Yamaha TDR 250

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" 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 liters 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