JD 314 Rebuild - Throttle accelerates immediately beyond max after idle RPM
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Thread: JD 314 Rebuild - Throttle accelerates immediately beyond max after idle RPM

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    JD 314 Rebuild - Throttle accelerates immediately beyond max after idle RPM

    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.

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    Sure sounds like the governor is not set correctly. Maybe you turned the rod the wrong way before you tightened the arm on it or something like that.
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    If you grasp the throttle plate lever, can you adjust the engine speed in a linear fashion?

    FYI, I had a 314 with the same engine that I purchased used. Idle was very rough. I found the throttle shaft holes, in the main body, had elongated from wear, allowing excessive amount of air to leak around the shaft. I found a kit with two bushings and a new shaft that resolved the problem.
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    I can't really help you with the governor on your engine as I know nothing about it. But just as a coincidence, I just got through taking apart a old Briggs L head opposed twin to replace gaskets and seals. When I got to where I needed to hook up the linkage and set the governor shaft I had the same trouble. It would not idle, just wanted to run fast. Every last video I could find on youtube had you turning the governor shaft clockwise to set. I could not find a video on just the engine I had. One guy stated that it didn't matter what engine you had, set it clockwise. Well, I found mine is opposite. It has to be set counter clockwise because of the location of the governor inside. Runs perfect now.
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    Unfortunately, the governor is not operating correctly, but make sure before you tear it apart that you don't have something simple hooked incorrectly, like a spring in the wrong position or missing, or something in the linkage. There is nothing else on your engine which can cause the symptoms you are describing from idle to RED LINE........but the governor. Fuel jets can't do this.......but incorrectly connected linkage can.

    The linkage is often where this is done incorrectly. This is one reason why I will often take pictures before disassembly as over time, we forget what hooked where and how and with you working on this over a year, its even easier to see how something could have been overlooked.

    Start with the simple on the governor FIRST, and once you are POSITIVE you have the linkage right and springs pulling the correct direction in the correct position, then removing the shroud is the next option.

    I would bet you have a linkage error for it to be so dramatic in RPMS in such a short movement of the throttle.............One thing for sure, it won't live long at 4,200 RPMS.........

    Maybe another member with the same machine can post photos of their detailed throttle linkage hook ups for you to use to verify before you get too far...

    Did you rebuild the carb or get inside of it during this project?
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    If you grasp the throttle plate lever, can you adjust the engine speed in a linear fashion?

    They seem tight. You can adjust engine speed using the linkage or lever without any additional play. That being said, I'm guessing they're not air tight and I can definitely try something to seal them temporarily to see if it helps, then maybe look for the bushing kit as a more permanent fix.

    Sure sounds like the governor is not set correctly. Maybe you turned the rod the wrong way before you tightened the arm on it or something like that.

    &&

    I can't really help you with the governor on your engine as I know nothing about it. But just as a coincidence, I just got through taking apart a old Briggs L head opposed twin to replace gaskets and seals. When I got to where I needed to hook up the linkage and set the governor shaft I had the same trouble. It would not idle, just wanted to run fast. Every last video I could find on youtube had you turning the governor shaft clockwise to set. I could not find a video on just the engine I had. One guy stated that it didn't matter what engine you had, set it clockwise. Well, I found mine is opposite. It has to be set counter clockwise because of the location of the governor inside. Runs perfect now.


    The manual states to twist the governor shaft fully counter clockwise, then pull the governor arm all the way away from the caburetor (also in counter clockwise direction) - then tighten lock not. The manual is a little confusing in this area as some instructions seem to be for a different model year of the K321 and it is not clearly labeled. From what I am hearing, the most likely issue is that i've got the rod in 'upside down' - so that the little arm is pointing toward the bottom of the block instead of the top where the governor gear is. The range of motion inside the block will not allow you to twist it fully between 'up' and 'down'...you would have to remove it, flip it, then reinsert it.

    Sounds like I'll be ripping it down then

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    Thanks for the reply SulleyBear. I actually had taken some pictures of the linkages back when I was disassembling so I believe they are correct.

    I did pull the motor tonight, which actually wasn't too bad to do an inspection since I only had to get at the oil pan and did not have to remove the shrouds/carb/cam/other components to get a look. What I discovered was that the shaft was inserted the right way with the little arm pointing toward the governor gear...however there is a spacer, probably about 3/4" or so, that fits over the governor shaft and keeps the arm squarely over the governor gear pin. My best guess is that this spacer is roaming free somewhere on the floor of my garage, so the shaft is able to work its way out during the vibration of the engine running, which then lets the governor run wild.

    So after I get a new spacer the real fun will begin. I'm not sure if I'll be able to remove the governor shaft without also removing the cam and most of the other components. If I can, then it'll be a pretty easy swap. If I can't then the job will be significantly more difficult, which means I'll probably give it the cold shoulder for month or so.
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    You mentioned at idle it idles at 2000 rpm. That alone would seem extremely high to start off with. I'd guess it should be in the 600rpm range. Could be thats where your problem is starting off with.
    Just thinking out loud.

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    Quote Originally Posted by Toughsox View Post
    You mentioned at idle it idles at 2000 rpm. That alone would seem extremely high to start off with. I'd guess it should be in the 600rpm range. Could be thats where your problem is starting off with.
    Just thinking out loud.
    1800 is spec. They will idle at 600, but that lacks sufficient cooling if you were running at wot and try to idle it.

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    Quote Originally Posted by rydplrs View Post
    1800 is spec. They will idle at 600, but that lacks sufficient cooling if you were running at wot and try to idle it.
    I don't know what kind of oil pump that engine uses, but I've heard that a splash type won't deliver enough oil to the upper part of the engine if you set the idle too slow.
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