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.

  • Yamaha R5 350 print ad
    The Yamaha R5 350 Twin.
    Photo courtesy of Yamaha
  • right profile of Honda CB350, and alternative to Yamaha R5 350
    The Honda CB350 was one of the most popular motorcycles of the late 60s and early 70s.
    Photo by Motorcycle Classics staff
  • bridgestone 350 gtr
    Bridgestone is primarily known for making tires, but their Bridgestone 350 GTR was a quality bike.
    Photo by Motorcycle Classics staff

  • Yamaha R5 350 print ad
  • right profile of Honda CB350, and alternative to Yamaha R5 350
  • bridgestone 350 gtr

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.

5/10/2020 10:23:56 PM

I had a '71 with K&Ns, chambers, and I added car coils. The shocks weren't the best, but it handled well. The car coils allowed .060" plug gaps, 700 rpm idle, better mileage and long plug life, and zero fouling.

3/12/2020 7:23:30 PM

Hey "Ringding!" We were talking "box stock R-5" vs. "box stock.CB-350"....not a stock CB-350 vs an R-5 with modified cylinders and porting. Shoot... there was one R-5 in the first AAMRR endurance race that I entered with my CB-500F that was as fast (actually a bit faster) than the CB-500F, but it was disqualified as it had TR-3 road racer cylinders on it (by the same token a CB-350 was disqualified due to having a Yoshimura cam, pistons, etc. in it). So let's not compare "apples" to "oranges." And I can well believe that you would characterize a CB-350 as "sorry"....I did too...until, I actually raced a box stock" R-5 against more than a couple of them. As I said in my post … the R-5 always sounded and felt just simply wasn't as fast as it sounded or felt. Also as I noted, the R-5 was a "Sow's Ear" until Yamaha turned it into a "Silk Purse"...the RD-350...which still had handling issues, particularly with the stock foot peg brackets. And btw...while West Coast racing organizations (AFM. etc) apparently allowed engine modifications in their "Production" race classes, AAMRR and ERA/WERA on the East Coast did least not officially.

7/14/2018 10:30:46 AM

When I rode my 1971 R5- my nerves were made of steel, and so were my tires ! Ok that’s a borrowed quote, not word for word, but I did build up a fast R5 and never touched the brakes or factory rubber -and this was in 1979. But what I did do was hand over my cylinders to a racing two stroke go-cart shop where the next size pistons were fitted and ports opened up, brought the crank assembly to a drag shop known for killer KZ1000 bikes and they checked the rod bearings and tack welded the press fit joints... I hit the 105 mph mark (actual top speed rating) no problem after that and yes I have ridden a sorry CB 350 and you can have it! As for being faster than bigger bikes, yes I was, admittedly they might not have know I was going to race them!

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