With the TDR, Yamaha create a totally new category in motorcycling. Powered by a two-stroke parallel-twin engine with YPVS and "cross-up" exhaust system, the TDR boosts instant acceleration far exceeding that of normal dual-purpose machines. The TDR is also the world's first two-stroke bike to use a CD ignition with digital advance system.

Nimble handling and stunning acceleration for street use are combined with unmatched off-road capabilities, thanks to sturdy front forks, the rising-rate Monocross rear suspension, and front and rear disc brakes.
And as for looks, a tank-mounted head fairing rounds out the TDR's unique styling theme. The 250cc class will never again be the same.

Styling was influenced by off-road
TECHNICAL HIGHLIGHTS
• Powerful 249 cc, 2-stroke, parallel twin-cylinder engine with liquid cooling, YPVS and crankcase reed-valve induction
• Combination of CDI and digital timing advance system
• High-efficiency "cross-up" exhaust system
• Air-assisted front fork and rising-rate Monocross rear suspension system
• Front and rear disc brakes and dual-purpose tyres
• Unique styling and aerodynamic head fairing


The 2 stroke twin was based on TZR 250 street sports and delivered 50 HP

A tubular steel frame with a high mounted headstock gave agile handling on the road and ensured some offroad capability too

Unusual: the cockpit with revcounter mounted on top of the fuel tank
TECHNICAL FEATURES

Engine

While essentially a TZR25O unit, a variety of modifications have been made to better suit engine power delivery with intended use. Lowered first gear ratio (45/14 against the TZR25O's 4 1/14) dramatically improves acceleration while increasing off-road traction. Power is transmitted to the rear wheel via a sealed, continuous-link chain for high durability and low maintenance.

The newly designed "cross-up" exhaust system, featuring "satellite-chrome" plated silencers, is tuned for low- and mid-range power. lt ensures plenty of ground clearance and free rider movement. The 28 mm flat-slide carburetors have been re-jetted to match the different breathing requirements of the new pipe and airbox.
The TDR is the world's first motorcycle to combine a CD ignition with a digital timing advance system. Controlled by a 4-bit microprocessor, it ensures perfect ignition timing at all rpm. The microcomputer also serves as a control unit for the YPVS and side-stand switch, contributing to savings in weight and space.

Aside from the above modifications and new silver paint, the TDR engine shares all the virtues of the TZR unit: efficient case-reed induction with fibre reeds and 28 mm flat-slide carbs; YPVS; sealed liquid-cooling system with lightweight radiator and coolant passageways around the exhaust ports; and Autolube oil injection with YPVS-controlled pump. The TDR also shares the TZR's orthogonal engine mounting system which reduces vibration.

This high-powered stormer will soon be the "quickest bike in town." Maximum speed will exceed 100 mph - quite impressive, when one considers the upright riding position. (A 240 cc version will be sold in France to meet local requirements.)

Frame
Fabricated of high-tensile steel tubes, the double-cradle frame features high strength and low weight. Both the top- and downtubes are narrowly spaced near the steering head to permit a wide steering angle, and extensive gussettings are used at this point for increased rigidity. Tapered roller bearings are used at the steering head for increased durability and reduced flexing. Cast-aluminium passenger footrest brackets are mounted on the rear sub-frame.

Suspension
An air-assisted, centre-axle front fork uses stiff 38 mm stanchions.
A steep 27-degree castor angle and 114 mm of trail contribute to the TDR's short wheelbase and quick-handling characteristics. Front wheel travel is 160 mm. The fork is adjustable for air pressure and spring pre-load, and is fitted with rubber gaiters to protect the tubes from debris.
The rising-rate Monocross rear Suspension system features a De Carbon-type gas/oil shock absorber with separate reservoir operated by a box-section swinging arm of high-tensile steel. Rear wheel travel is 150 mm.
This suspension System is designed to provide an idealized compromise between on- and off-road riding - with a slight street bias.

Brakes
The TDR uses front and rear disc brakes. The front disc is a 320 mm floating unit operated by a 4-pot, opposed-piston caliper, while a 210 mm disc with opposed-piston caliper is used at the rear (the discs are same as the TZR's).

Fairing, Instrumentation, Fuel Tank and Seat
Another unique feature of the TDR is its stylish tank-mounted head fairing. Tank mounting frees the front end of excessive weight for light handling while ensuring free rider movement. A square, 60/55W halogen headlamp is used, and the turn indicators are mounted on flexible rubber stalks. Inside the fairing are located the water temperature gauge and indicator lamps, while the speedometer is positioned right in front of the steering head. The tachometer is situated at the front of the fuel tank. This design minimizes inertia moment at the front end. The 14-litre fuel tank has an aircraft-style cap and automatic, negative pressure-activated fuel tap. The seat features thick padding and roominess, with the oil tank, airbox, tool and glove boxes underneath. The ignition key is used to unlock the seat. A pair of grab-rails are fitted on the rear cowl.

Wheels and Tyres
The 18-inch front and 17-inch rear spoked wheels have light aluminum rims and will be fitted with either Metzeler Enduro 3 Sahara or Bridgestone Trail Wing tyres for good traction on both tarmac and dirt. The low front fender directs cooling air to the radiator.
The Yamaha TDR - adding a new dimension to the already exciting field of sport riding.

1988 press kit Feature Map

TDR FEATURES

1) 2-stroke, 249 cc, liquid-cooled, crankcase reed-valve, parallel twin-cylinder engine.
• Yamaha Power Valve System (YPVS)
• Mikuni TM28SS flat-slide carburetors and fibre reeds
• Low secondary reduction for increased traction
• Sealed, continuous-link drive chain
• Sealed cooling system with alloy radiator & coolant passage around exhaust ports
• Autolube oil injection System with microcomputer-controlled oil pump
• Yamaha's "orthogonal" engine mounting for reduced vibration

2) Capacitor discharge ignition with microcomputer-controlled, digital timing advance System.
3) "Cross-up"lt's a muscle bike like no other. Designed exclusively for America, not only to look good, but to deliver all the horsepower Americans ever dreamed of. It'll accelerate fast enough to shift the motorcycling world on its axis. We're talking raw power here and the rugged good looks that let everyone know you mean business. The aggressive styling could have come straight from the very best Custom shops.

In back there is motorcycling's biggest rear tire: a 150/90-15 monster that looks big enough for a dragster. lt's wrapped around a new disc-type solid aluminium wheel that looks sharper than any custom wheel around. The rear end's set off by a skinnier front tire mounted on a 5-spoke 18-inch wheel. Both ends are covered by chopped fenders and accented by deep chrome. There's even a three-piece stepped seat with a lockable center section that pivots forward to reveal the filler for an under-seat fuel tank that helps keep the V-Max's center of gravity low. Between the bars is a chrome and gold speedometer: nothing else. Where the fuel is stored on other motorcycles there's a large air filter providing improved air flow to downdraft carbs. Mounted in a panel above the air filter cover is a rev counter and a temperature gauge. There are lots of other good looking features to impress everyone down at the drive-in, but when the V-MAX starts rolling it's the incredible motor that will turn the heads. This 1198cc monster produces power like nothing else before it, thanks in part to a radical cam and four massive valves per cylinder. Short ecliptical mufflers do their part to boost power and let everyone know it too. But what really gets this hot rod screaming is a unique new V-Boost System. At lower rpm each of the four downdraft carburettors feeds its own cylinder. But as the revs rise a servo motor opens a butterfly valve between each pair of inlet tracts. Suddenly there are tow carbs feeding each inlet port on an intake stroke. lt's like having a blower without all the mechanical losses. If anyone's unsure about the V-MAX's powerful potential there are chrome and polished-aluminium highlights that trace the power flow from the large air scoops below the tank, through the motor and out the exhaust.

For anyone just looking the V-MAX spells power. Anyone that rides motorcycling's first real hot rod will know that those looks aren't deceptive. Motorcycling finally has the power and it took Yamaha's hot-rod V-MAX to move motorcycling one major step forward.


FEATURES

Tires
The world's largest production-bike tire is used in rear. lt is a V-rated 150/90-15 with a V-pattern tread.

Shaft Drive
A newly designed shaft drive with stronger bevel gears transmits the V-MAX's tremendous power.

FueI Tank
A 4-gallon fuel tank is mounted below the seat. Fuel is delivered by an electric pump and an electric reserve switch is mounted on the handlebars.

Frame
The tubular steel frame has a specially lowered center section to reduce seat height. The right front downtube and left rear frame tube are removable to ease maintenance.

Shocks
Dual rear shocks have four-way adjustable rebound damping and five preload positions for the massive chrome springs. Wheel travel is 100 mm.

Fork
A large 40 mm fork is air adjustable and has a balance pipe for ease of adjustment. An integrated aluminium fork brace increases front-end stability. Wheel travel is 140 mm.

Brakes
Triple ventilated disc rotors-282mm diameter-are gripped by large 45mm opposed pistons.

Wheels
A newly designed 18-inch cast wheel is used in front. A radical 15-inch solid disc wheel is used in rear.

Seat
The V-MAX has a 3-piece stepped seat design. The lockable center section pivots forward to provide access to the fuel filler cap.

Controls
All handlebar controls are finished in silver.

Gauges
A single speedometer is mounted above the triple clamps. Separate tachometer and temperature gauge are mounted on a tank-top panel. All gauges have white faces.

Air Filter
Air filter, fuses and hydraulic reservoir are mounted under a lockable false-tank panel.

Cable Covers
Chromed springs cover the control cables.

Headlight
A small circular headlight is used.

Air Ducts
Air ducts above the cylinders help to highlight the flow of power from the intake system, through the motor and out of the exhaust system.

Motor
Engine The 1198 cc liquid-cooled V-Four engine has double overhead camshafts and four valves per cylinder.

Piston
A specially lightened piston and wrist pin improve engine performance.

Crankshaft
A new hardening and heat treatment process improve crankshaft and con rod strength.

Valves
Large 30.5mm intake and 25.0mm exhaust valves are controlled by stronger valve springs.

Camshaft
A special high-performance high-lift camshaft is designed to produce maximum horsepower.

V-Boost
A unique V-Boost System gives a Turbo-like power boost to the V-MAX motor. Four downdraft carburetors feed the cylinders through individual inlet tracts. However, the tracts between cylinders one and two and cylinders three and four are separated by butterfly valves. The valves are controlled by servo motors that measure engine rpm. At approximately 6000 rpm the servos start to open the butterfly valves until they are completely open at 8000 rpm. With the butterfly valves open each cylinder on an intake stroke is fed by two carburetors, rather than a more conventional single unit. Horsepower is considerably increased especially in the mid-and high-rpm range.

Transmission
Power is transmitted through a five-speed gearbox and a shaft final drive.

Muffler
Short ecliptical mufflers help to maximize power output.

Carburetors
Four 35mm downdraft Mikuni carburetors mix fuel for the V-MAX motor.
exhaust system featuring satellite -chromed silencers.
4) Light, strong double-cradle frame fabricated of high-tensile steel tubes. Tapered roller bearings are used at the steering head.
5) Sturdy 38 mm front fork is adjustable for air pressure and spring pre-load. Provides 160 mm of wheel travel.
6) Rising-rate Monocross rear suspension uses a De Carbon-type gas/oil damper and a box-section, high-tensile steel swinging arm. Rear wheel travel is 150 mm.
7) A drilled, 320 mm front disc stopped by a 4-pot, opposed-piston caliper. The rotor is floating for precise control.
8) The rear brake consists of a drilled, 210 mm disc and an opposed-piston caliper.
9) Stylish head fairing is mounted to the petrol tank for nimble handling. lt houses a powerful 60/55W halogen headlamp.
10) Simplified instrument panel features tank-mounted tachometer for easy reading.
11) The tank holds 14 litres of petrol and uses an aircraft-style filler cap and a negative pressure activated tap.
12) Roomy, deeply padded seat is 820 mm from the ground. Separate passenger grab bars are fitted to the tail cowl. The oil tank, air filter, tool and glove boxes are situated beneath the seat.
13) 18" front and 17" rear spoked wheels have aluminum rims, and are shod with Metzeler or Bridgestone high-grip tyres. Low front fender helps cooling efficiency.
14) Lightweight cast-aluminium pillion footrest brackets.

Source yamaha-motor.de