BIKE GOES DEAD ON HIGHWAY

Patton wrote:

When hand rotating the crankshaft for whatever purpose, always use the 17mm nut, and never use head of the smaller 13mm bolt screwed into end of the crankshaft.

The larger 17mm nut is designed for this purpose.

Using the smaller bolt head risks snapping the head off the bolt leaving threaded portion tightly screwed into end of crankshaft.

Good Fortune!

[Click on image to enlarge view.]

Good tip, now that you mentioned I do remember there being "two" accessable nuts on the end of the crank. I must have used a 17mm box wrench on my GPz when I did my valve adj check..