My 1994 GM900S has a front end shake. Some more info:
On the highway:
Doesn't happen all the time; comes and goes, but a weak undercurrent seems to almost always be present.
Gets worse when turning to the left; when pulling the wheel to the right, even slightly, the shake gets much LESS.
When it's really cold out (like six degrees (F) the other morning), it hardly happens at all.
When the shimmy/shake happens, the front end makes a back-and-forth wobble sound. To explain, imagine having a metal shaft with washers welded onto both ends, with a cylindrical collar on the shaft. The collar can move back and forth until it hits the stops on the end (think of a barbell set; shaft with large ends). But the collar ONLY moves back and forth on the X axis, not on the Y or Z axes. Make sense? That's the sound and feel of the front end wobble.
I'm ready to get all new axles and strutts, unless someone reads this and can say "it's 90 percent mostly likely to be ..." Thanks,
-- Don Schenck