F650 Counter Balance (c/b) Seal Failure FAQ

compiled & edited by Kristian #562
By Flash #412, Elroy#825, John Douglas (UK) & Stephen (Oz), 21/11/01
Thanks to Richard #230, Hombre Sin Nombre
Please read the Disclaimer before attempting any work in this FAQ.
Last Updated: 21 April 2006

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This FAQ concerns a problem which manifests itself in high mileage F650ís and has causedconsiderable concern to those whose bikes have fallen victim to the particular seal failure, not least because the problem has been particularly difficult to identify. Hopefully this will help you or your mechanic quickly resolve what it is that needs repair. This FAQ does not (at present) give a detailed how-to about repairing the problem itself, because it means a pretty severe engine teardown, but it does give pointers on which Parts need replacing.

What is the Counterbalance, or "Compensating" Shaft?

C/B Seal Failure

Typical Symptoms


What you should not do

What you should do before you go to the Mechanic or try and fix it

Luckily, so far this is not a common failure, but it might be worth keeping in mind as our collective kilometres accumulate.