Yamaha RD500LC
Development
With the success in the early 1980s of Kenny Roberts and the Yamaha YZR500 in Grand Prix motorcycle racing Yamaha realised that a road going replica of their 500 cc racing machine would sell well. Using the similar technology of the smaller RD series of two stroke motorcycles the RD500LC was launched in 1984 to an enthusiastic riding public.
Design
Engine
Yamaha YZR500.
The RD500LC uses a 50-degree, twin-crankshaft V4 engine layout. Linked Yamaha YPVS exhaust power valves are controlled by a single electronic unit and servo motor and are designed to give a broader power band. The engine also featured intake reed valves unlike the YZR500 racer which used rotary disc valve induction. The reed valves used two different intake arrangements, the lower cylinders were fed through crankcase mounted reeds; the upper pair used cylinder barrel mounted reeds. The four Mikuni carburettors are side mounted in pairs and feed each cylinder through 90 degree intake manifold. The lower expansion chambers exit normally but the upper pipes cross over each other just behind the exhaust ports to maintain the correct tuned length. The dual crankshafts are geared directly to the clutch, while the front crankshaft also drives a counter balancer shaft mounted between the two crankshafts. The counter balance shaft, unusual on a two-stroke, assists with dampening engine vibrations. The engine is cooled by thermostatically controlled liquid cooling, an auxiliary electric fan mounted behind the radiator cuts in at high temperatures (e.g. when stationary in traffic). Lubrication is by direct injection in to the inlet manifolds using Yamaha’s ‘Autolube’ pump system, normally controlled in other two-stroke engines by throttle position the engine oil pump is controlled by the YPVS servo motor ensuring that the oil supply is not shut off at high engine revolutions.
Transmission
RD500LC rear view
The RD500LC uses a six speed sequential close ratio gearbox, the gear shafts are removable from the right side of the engine without the need to split the crankcases. The clutch is of the wet, multiple-disc coil spring type and is cable operated. Unusually for a two-stroke engine the gears and outer crankshaft bearings are lubricated by a separate crankshaft driven troichoid oil pump. Final drive is by O-ring chain and sprockets.
Chassis
The frame of the RD500LC is manufactured from mild steel box-section and uses a perimeter layout. The rear shock absorber is unusually placed horizontally under the engine and uses the lower crankcase as a mounting point. The under-seat area is occupied by the upper cylinder exhaust chambers, the battery and the YPVS servo motor. The rear of the shock absorber connects to an extruded aluminium alloy swinging arm via several forged aluminium rocker arms. An unusually small diameter 16″ wheel is held between 37 mm (1.5 in) spring and oil damped forks
which featured adjustable anti-dive units. The RD500LC used twin ventilated disc brakes for the front wheel with a single ventilated disc at the rear. A solo seat cowl was originally provided to cover the pillion seat when not in use.
Electrical system
RD500LC Speedometer and Tachometer
The RD500LC features a standard 12 volt electrical system. Yamaha’s self cancelling indicator unit is used and a variable resistance gauging system is used to monitor two-stroke oil tank contents with associated warning lights. Nippondenso Capacitor Discharge Ignition (CDI) is used in conjunction with two coils.
RZV500R
The RZV500R was designed exclusively for the Japanese home market although many have been exported privately. The RZV500R features upgraded parts not found on the standard RD500LC. A major difference is the hand-welded aluminium frame, which is significantly lighter than the steel version used on standard models. The front brake lines are braided stainless steel instead of rubber coated, and the front forks are air assisted with rebound damping adjustment. The rear brake and gear levers are cast from aluminium, as are the clip-on type handle bars. These chassis modifications added up to a weight saving of 20 lb (9.1 kg). The engine was detuned to 64 hp (48 kW) to comply with Japanese legislation, this was achieved by restricting the internal diameter of the exhaust pipes.
Models by country
Differences mentioned are comparisons to the UK specification RD500LC, Yamaha model numbers are in brackets where known.
Australia
RZ500N (52X)
Austria
Front and rear yellow side reflectors
Canada
RZ500S (1VW)
Denmark
Self retracting sidestand, right dip headlight
Finland
Self retracting side stand, extended rear mudguard, right dip headlight
Germany
Reduced load capacity (205kg instead of 211kg), self cancelling indicators deleted, right dip headlight
Japan
RZV500R (51X)
Norway
Self retracting sidestand, suppressor spark plug caps, right dip headlight
Sweden
Modified exhaust pipes, self retracting sidestand, right dip headlight
United Kingdom
RD500LC (47X early models – 1GE late models)
Specifications (RD500LC/RZV500R)
RD500LC
RZV500R
Engine
499 cc (30 cu in), 2-stroke, four-cylinder, liquid-cooled, reed valve induction with YPVS
499 cc (30 cu in), 2-stroke, four-cylinder, liquid-cooled, reed valve induction with YPVS
Bore Stroke
56.4 x 50.0 mm
56.4 x 50.0 mm
Compression Ratio
6.6:1
6.6:1
Fuel System
Mikuni VM26SS 26 mm (1.0 in) carburettor x 4
Mikuni VM26SS 26 mm (1.0 in) carburettor x 4
Lubrication
Yamaha Autolube two stroke injection, transmission gear pump.
Ignition
Capacitor Discharge Ignition (CDI)
Transmission
6-speed, constant mesh
Final Drive
530 chain, 102 links
Overall Length
2,085 mm (82.1 in)
2,085 mm (82.1 in)
Overall Width
705 mm (27.8 in)
Overall Height
1,145 mm (45.1 in)
1,145 mm (45.1 in)
Seat Height
780 mm (30.7 in)
Ground Clearance
145 mm (5.7 in)
Wheelbase
1,375 mm (54.1 in)
Dry Weight
205 kg (450 lb)
196 kg (430 lb)
Suspension Front
Telescopic, coil spring, non adjustable spring preload, brake linked anti-dive system
Telescopic, air assisted coil spring, adjustable spring preload, adjustable rebound damping with brake linked anti-dive system
Suspension Rear
Link-type, gas/oil damped, 5-way adjustable spring preload, 4-way adjustable rebound damping
Link-type, gas/oil damped, 5-way adjustable spring preload, 4-way adjustable rebound damping
Brakes Front
Dual hydraulic disc
Brakes Rear
Single hydraulic disc
Tires Front
120/80-VR16
Tires Rear
130/80-VR18
Fuel Tank Capacity
22 L (6 US gal; 5 imp gal)
22 L (6 US gal; 5 imp gal)
Colours
RD500LC: Stormy Red/Silky White, Silver frame, Stormy Red/New Yamaha Black, Special ‘Marlboro’ scheme (Limited Edition).RZ500: Chappy Red/Clean White, Silver frame (different pattern to RD500LC)
Chappy Red/Clean White, (pattern as RZ500) Silver frame
See also
List of Yamaha motorcycles
References
Notes
^ a b c d e f Motorcycle.com
^ Yamaha Service manual
^ a b c Yamaha service manual
References
Yamaha RD500LC (47X) service manual, Yamaha Motor Co. Ltd 1st edition, June 1984
Yamaha RD500LC (1GE-Europe) parts manual, Yamaha Motor Co.Ltd, 1985
Motorcycle.com The Grand Prix fantasy
External links
How stuff works – RZ500
1/12 scale model of RZV500R by Tamiya
Categories: Yamaha motorcycles
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