The RD LC's

 

These bikes followed the successful air cooled RD series of the 70's. The first LC's arrived in 1980 with the RD350LC, aimed at the European market along with the smaller capacity Learner Legal RD250LC, the RD350LC had a parallel twin two-stroke engine with identical bore and stroke of its predecessor Yamaha RD350. However, Yamaha added liquid cooling and made other modifications in porting and exhaust to comply with the ever tightening emission regulations.  The 1980 to 1982 350 cc models were codenamed 4L0 and are affectionately known as Elsie, It was considered a fire breather in its time and was favourite with thte Wheelie brigade and was the most stolen bike of the time !  In 1983 Yamaha  debuted their breakthrough YPVS power valve system that revolutionized the two-stroke engine in the RD350 YPVS

 

With the success in the early 1980s of Kenny Roberts 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. 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 dual crankshafts are geared directly to the clutch, while the front crankshaft also drives a counter balancer shaft mounted between the two crankshafts. The counterbalance 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). 

 

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 frame 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 RD500LC uses 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.