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Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving high

Hey Everyone,

I got a mower given to me by my father in law, it is in good condition other than the fact that it is revving far too high. It starts fine, the throttle is not sticking.

He tells me it is the "turbo" winding up and getting stuck. According to him there is a small weight on a spring or something similar that should level itself out once the mower starts. You can move the linkage attached to this assembly from the outside and the rev's do come down to a reasonable level.

So, my question is can anyone confirm if this sounds like the issue and what this assembly/function is actually called as well as any advice on how I might go about repairing it. I have a fair amount of technical/mechanical experience so I am planning to start at the top and work my way down until I find the part sticking. Not finding too much repair material online though, so would really appreciate any advice/pointers/information you may have regarding this.

Thanks in advance!

Re: Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving

Start by resetting the governor this way. Push the governor arm forward so that the throttle plate is wide open. Loosen the nut holding the governor arm to the governor shaft. Rotate the governor shaft in the same direction as you moved the governor until it stops. Hold it there while tightening the nut. An assistant will be of great help if you have one around.

Re: Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving

Thanks rivets, I'll give that a shot. Glad I asked and avoided doing much more work than necessary.

Re: Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving

djwcmurphy said:

Thanks rivets, I'll give that a shot. Glad I asked and avoided doing much more work than necessary.

Click to expand...

Hi Rivets,

I tried what you said and am having an isssue.

Please take a look at these pictures. Are these the governor arm and shaft you were referring to? The nut comes off, I can push the arm down where the arrow is pointing. The shaft only turns a very minimal amount though. From the perspective of the picture it can turn to the left not even a quarter turn, MAYBE an eighth of a turn. It is very minimal movement. Should it be able to move more than that?

Even so, I moved it as much as it would and tightened the nut back down, but unfortunately it did not improve the situation at all. Also, please clarify, when tightening the nut back down should I be holding the arm down or let it back to it's resting position?

Any more advice?

Re: Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving

I've contacted Robert@honda asking him to better explain how to adjust the governor. I can't find any good pics to give you an explanation you can understand. He also may have a different cause of your problem. We'll see what he has to say before proceeding.

Re: Craftsman 21" Walk Behind Mulcher mower / Honda 5.5 HP engine - Engine revving

Let's get some basics first.

I'll bet this is a Honda GCV160 engine. But, to be sure, can you share the serial number off the side of the engine block? It will be in the format GXXXX-1234567.

Does the mower have a remote throttle control on the handlebar? Or, is the engine a "fixed-throttle" type that runs wide open all the time?

To properly set the engine speed correctly and safely, you really, REALLY need a tachometer. There are dozens available; most work by picking up a signal from the spark plug wire.

Here are the two most common procedures, depending on if the engine has a throttle control plate or not, but both shown are for engines WITHOUT a remote throttle control: