Here is part of a longer article by Ric Anderson:
Yamaha XS-650
Years produced: 1970 to 1983
Total production: 500,000 (est.)
Claimed power: 53bhp @ 7,000rpm (at the crankshaft)
Top speed: 105mph
Engine type: 653cc, four-stroke, vertical twin
Weight: 428 pounds wet
If you’ve toured on a Yamaha XS650 for more than a sitcom’s worth of time, you probably fall into one of two groups.
Group one considers the experience as nightmarish as “Joanie Loves Chachi,’’ thanks to the two-cylinder bike’s well-documented tendency to vibrate at highway speed.
The other group’s feelings are perhaps best voiced by Jim Griner, a longtime XS650 owner from Hoopeston, Ill., and founder of the 1,000-member Yamaha 650 Society.
“At the right speeds and in good tune, there’s a cycle of vibration that seems to be very harmonious with the human anatomy,’’ Griner says. “Those of us who are able to tune the engine correctly tend to think of that as the motorcycle’s pulse in a friendly sort of a way.’’
The XS650 has generated a deep fan base for its reliability, adaptability and classic lines.
“They just keep being recycled,’’ Griner says, “and that speaks to the bulletproof nature of them.’’
The engine, with its horizontally split crankcase and chain-driven camshaft, drew positive reviews and helped make the entire package stand out.
It succeeded by solving some of the shortcomings of its English predecessors, including chronic oil seepage and fritzy electronics.
“It doesn’t leak, it doesn’t break, it doesn’t require much attention and it doesn’t cost much,’’ Cycle Guide said. at the heart of the bike’s long production run and enduring following is its rock-solid engine.
Thanks to a chain-driven cam as opposed to long pushrods, the pistons and valves can work at 7,000rpm with little fear of the engine self-destructing. The roller bearings for the cam- and crankshafts have proven to be remarkably durable.
“The 650 was designed before computers, so everything in it was built overly strong,’’ Griner says. “I think in all of the years I’ve been around the thing, I’ve only heard of one person who spun a bearing in the bottom end. Overall, there just aren’t that many things that go wrong with it.’’
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