cylinder pairs set close | |||
to 90 degrees, a configuration that cancels major vibratory forces. The | |||
engine was supported in rubber mounts since the chassis designer had finally | |||
decided to make the chassis stiff enough to do its job unassisted and let | |||
the engine provide only power. The concept of a load-bearing engine is | |||
attractive, but such a system fatigues an aluminum frame's welds. | |||
The following year the upper rails grew again, the lower members | |||
shrinking correspondingly. Yamaha repeated the process each succeeding year: | |||
the current Yamaha YZR500 road racer's chassis is a delta-shaped twin | |||
boxbeam, made as deep as the steering head and as wide as it must be to | |||
clear the engine. It extends almost straight from head to swing-arm pivot, | |||
and is made largely from special weldable aluminum sheet about two | |||
millimeters thick. Almost without exception, previous designs have carried | |||
steering-head bearings in the ends of a piece of tubingthe steering head | |||
properand have joined the rest of the structure not to the bearing area, | |||
but to the head tube, relatively far from the bearings. This sacrifices | |||
strength by cantilevering the bearings out in space above and below the | |||
points at which chassis loads are fed in. Yamaha put top and bottom bearings | |||
into pieces of plate which extend rearward into the box structure, directly | |||
carrying head-bearing loads into the frame. A tube separates the bearing | |||
pair, but it is no longer loaded in bending. At the rear, plates at the side | |||
pick up the rear fork pivot pin and the footpeg carriers. Between the | |||
steering head and swing-arm pivot, the twin beams are gracefully shaped, | |||
cross-members blended into them in organic-looking fashion. | |||
Although the original OW61 used extruded frame tubes, Yamaha's present | |||
racing chassis are fabricated from machined shapes and from special-purpose | |||
pressings in sheet aluminum. Why do they last when frames before them | |||
cracked? Using the longest possible welds cuts down the load per inch of | |||
bead. In the Deltabox, the welds have the same dimensions as the frame | |||
itself, and because the frame is largely continuous pressings, there is a | |||
bare minimum of welds in the first place. The resulting structure probably | |||
has about five times the torsional and bending stiffness of previous | |||
multi-tube designs. | |||
In the new FZR Yamahas, we now have a Deltabox design for the street, | |||
significant because this signifies the Deltabox design has passed rigorous | |||
vibration, drop, and longevity testing. As in the competitors' aluminum | |||
chassis, Yamaha uses high-quality castings for the steering-head and | |||
swing-arm structures, a cost-cutting move. Castings have poor fatigue | |||
properties as compared with wrought materials (rolled or extruded mill | |||
forms) because traditionally most castings are full of voids or impurities, | |||
both of which invite crack growth under stress cycling. On the other hand, | |||
castings lend themselves to high-volume production where machining from | |||
solid stock does not. | |||
There is an answer, though. Traditional die-casting fills the die by | |||
gravity flow, and dissolved gases in the metal pass out of solution during | |||
solidification to form voids. Vacuum casting fills the die by drawing the | |||
metal up from below: as the liquid emerges into the mold, the low pressure | |||
there causes evolution of the gases in much the same manner as uncapping a | |||
bottle of soda. The result is a casting with greatly improved fatigue | |||
properties. Another approach is Hot Isostatic Pressing (HIP), which | |||
submerges castings in a hot, high-pressure (15,000 - 30,000 psi) bath, in | |||
effect forging the part from all directions, closing the voids, and | |||
therefore reducing the population of crack nucleation sites. The | |||
formed-aluminum sections of a Deltabox chassis, pressed in the same fashion | |||
as auto body parts, already lend themselves well to quantity production with | |||
no sacrifice in strength. | |||
Welding aluminum is tricky. Any welding process is really a continuous | |||
casting in which the molten weld puddle freezes behind the moving torch arc. | |||
Just as the freezing of sea water yields fresh-water ice and a slush of | |||
concentrated salt water, the freezing of the weld puddle has some tendency | |||
to produce a weld area of purified aluminum with a zone of concentrated | |||
impurities and alloying elements down its centerline. Aluminum expands far | |||
faster than steel; after welding its cooling contractions may tear the bead | |||
apart, particularly in that sensitive, impurity-rich centerline zone. Welds | |||
made with "high restraint"on parts jigged so firmly they cannot move easily | |||
during coolingare especially subject to cracking in this fashion. Taking | |||
care in the design not only of the chassis but of how its welds are | |||
sequenced can make the difference between cracking and not cracking. | |||
Yamaha uses robots to weld their aluminum frames, and began using robot | |||
welders in 1974. The trend in robotics in the U.S. is toward many-jointed | |||
arms that mimic human function; in Japan robots now tend to be specialized | |||
for particular jobs. Yamaha builds its own robots for about half the cost of | |||
commercially available machines, and in a typical operation, several | |||
machines work with one or more human "stagers." The stager picks up frame | |||
elements and locates them accurately into a fixture on .a rotary tablesuch | |||
fixturing is very difficult for robots, but easy for humans. The table | |||
indexes 180 degrees, carrying the fixtured part into the operating envelope | |||
of the robots. A glare curtain sweeps across, protecting the worker's eyes | |||
from the ultraviolet light as the welding begins, often performed by more | |||
than one robot simultaneously. The worker removes the just-completed part | |||
and fixtures another. He may also complete welds in areas difficult for the | |||
machines to reach. Why robots? Can you repeatedly place an arc source to | |||
within 0.004 inch anywhere in space, eight hours a day, Monday-morning | |||
hangover or no? | |||
What can Yamahaor any other manufacturer for that matterdo for an | |||
encore? The latest FZRs still look a step behind in the aerodynamic fight: | |||
maybe slicker bodywork for '88. Or how about a reliable, responsive | |||
fuel-injection system? And aluminum isn't the only stuff to make frames | |||
from: a carbon-fiber chassis? A ceramic cylinder block? When will center-hub | |||
steering come of two-wheeled age? | |||
Yamaha's five-valve engines and Deltabox chassis are but a momentary stay | |||
against the unending rush of technology, but together they represent a canny | |||
balance between performance and handling, between technology and rider | |||
ability. The featherbed Nortons did the same, and we remember and revere | |||
such machines even today. Will these new Yamahas be worthy of such | |||
immortality? We'll all soon know | |||
Source Cycle Magazine | |||
==Specifications== | |||
{| class="wikitable" | |||
|- | |||
!Make Model | |||
|Yamaha FZR750R Genesis | |||
|- | |||
!Year | |||
|1987 | |||
|- | |||
!Engine Type | |||
|Four stroke, transverse four cylinder, DOHC, 5 valves per cylinder. | |||
|- | |||
!Displacement | |||
|749 cc / 45.7 cu-in | |||
|- | |||
!Bore X Stroke | |||
|68 x 51.6 mm | |||
|- | |||
!Compression | |||
|11.2:1 | |||
|- | |||
!Cooling System | |||
|Liquid cooled | |||
|- | |||
!Induction | |||
|4x 34mm Mikuni carburator | |||
|- | |||
!Ignition | |||
|Electronic triggered | |||
|- | |||
!Spark Plug | |||
|NGK, DR8ES-L | |||
|- | |||
!Starting | |||
|Electric | |||
|- | |||
!Max Power | |||
|106 hp / 77.4 kW @ 10500 rpm | |||
|- | |||
!Max Power Rear Tire | |||
|92.5 hp @ 10500 rpm | |||
|- | |||
!Max Torque | |||
|7.2 kgf-m / 72 Nm @ 8250 rpm | |||
|- | |||
!Clutch | |||
|Wet, multiple discs, cable operated | |||
|- | |||
!Transmission | |||
|6 Speed | |||
|- | |||
!Final Drive | |||
|Chain | |||
|- | |||
!Frame | |||
|Aluminum, twin spar | |||
|- | |||
!Front Suspension | |||
|41mm Kayaba forks 130mm wheel travel adjustable for spring preload and rebound damping, | |||
|- | |||
!Rear Suspension | |||
|Monoshock single Kayaba damper 30mm wheel travel adjustable for spring preload and rebound damping, | |||
|- | |||
!Front Brakes | |||
|2x 320mm disc 2 piston caliper | |||
|- | |||
!Rear Brakes | |||
|Single 267mm disc 2 piston caliper | |||
|- | |||
!Front Tire | |||
|120/70 VR17 | |||
|- | |||
!Rear Tire | |||
|160/60 VR18 | |||
|- | |||
!Dry Weight | |||
|213 kg / 469.5 lbs | |||
|- | |||
!Wet Weight | |||
|235 kg / 496 lbs | |||
|- | |||
!Fuel Capacity | |||
|20 Liters / 5.2 gal | |||
|- | |||
!Consumption Average | |||
|18 km/lit | |||
|- | |||
!Braking 60 - 0 / 100 - 0 | |||
|13.5 m / 38.9 m | |||
|- | |||
!Standing ¼ Mile | |||
|11.2 sec / 195.6 km/h | |||
|- | |||
!Top Speed | |||
|240.2 km/h / 149.2 mph | |||
|} | |||
==In Media== | ==In Media== |