Motorcycle Repair: vibration in 1983 XJ900RK Seca, engine vibration, wheel balance

Question
I am wondering what could cause vibration in mid RPM'S.  The bike has 22,800 miles.  Could the oil be too thin?  Does it need something tightened in the engine?

Answer
Hi Justin,

Use an oil weight recommended by Yamaha.

Any rotating parts may cause vibration. Engine vibration dosen't mean something has become loose. The frequency at which the engine is rotating, engine design, or frame design may contribute to the vibration.

You can check wheel balance and tire condition. Both can cause vibration. Not much can be done for engine vibration.

Respectfully,
Mark Shively