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Yamaha RD 350 YPVS

Raaaangbrabbelbrabbel

The two-stroke sting was deep in the fat four-stroke meat. Yamaha held the "Rangdang" flag up the longest of the major manufacturers. And gave the RD fans the thrilling YPVS series.

It was the biblical story of David versus Goliath that caught our imagination. And of course a shot of Robin Hood. In the end even the last Mohican, mixed with the old chief’s saying: Only when the last stinking two-stroke flag has driven its way into the eternal hunting grounds, you will notice that four-strokes are not really fast. Or something like that. The fact was: we wanted to be quick and we had no money. Built for guys like that Yamaha the rd models. Simple two-cylinder two-stroke, air-cooled, relatively robust, easy to screw and, above all, one thing: light. 170 kilos, with a full tank, of course, that was a word. The enemy was called Honda. This four-stroke company that flooded the world with their admittedly very good, but far too heavy CBs. And then the Gold Wing! How amused we were when we met such a cardan leg in the wild. You could drive circles around it. But the four-stroke engines caught up powerfully. Four-valve engine, better suspension, water cooling, full performance, that gave food for thought. Yamaha followed follows. The RD also switched to water cooling and went one better in 1983 with the 350 YPVS. Purest Grand Prix technology with the Power Valve exhaust control, 59 hp and still 170 kilos light. A dream and the star of this story, from a technical point of view, Yamaha tried to overcome the weaknesses typical of the two-stroke cycle. Inlet membranes already improved the filling of the cylinders in the air-cooled models. Now the exhaust control also shifted the exhaust timing. At low speeds, rollers closed part of the channel and thus ensured tamer control times. That made the engine surprisingly powerful and manageable underneath. The rollers opened from about 6000 rpm. ?? Zssssstzssssst ?? the YPVS sounds when the ignition key is turned. Clean the rollers once please. Don’t kick the Kickstarter down too hectically? raaaangbrabbelbrabbel ?? the cold engine stinks into the world. Get out of here before the fire department arrives. An RD cold start knocks out more unburned hydrocarbons than ten Hondas today all year round. I almost forgot. After a few hundred meters, the flag slowly disappears and the engine reaches operating temperature. The adventure can begin. It starts at just over 5000 rpm. At this speed, the previously brave everyday engine turns into a wild fellow who only wants one thing: to turn. The tachometer needle clicks wildly into the red area at 10,000 rpm, and the RD driver has to hold on to the wide and surprisingly high handlebars. No other engine can go off so mercilessly as a nearly inertia-free and valvetrain-free two-stroke. All he has to do is move the two pistons with the connecting rods to turn the crankshaft. High internal friction from camshafts, spring-loaded valves, just the whole four-stroke Kladderadatsch, an RD simply doesn’t have that.

Final: famous motorcycles

Yamaha RD 350 YPVS

Brakes, driving experience, chassis

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Two-stroke flag for a cold start, the racetrack in front of the front wheel, that’s what motorcycle dreams looked like in the early 80s.

You can tell when braking. Or shortly before, when taking off the gas. There is hardly any engine brake. That makes it incredibly fast before the curve and has to be learned again. So such a small two-stroke is actually incredibly efficient. If it weren’t for the problem of fresh gas losses. No engineer in the world has managed to create a two-stroke ?? except marine diesel? To be built in such a way that, over the entire speed range, it emits exactly only the burned gases and not also fresh gas, i.e. unburned gasoline-air mixture. That not only gave the two-stroke engine a good thirst, but also put it up against the wall pretty quickly in terms of emissions. Too bad. A fast moving 350 can easily treat itself to nine liters, in the MOTORRAD endurance test 1984 it was an average of 7.2 liters per 100 kilometers. Too much. But that shouldn’t burden us here. We were on the adventure. And there the Yamaha offers another peculiarity besides the fiery engine.

High-speed commuting, and the worst kind. The handlebar-fixed, small fairing provides a solid lift. In combination with a soft suspension set-up and a static weight of only 80 kilograms on the front wheel, that made the RD run pretty hard. The Yamaha people really worked hard on the chassis. The frame is similar to the TZ racing machines, the fork is air-assisted, and the central spring strut is articulated via a lever system called monocross. Ultimately, only a radical cure helped against commuting. 1985 the stable driving RD 350 F with full fairing came onto the market. And yet: with its great handiness, a courageously controlled RD 350 YPVS could stand up to many contemporary big bikes. At that time these were just iron piles. And mostly wobbled quite a bit too. They were also expensive. What does a Yamaha RD 350 YPVS cost? The equivalent of 2985 euros! We could also afford this little sting.

Technical data – Yamaha RD 350 YPVS

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Engine:
Water-cooled two-cylinder two-stroke engine, membrane inlet, power valve outlet control, bore x stroke 64 x 54 millimeters, 347 cm3, 43 kW (59 hp) at 9200 rpm, 44 Nm at 7200 rpm, kick starter.

Landing gear:
Double loop frame made of tubular steel, telescopic fork, Moncross suspension strut, cast wheels, 90/90 H 18 and 110/80 H 18 tires.

Measurements and weight:
Wheelbase 1385 millimeters, tank capacity 20 liters, weight with a full tank 170 kilograms.

Price (1983): 5,838 marks (2,985 euros)

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