Monday, August 11, 2008

well kiss my ass yankees

The Yamaha 650cc SOHC vertical twin was produced from around 1969 to 1983. It vibrates and doesn't have blinding speed, but is brutally reliable and a genuine hoot to ride. The original 4-stroke motor design is rooted in the Toyota 2000 GT engine which was designed by Yamaha. Comparisons to the classic British vertical twins, Triumph, BSA, Norton, et al, are not without merit. Early models were notoriously poor handlers, but had excellent engines. Around 1975, Percy Tait, renowned Triumph motorcycle engineer and racer, tweaked the Yamaha 650 frame for his own racing team greatly improving the handling characteristics. Yamaha implemented his frame modifications and made a good engine even better.

Ironically, today the Yamaha XS650 is one of the most popular bikes in the UK and Europe, examples in good condition fetch well over $2,000US. The engine features 3 caged roller bearings on the crankshaft, 4 on the single overhead cam, and needle bearings on the rocker arms. An electric starter and front disc brake were added in the 1972 XS2 and an electronic ignition system in the 1980 G model. Through out the 650s production life improvements were implemented and the last several models are excellent bikes.

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