The Yamaha R5 350 Twin

In an era when small-bore engines were still fairly common, the Yamaha R5 350 Twin was in many respects the company's crown jewel.


| November/December 2009



Yamaha R5 350 print ad

The Yamaha R5 350 Twin.

Photo courtesy of Yamaha

Yamaha R5 350 Twin
Years produced: 1970-1972
Claimed power: 36hp @ 7,000rpm
Top speed: 91mph (period test)
Engine type: 347cc air-cooled 2-stroke parallel twin
Transmission: 5-speed
Weight: 322lb (dry)
MPG: 30-40
Price then: $779 (1971)
Price now: $1,000-$2,500

Try to find a 350cc or smaller streetbike today like the Yamaha R5 350 Twin and you’ll discover the pickin’s are slim. Honda has only one, the 234cc Nighthawk; Kawasaki two, the 124cc Eliminator 125 and the 249cc Ninja 250R; Suzuki two, the 249cc retro-style TU250X and cruiser-styled GZ250. And Yamaha? Ignoring the 249cc V-twin cruiser in its new Star Motorcycle line, you won’t find a single 350cc or smaller machine carrying the Tuning Fork logo.

The 21-inchers

That wasn’t the case back in the early 1970s, when small-bore bikes still ruled and the so-called 21-inchers (350cc = 21.35ci, hence the 21-inchers moniker) were among the hottest contenders for the motorcyclist’s dollar. Besides a smorgasbord of small-bore bikes from Italy, England and Germany, there was a full plate of small bikes available from Japan, including Yamaha.

By 1970, Yamaha had emerged as one of the leading Japanese motorcycle makers, behind Honda but ahead of Kawasaki and Suzuki. While Honda continued to embrace the 4-stroke ideal, Yamaha, like its other Rising Sun rivals, was still putting most of its faith in 2-stroke technology.

Despite the introduction of its first-ever 4-stroke, the 650cc parallel twin Yamaha XS-1, Yamaha wasn’t about to walk away from its 2-stroke twins and singles, which had brought Yamaha success in the consumer marketplace and on the track, and Yamaha knew there was still a lot of performance — and dollars — to wring out of its smaller bikes.

Yamaha had introduced its first “big” 2-stroke, the 305cc Big Bear, in 1966. That was followed a year later with the all new YR1 Grand Prix, whose short-stroke 348cc twin benefited heavily from lessons learned on the track, and finally, in 1970, the YR5, or the Yamaha R5 350 as it was known in the states.

jdunne
11/10/2017 4:26:41 PM

What a crock! I owned and road a 1971 R-5B (orange & white gas tank) during 1972-72, putting about 20K miles on it. While Cycle magazine had declared it the "winner" in a 1970 350cc comparison test and Yamaha claimed "race-bred" power and handling, I very quickly found out that a Honda CB-350 would outrun it, particularly if you didn't put a new set of plugs in the R-5 immediately before the run. At first I was very frustrated and bewildered about this situation, but later I came across the Cycle World tests of both bikes and learned that their CB-350 had been almost 1/2 second quicker in the 1/4 mile than the R-5 (15.1 vs 15.5 sec.). I also got the chance to ride several CB-350s and found that they were easier to get off the line than the R-5 and covered ground much faster than their engine note would otherwise indicate (the R-5 always sounded fast...it just simply wasn't as fast as it sounded). The idea that a stock R-5 would run as fast as a bike "twice its size" (as Mr. Backus presents) is quite simply preposterous and mythical. While an R-5 could, possibly, give a single-carb, 4-spd Triumph or BSA 500 a hard time, it would simply be an appetizer for a CB-450 with a 5-spd box. As well, the R-5's tranny ratios didn't help as there were significant gaps between 1st and 2nd and 4th and 5th gears. One had to wind 1st gear pretty tight to avoid bogging when you shifted into 2nd (despite the R-5's relatively wide power band for a piston-port engine) and you could get caught in city traffic situations "between gears" (1st being too low, while 2nd was a bit too high). As well, 4th was useless as a passing gear above 60-65 mph. The handling was also less than stellar, being that the R-5 had too little weight on the front wheel (at least with the stock handlebars), a short wheelbase and quick steering...can you spell t-w-i-t-c-h-y? While the light front-end enabled you to pull easy (and many times unintentional) wheelies (reinforcing the illusion of speed and power), it also made the steering and handling rather dicey coming out of corners, particularly on a road with slow, tight curves (just the kind of road where you might think that you could catch that CB-450 or Triumph Daytona 500 that had just blown you away on acceleration). And like most 2-strokes of the period, points and plug life were also issues...aggravated by the fact that Yamaha didn't have any check-valves in their Autolube system (Bridgestone, Kawasaki and Suzuki all had them) which contributed to over-oiling, particularly at idle. I eventually gave the R-5 to my Dad and got a left-over '72 Honda CB-500 Four, riding and racing it with AAMRR and WERA for 3 years and 30k street miles and being much happier. I will give Yamaha one thing, though, "The Sow's Ear to Silk Purse" award for converting the R-5 into the 1973 RD-350...which corrected almost all of the R-5's shortcomings (except for plug fouling)....but was really no quicker than a 1969 Kawasaki A-7 350. I will forever wish that I had bit the bullet and bought a Bridgestone 350 GTR instead of the R-5...6-spds (no gaps), rotary valves (quicker and a wider power band), rubber-mounted engine (no vibration), more weight on the front wheel and a much better highway bike for running home from college on weekends.


ijfluker
9/19/2014 1:35:12 PM

I can't agree that the R5 Yamaha was fine handling. I borrowed my brother's for a SMR (sunday morning ride) and experienced a serious "tank slapper". My CB 350 on the same stretch of road was much less frightening.






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