Rotax viabration.

Here is site I uploaded from:
http://www.rotaxservice.com/rotax_tips/rotax_vibration.htm
Note Powerpoint viewer is required, it would not open with the version of Powerpoint I have. Powerpoint viewer is free.

I also heard from a A+P who worked on a lot of 912 powered Katanas, he said that the washer at the end of the crankshaft holding on the gearbox drive gear if not centered would cause viabration.

Here a guy says that the crankshaft nut if not properly torqued can cause viabration and other problems:
From: "Malcolm Ferguson" <malannx@bigpond.com>
Date: Sun, August 8, 2010 8:15 am
To: rotaxengines-list@matronics.com
If anyone pulls gearbox off, a must do is to check the torque on the crankshaft
gear. Requires a deep 41mm socket or 1and 5/8". Rotax mechanic showed me a
crankshaft that had the splines trashed by a loose gear. Will produce vibrations you
can't cure otherwise. Even gave me a new belville washer in anticipation I would
find mine loose - I did. He had seen enough of them loose that a torque check was
mandatory if the gearbox was off. If below torque the nut must come off and a
careful check of the striations on the bellville washer will show if there had been
any movement. If any shine on the striations a new washer is a must(and loctite).
When swinging on the end of the torque wrench, I remember thinking about the "agony"
the little crankshaft locking pin was going through.
Malcolm Ferguson