I've been rebuilding a JD 314 powered with a rebored Kohler K321 in my spare time for the past year. I've got everything back together and wired up and lucky for me - she runs again! When I get it fired up at low idle all is well and it idles around 2000 RPM. The problem that I'm having is that as soon as I increase the throttle so that it is barely open, the engine surges past max RPMs up to 4200 RPM (manual states that max should be 3600 RPM). Needless to say, I do not run it long at this level...only long enough to get the reading after making adjustments.
I've tried to follow the manual and adjust the governor and my carb jets based on suggested troubleshooting with no results. Currently, the throttle linkage is set so that the governor reads the least amount of sensitivity (pin hole furthest from shaft). Not sure where I left off with my carb jets, but being that it was an issue before I started making adjustments, I do not think they're the issue and they should be pretty close to manual spec. My line of thinking right now is that it is the governor...
It is a centrifugal governor, which has a little arm that sticks off of the shaft inside the block. The little arm is supposed to rest against the end of the governor gear, so that as RPMs increase, the governor gear forces outward and pushes on the arm, which should keep the throttle and engine speed in check.
Since it is revving so quickly, I'm worried that when I reassembled the engine that I may have put the governor shaft in upside down, so that the little arm is effectively doing nothing. Before I spend the better part of a day ripping the thing back apart to check and then putting it back together I wanted to see if this seemed like a likely issue, or if anybody had any other suggestions.