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