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1988 Yamaha press information

TDR Features
TDR 250:in 1988 a class of it's own
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.
TDR 250 1988 model
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 on-off
* 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.


While essentially a TZR 25O 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 TZR 25O'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. It ensures plenty of ground clearance and free rider movement. The 28 mm flat-slide carburettors have been re-jetted to match the different breathing requirements of the new pipe and air box.

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


Fabricated of high-tensile steel tubes, the double-cradle frame features high strength and low weight. Both the top and down tubes are narrowly spaced near the steering head to permit a wide steering angle, and extensive gusseting 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.

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 calliper, while a 210 mm disc with opposed-piston calliper is used at the rear (the discs are same as the TZR's).
Unusual: the cockpit with revcounter
mounted on top of the fuel tank

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, air box, 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 aluminium 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

1) 2-stroke, 249 cc, liquid-cooled, crankcase reed-valve, parallel twin-cylinder engine.
* Yamaha Power Valve System (YPVS)
* Mikuni TM28SS flat-slide carburettors 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 calliper. The rotor is floating for precise control.
8) The rear brake consists of a drilled, 210 mm disc and an opposed-piston calliper.
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 aluminium rims, and are shod with Metzeler or Bridgestone high-grip tyres. Low front fender helps cooling efficiency.
14) Lightweight cast-aluminium pillion footrest brackets.



[ ] = French model

Type 2-stroke, liquid-cooled, crankcase reed-valve, parallel
Displacement 249 cc [239 cc]
Bore and stroke 56.4 x 50.0 mm [55.2 x 50.0 mm]
Compression ratio 5.9:1 [5.7:11
Maximum power (DIN) 50.3 PS (37.1 kW) @l0,000 rpm
[44.3 Ps (32.6 kW) @10,000 rpm]
Maximum torque (DIN) 3.7 kg-m (36.2 Nm) @8,500 rpm
[3.5 kg-m (34.6 Nm) @9,500 rpm]
Carburetion Mikuni TM28SS x 2
Ignition Capacitor discharge, with digital timing advance
Starting Kick
Lubrication Autolube oil injection
Oil tank capacity 1 .4 litres

Type 6-speed, constant-mesh
Primary reduction ratio .... 5 6/22 (2.545)
Secondary reduction ratio . . 45/14 (3.214)
Gear ratio, 1st 36/14 (2.571)
Gearratio,2nd 28/16 (1.750)
Gearratio,3rd 25/19 (1.316)
Gearratio,4th 26/24(1.083)
Gear ratio, 5th 25/26 (0.962)
Gear ratio, 6th 23/27 (0.852)
Clutch type Wet, multi-plate
Final drive Chain

Overall length 2,145 mm
Overall width 785 mm
Overall height 1,2 15 mm
Wheelbase 1,385 mm
Minimum ground clearance 230 mm

Overall length 2,145 mm
Overall width 785 mm
Overall height 1,2 15 mm
Wheelbase 1,385 mm
Minimum ground clearance 230 mm
Seat height 820 mm
Dry weight 137 kg
Fuel tank capacity 14.0 litres

Front Telescopic fork (160 mm travel)
Rear Rising-rate Monocross (150 mm travel)

Front Hydraulic disc, with 320 mm floating disc and 4-pot opposed-piston calliper
Rear Hydraulic disc, with 210 mm disc and opposed-piston calliper

Front 100/90-18H
Rear 120/80-17H

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