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{{Motorcycle | |||
|name = Racing Bikes Z750 | |||
|photo=Yamaha--TZ-750-01.jpg | |||
|aka = | |||
|manufacturer = | |||
|parent_company = | |||
|production = | |||
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|predecessor = | |||
|successor = | |||
|class = Racing | |||
|engine = | |||
|bore_stroke = | |||
|compression = | |||
|top_speed =150 mph | |||
|power = | |||
|torque = | |||
|fuel_system = | |||
|ignition = | |||
|spark_plug = | |||
|battery = | |||
|transmission = | |||
|frame = | |||
|suspension = | |||
|brakes = | |||
|front_tire = | |||
|rear_tire = | |||
|rake_trail = | |||
|wheelbase = | |||
|length = | |||
|width = | |||
|height = | |||
|seat_height = | |||
|dry_weight = | |||
|wet_weight = | |||
|fuel_capacity = | |||
|oil_capacity = | |||
|recommended_oil=Yamalube 10w-40 | |||
|fuel_consumption = | |||
|turning_radius = | |||
|related = | |||
|competition = | |||
}} | |||
[[Image:1974 Yamaha TZ700.jpg|200px|thumb|right|1974 Yamaha TZ700]] | |||
In 1974, [[Yamaha]] came out with its first-born [[2-stroke]], [[inline-four]] production road racer. The '''TZ700''' was a 90 [[hp]], 694[[cc]] [[engine]] that had the same 64mm bore size as the [[TZ350]] and [[RD350]]. It had twin shock rear suspension. In 1975, cylinder bore was increased to 66.4mm yielding 747cc, producing about 15 more hp. The rear suspension was also upgraded to [[Monoshock]]. | |||
==TZ750A (TZ700)== | |||
[[Image:1974 Yamaha TZ750A.jpg|right|thumb|1974 Yamaha TZ750A]] | |||
The first version of the TZ750 was not actually 750cc, but a 700. Yamaha simply doubled up their successful TZ350cc twin to create one of the most successful racing [[motorcycles]] that dominated open class racing for a period of ten years. The next version, the "B" model was at last a full 750, obtained by increasing the [[bore]] to 66.4 mm, with peak [[horsepower]] at 105. | |||
{{clear}} | |||
==TZ750F== | ==TZ750F== | ||
[[Image:1979 Yamaha TZ750.jpg|left|thumb|1979 Yamaha TZ750F]] | |||
The [[Yamaha]] 1979 TZ750 "F" [[motorcycle]] was the last version of the TZ750, and was virtually a replica of the OW-31 factory racers. A total of five hundred and sixty seven TZ750s were produced from 1973 to 1979. The "A" version was actually a 700cc, the cylinder bores were increased to give 747cc in 1975. | The [[Yamaha]] 1979 TZ750 "F" [[motorcycle]] was the last version of the TZ750, and was virtually a replica of the OW-31 factory racers. A total of five hundred and sixty seven TZ750s were produced from 1973 to 1979. The "A" version was actually a 700cc, the cylinder bores were increased to give 747cc in 1975. | ||
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[[Image:1979 Yamaha TZ750F.jpg|right|thumb|1979 Yamaha TZ750F]] | [[Image:1979 Yamaha TZ750F.jpg|right|thumb|1979 Yamaha TZ750F]] | ||
Georgia pig farmer, Dale Singleton, rode this TZ to victory in the 1981 [[Daytona 200]] Race. These big TZ's were the preferred [[motorcycles]] by the majority of racers of a span of six years until the regulations for the 750cc were changed, and specified [[four stroke]] motors only. The "F" model was the final version of the TZ750s. | Georgia pig farmer, Dale Singleton, rode this TZ to victory in the 1981 [[Daytona 200]] Race. These big TZ's were the preferred [[motorcycles]] by the majority of racers of a span of six years until the regulations for the 750cc were changed, and specified [[four stroke]] motors only. The "F" model was the final version of the TZ750s. | ||
{{clear}} | {{clear}} | ||
== Photos == | |||
[[File:Yamaha--TZ-750-01.jpg|600px|Racing Bikes Z750]] | |||
[[File:Yamaha-TZ750--1.jpg|600px|Racing Bikes Z750]] | |||
[[File:Yamaha-TZ750.jpg|600px|Racing Bikes Z750]] | |||
[[File:Yamaha-TZ-750.jpg|600px|Racing Bikes Z750]] | |||
[[File:Yamaha-TZ-750--1.jpg|600px|Racing Bikes Z750]] | |||
[[File:Yamaha-TZ750-79.jpg|600px|Racing Bikes Z750]] | |||
== Review == | |||
The official Yamaha 350 racer, Jarno Saarinen, rode to victory | |||
in the 1973 Imola 200 Miles after having won that year's Daytona 200. It was at | |||
the Imola race that motorcycle fans first got word of the four-cylinder Yamaha | |||
700, a new speed demon that had been built by the most famous manufacturer of | |||
international racing motorcycles to challenge the Suzuki and Kawasaki | |||
three-cylinder 750s. | |||
Saarinen was responsible for the publicity leak, although it was not all that | |||
indiscreet. The new Yamaha engine consisted of two 350-cc. racing engines put | |||
together. In tests it generated 140 h.p. | |||
The Yamaha 700 was tested secretly on the company's own track. | |||
Giacomo Agostini, who had joined the team, tried it out first after the test | |||
driver Hideo Kanaya had tuned it. Agostini had switched to Yamaha chiefly to | |||
race formula 750 in the | |||
United States. He rode the new 700 to win the 1974 Daytona 200 Miles and the | |||
Imola 200, sister race of the Daytona. From that moment on, the 750 class | |||
throughout the world was the exclusive property of official and private riders | |||
of the Yamaha, except for occasional sorties by Kawasaki and Suzuki. | |||
At first the four-cylinder 700 had an engine built by putting | |||
together a pair of two-cylinder Yamaha 350s with gill-port distribution. The | |||
engine generated some 115 h.p., making possible a top speed of about 185 m.p.h. | |||
The chassis had the classic double cradle with traditional suspension. | |||
Altogether the motorcycle weighed over 350 pounds, which was too much for a | |||
racing motorcycle. Agostini tried out an interesting chassis modification in | |||
order to improve the vehicle's maneuverability and stability. | |||
A rear suspension with triangulated Yamaha 700 Four-cylinder | |||
swinging fork was installed. The upper arm worked the single central shock | |||
absorber, which was mounted in a semihorizontal position under the fuel tank. | |||
The new type of suspension, called "monocross" or "cantilever," was installed on | |||
all subsequent Yamaha racers. In 1975 the TZ 700 became the TZ 750. It was not a | |||
question of merely increasing displacement, but involved an overhaul of both the | |||
engine and the chassis. The Yamaha Daytona had always looked bulky and clumsy, | |||
but after this overhauling it looked sleek and powerful. | |||
The Yamaha TZ 750 was unbeatable in formula 750 racing. Suzuki and Kawasaki | |||
turned out new models without being able to overtake it. | |||
Until the end of the 1976 season, Cecotto, Roberts, Romero, Agostini, and Victor | |||
PalomoFIM formula 750 champion in 1976rode official, private, or | |||
partially-assisted Yamaha TZ 750s. Thanks chiefly to its mechanical robustness | |||
and its 140 h.p., this motorcycle dominated the major speed races. | |||
Motorcycle: Yamaha TZ 750 (model OW 31, official 1976 version) Manufacturer: | |||
Yamaha Motor Co. Ltd., | |||
Type: Daytona and FIM formula 750 Year: 1976 | |||
Engine: Yamaha four-cylinder in-line, two-stroke, with cross-port distribution. | |||
Displacement 750 cc. (66 mm. x54 mm.) | |||
Cooling: Water | |||
Transmission: Six-speed block | |||
Power: About 140 h.p. at 10,700 r.p.m. | |||
Maximum speed: Over 185 m.p.h. | |||
Chassis: Double cradle, continuous, tubular. Front, telescopic fork suspension; | |||
rear, cantilever telescopic suspension | |||
Brakes: Front, double hydraulic disk; rear, single hydraulic disk | |||
1978 Review | |||
Close your eyes for a moment and try to visualize | |||
the ultimate café racer. What do you see? A tricked-our RD400? Not enough motor. | |||
Think bigger. What do you see now? A reworked Kawasaki 1000? Not enough | |||
handling. Try again, and think exotic. You see a Ducati Desmo 900? Not exotic | |||
enough, and too slow. Close your eyes again. Picture Kenny Roberts in 1974. | |||
Picture Kenny Roberts road racing. Now picture that kind of bike with a | |||
California license plate. What? A street legal TZ750? Totally outrageous? Yes. | |||
Sifting on a side street, you familiarize | |||
yourself with the TZ's controls. You remember that the shifting pattern has been | |||
converted to one-up, four-down. Across the Molly-striped tank, the clip-ons are | |||
fitted with the standard controls as well as an added mirror and light switches. | |||
The K&N filters on the outboard carbs crowd your knee-space, but thankfully they | |||
are somewhat flexible. Instrumentation consists of a water temperature gauge and | |||
a tachometer red-lined at 10,500. | |||
You flip on the ignition, check the petcock and | |||
get a push. Easing out the clutch, the engine springs to life. Instantly you are | |||
assaulted by mechanical noise: straight-cut gears, dry clutch and hissing | |||
intakesall funneled up by the fairing. You almost have to listen for the | |||
muffled exhaust note, but the unmistakable tone of a racing Yamaha four-cylinder | |||
is there. Blipping the throttle, the engine revs freely with no sign of | |||
hesitation. The clutch isn't grabby at all. More surprising is the amount of | |||
low-end torque available. The bike feels like a strong 500 and isn't the least | |||
bit fussy. Sifting at a stoplight the bike idles like your garden variety street | |||
bike. But looking down, you see a yellow TZ750. Your mind reelsyou should be | |||
gridding on a race track, not waiting to merge onto a freeway. | |||
Into traffic, and the bike rolls merrily along, | |||
content to go with the flow. The road clears up ahead, so you dial up some | |||
power. The tach hits eight and rockets to 12,500. Your heart stops at TDC. It's | |||
like being launched from an aircraft carrier. The front wheel begins to skip off | |||
the asphalt, spending equal time in the air. You're in trouble. The cars around | |||
you that were doing 55 mph seem to have suddenly stopped and parked. Those cars | |||
that were ahead, out of sight, are suddenly right here, and you haul down on all | |||
three discs. Off the main road and into the curves, and the TZ is ready. Heeling | |||
over, nothing scrapes. Braking is strong but smooth, progressive and fade-free. | |||
The bike does all you ask of it, and then some. Why not? It is, after all, a | |||
road racerand it's much better at going fast than you are. | |||
Putting a road racer on the street isn't quite as | |||
impossible a task as one might think. It doesn't require any political | |||
connections, bribes or even much money. But it does require a fantastic amount | |||
of patience. Joe Taormina had sufficient patience to complete the task, as well | |||
as a little help from his friends. The fact that Taormina is a mechanic at | |||
Yamaha of Pacific Beach, near San Diego, also helped. The manager, Bob | |||
Schaeffer, was quick to provide Joe with access to the shop on Sundays. Service | |||
manager 011ie Olivera and fellow mechanic Tom Zaragoza provided Joe with | |||
suggestions, advice and helping hands whenever needed. This sense of voluntary | |||
teamwork was typical of the project in general. Friends, acquaintances and | |||
customers alike were drawn toward the project, always willing to be of service. | |||
The creation of the street-legal TZ750 began as | |||
the typical quest for "something different." Taormina had been considering | |||
construction of a street-legal flat-tracker. Then he read an article in which | |||
Don Vesco alluded to the fact that someday he expected to see someone ride up on | |||
a TZ750. For Taormina, that was enough. | |||
Searching in the San Diego area soon yielded a | |||
somewhat thrashed TZ750 whose owner was retiring from racing. The price of $2900 | |||
was reasonable, but | |||
Taormina needed help. Banks and loan institutions | |||
weren't receptive; for some peculiar reason, they considered building a café | |||
racer untenable grounds for a loan. Undaunted, Taormina altered his premise for | |||
a loan to read as "funding for a research project for an experimental | |||
motorcycle." One banker finally accepted this line of reasoning, and Taormina | |||
was the new owner of a used TZ750. | |||
Stripping down the bike revealed the TZ to be in | |||
better condition than it appeared. Coolant had been leaking into the | |||
transmission, but this proved to be only a minor problem. A tube which routed | |||
water through the gearbox had been kinked and cracked. Replacement of seals and | |||
this tube constituted all of the necessary repairs. The transmission looked as | |||
good as new. Even the clutch plates and piston dimensions were within acceptable | |||
limits. The painstaking task of assembly could not ignore the State of | |||
California. The list of street-legal requirements set forth by the Department of | |||
Motor Vehicles in- cluded: an electrical system, complete with a battery and | |||
charging system; a brake light which would operate with a dead engine; turn | |||
signals; mirror; and horn. A headlight was not required but included in the | |||
plans. Taormina wanted to keep the TZ as close to its stock appearance as | |||
possible. Having seen too many other specials and custom bikes cluttered up with | |||
poor detailing, he was determined to make his modifications as unobtrusive as | |||
possible. To do it right would take a lot of time. | |||
As Taormina worked in the shop on customers | |||
bikes, he would develop mental pictures of alternatives for fitting in the extra | |||
parts. By picking up ideas here and there, trying some, keeping a few and | |||
discarding most of them, the bike began to come together. The biggest obstacle | |||
was locating a lighting system. The wiring harness from a DT 400 looked like it | |||
would work perfectly, but its tight-fitting CDI unit couldn't handle the | |||
12,000-rpm engine speeds and would produce too much flywheel effect. The R5 350 | |||
alternator system wouldn't work without modifying the side case. Finally, a call | |||
to Weda instruments in Aurora, Oregon produced results. Known primarily for | |||
their off-road lighting kits, they were willing to tackle Taorrnina's lighting | |||
dilemma. The cornpany was able to develop a unit which worked off the existing | |||
T7 unit. By tapping the source coils in the CDI, the solid-state unit would | |||
charge a 12-volt battery at the rate of one amphour, without affecting the | |||
ignition system. The small Weda unit was easily hidden away and the battery was | |||
tucked in under the tail section. The stock DT 400 key switch was discretely | |||
situated under the seat, while a stock set of Yamaha switches provided | |||
finger-tip accessibility. Fitting the light switches on the short clip-on | |||
handlebars required relocating the choke lever by attaching it to the steering | |||
damper. | |||
While the electrical system was being | |||
straightened out, Taormina stripped the frame, added tabs for the sidestand, | |||
etc., and then repainted the chassis. The tank, fairing and tail section were in | |||
serviceable condition but in need of a new coat of paint. Dave Harris, a former | |||
customer, volunteered to undertake the task. Harris had given up flattracking | |||
and was going back to school. He was, however, still doing painting in his | |||
garage. They chose to model the bike after Kenny Roberts' 1974-1975 racer. | |||
Harris' execution was flawless; the bike turned out to be a virtual replica. | |||
Installing the glasswork, lighting, horn and | |||
mirror left only one major taskinstalling mufflers. Taormina chose Supertrapp | |||
silencers from Discojet. These silencers can be tuned for backpressure and/or | |||
loudness by adding or removing plated discs. Stacking more discs increases | |||
loudness while relieving back pressure, while removing discs does the opposite. | |||
Martin Specialties in nearby Spring Valley cut and welded the pipes and mufflers | |||
to achieve the appearance Taormina desired, while maintaining the Ground Clearance and strength necessary. After repositioning the four mufflers | |||
innumerable times, they arrived at the correct combination. Once together and | |||
running, the only modification necessary was the replacement of the carburetor | |||
slides. Taormina replaced the racing slides with standard Mikuni slides. He | |||
drilled and tapped holes for idle screws on the four carb bodies, and he now had | |||
a TZ750 that would be streetable and street-legal. The hard part was overor so | |||
he thought. | |||
Taking the bike down to the Department of Motor | |||
Vehicles, Taormina began a series of confrontations with the bureaucracy of the | |||
State of California. The person behind the registration counter at the D.M.V. | |||
listened to Taormina's proposal. Sorry, he was told, but the Yamaha TZ750B was a | |||
racing machine and was on the list of motorcycles deemed "unlicensable." He | |||
pointed out that his TZ was a TZ750A model, not a "B" model. After much | |||
discussion with the person in charge, the D.M.V. countered that ploy with one of | |||
their own: they added the TZ750A to their "black list." Attempting another line | |||
of attack, Taormina asked them what he had to do to make it legal. If he had | |||
constructed a trailer from scratch, for example, he could just follow D.M.V. | |||
guidelines to make it legal and license it. Why couldn't he just do that with | |||
the TZ? After extended hemming and hawing, the D.M.V. people did the logical | |||
thing and passed the buck. They said it was up to "Sacramento." | |||
Calling up the main office in Sacramento produced | |||
more excuses. They couldn't explain why not; they just knew he couldn't. They | |||
gave no logical or rational argument; just a flat no. Being the patient sort, | |||
Taormina countered again with the suggestion that if the TZ was up to acceptable | |||
specifications, he should be able to operate it on public roads. The D.M.V. | |||
people, with no logical course of action, carried through with their form of | |||
logic and passed the buck again. They agreed, with no lack of snickering and | |||
eye-rolling, that if the California Highway Patrol would certify that the TZ was | |||
indeed up to Vehicle Code specifications, they would license it. Their | |||
understanding, of course, was that the CHP would reject the bike and settle the | |||
matter once and for all. On his way out, Taormina vowed to himself that he would | |||
be back to beat them at their own game. After three weeks of phoning the CHP, | |||
Taormina arranged for a vehicle inspection. The inspection would take place in | |||
the San Diego Stadium parking lot and would include tests with a sound-level meter. | |||
The morning of the test, Taormina arrived at the | |||
stadium to find four patrolmen present, bristling with code books. Their | |||
attitudes ranged from interested and sympathetic to hard-nosed and antagonistic. | |||
However, they were all there to do their jobto make sure the TZ met all | |||
regulations. First, they checked all bulbs and the taillight to insure they | |||
carried the approved D.O.T. numbers. They were all legal. Next, they examined | |||
the electrical system. Battery? Located under the tail section. Charging system? | |||
Taormina produced schematic diagrams and offered to take voltage readings. The | |||
electrics were approved, as were horn, mirror and signals. The TZ had passed all | |||
tests, save onethe sound test. | |||
The test requires that a motorcycle be operated | |||
at 80 per cent throttle in second gear as it passes the sound-level meter. The | |||
meter is located 50 feet away from the motorcycle's path, at a 90-degree angle | |||
to the direction of travel. As Taormina made his first pass, an officer | |||
signalled him to down-shift. Due to the TZ's high gearing, they assumed that he | |||
was in too high of a gear. Assured that he was in second gear, Taormina made | |||
another pass. The reading was 106dB(A). Sorry, he was told, but the legal limit | |||
was 84dB(A). | |||
Disappointed but undaunted, Taormina began | |||
working on the bike. Contacting Discojet, he explained his problem. They | |||
suggested using their "quiet core" kit and reducing the number of plates in the | |||
muffler. After making these modifications, he arranged for another test date. | |||
Meanwhile, he had borrowed a $300 industrial sound-level meter, which was used | |||
for meeting OSHA sound regulations. Taking his own sound readings, Taormina had | |||
recorded his TZ at 82dB(A). | |||
At the second test, Taormina brought along | |||
friends to take sound readings and to check what the CHP meter was reading. | |||
Making his second gear pass, the borrowed meter read 82dB(A), but the CHP meter | |||
read 92dB(A). Sorry, the officers said, they had to go by their own meter. | |||
Failing the second time only made Taormina that | |||
much more determined to pass the sound test. This time he took all but one plate | |||
out of the muffler. He wrapped the pipes in asbestos. He built a foam-lined air | |||
box to muffle intake noise. He mounted the fairing to shield the engine noise. | |||
He was ready to try again. | |||
The third test proved to be worse. His | |||
modifications actually made the motorcycle louder by redirecting the noise. | |||
After three tests and nine weeks of work, it seemed that it would be impossible | |||
to pass the noise tests. The TZ was a racing bike indeed, and it just made too | |||
much mechanical noise to pass. Taormina took his final recourse. He stuffed the | |||
pipes. With fiberglass restricting the exhaust pipes, the engine wouldn't rev | |||
past 6000 rpm, but it was quiet enough to pass at 86dB(A). One CHP officer | |||
pointed out that 84dB(A) was all that was necessary since the bike was a 1974 | |||
motorcycle and therefore subject only to 1974 regulations. The bike was | |||
certified. Before departing, the one officer who was the most zealous of the | |||
group took Taormina aside. The officer reminded him that the motorcycle had to | |||
be kept in this exact form; if one thing was changed, it would be in violation | |||
of the state vehicle code and be subject to citation. Taormina replied that he | |||
realized this and thanked him for the reminder. | |||
On the way home, Taormina stopped by the DMV for | |||
licensing. It was, to say the least, .an eminently satisfying experience. With | |||
his temporary license in hand, he went home and did what any red-blooded, | |||
all-American citizen and café rider would do. He unstuffed the pipes, removed | |||
all the excess sound insulation and signals and went riding. He hasn't been | |||
stopped since. | |||
Source Cycle 1979 | |||
{{Yamaha}} | |||
[[Category:Yamaha motorcycles]] | [[Category:Yamaha motorcycles]] | ||
[[Category:Yamaha TZ series]] | |||
[[Category:Racing motorcycles]] |