Honda GX390 Governor Issues

[Skywatcher]

Greetings All

Here's an interesting one for you. Customer bought a new post pounder with a Honda GX390 engine and put it to use. After a couple of years and about 100 hours of engine time, the engine started racing uncontrollably so he brought it to me. Ran all the usual checks and adjustments to no avail. After splitting the crankcase open, found that the end of the governor slider had worn right off. Talked to retailer who said the engine warranty had expired about 2 months earlier. Installed a new governor and slider, figured problem was solved so sent unit home, this was 2 years ago.

The machine came back a week ago with the exact same problem, 2 years of use and about 100 hours of engine time. Ran all the checks again, split the crankcase open, same thing, end had worn right off the governor slider. However, this time there was enough wear on the governor shaft internal arm that I could see the slider had been rubbing on the top edge of the arm as opposed to somewhere on the flat where it's supposed to. Ordered new governor shaft from nearest Honda dealer and compared the two. New shaft fractionally longer with a slightly different angle of bend. When installing the new governor shaft, installed a thrust washer under the external retainer pin to hold the governor shaft a little higher than it was. Hopefully I won't see this engine again for a long time.

Has anyone else run into this problem with Honda GX series engines? The engine drives a hydraulic pump, so is not subject to any sort of shock loading except the vibration each time a post is struck with the hammer slide.

Make: Honda
Model: GX390
Type: QA2
S/N: GCBCT-1082414

All the best,

Sky

[KE4AVB]

I am assuming you mean the bell crank arm. If so I haven't seen that on a Honda but seen several Briggs over the last 10 years where the bell crank was off center of the pin. Just made the need bend here to align it but these were old engines that I was overhauling. The question is have checked the alignment of the new parts? I know it inside case where you can't eyeball it but should be able use some machinist's blue or red to see the contact points.

I what have seen being reported is the mounting pin on some Briggs v-twin wallowing out the mounting hole in the cylinder block and whole governor assy falling out. Several of my Aussie friends has had that problem. Personally I haven't even seen this one either.

[Skywatcher]

Hi KE4

If the bent part of the governor shaft that the governor slider pushes against is called the bell crank, then yes. I tried bending the bell crank arm to correct the problem, but Honda uses such hard steel that the arm developed a hairline crack after bending it about 4º, so that part was not going back in the engine. If the arm broke off and fell into the inner working of the engine, I'd be on the hook for a new engine and my reputation would go down the toilet.

Hadn't thought of using Prussian Blue or a similar product for checking contact point between governor slider and bell crank, don't even have any in my shop. If the engine comes back in another couple of years, I'll have to do some serious digging, maybe even take it to a Honda shop and discuss the situation with a knowledgeable technician. I might just take the old slider and governor shaft to my nearest Honda dealer and see if the shop techs there have ever seen this situation. All the best,

Sky

[KE4AVB]

Definitely don't want to put back in a crack part. Just makes good judgment call there.

[bgsengine]

Hadn't thought of using Prussian Blue or a similar product for checking contact point between governor slider and bell crank, don't even have any in my shop.
Sky

Use a colored grease, or you can use some artist oil paint - just a dab smeared on bellcrank and then with things partly assembled, you can swing governnor arm back and forth a few times, take it apart and you should be able to see the contact marks made on the bellcrank. (assuming parts are clean, oil-free and dry)