Official Honda engine repair thread

[Andrew Bandarovich 39]

Thought we should have one to have everything in one place. Moderator, please make this a sticky.

I ll start: I have Honda GX390 with a problem that goes like this - I turn choke lever to the left, start it, raise rpm to the max with speed lever and when I return choke lever all the way to the right the engine starts running rough (surging up and down). I have to back out choke 1/4 of the way to keep engine running smooth and not surge. Honda shop says the needle in the carb needs to be adjusted to enrich it. But it would take a week for them to get to it. I can't leave pressure washer there for a week. Anyone has experience with GX390 carbs and knows how to enrich the mix?

[Russ Johnson 141]

Modern carburetors no longer have a mixture screw...EPA rules. Sounds like you've got some crud in the main jet. Take the bolt out of the bottom of the bowl (shut the gas off first). The jet is located straight up in the tube the bolt came out of. Welding tip cleaners work well for reaming the gunk out, but be careful, you don't want to remove any brass from the jet. That will oversize it, and it will run rich.

One other remote possibility is a cracked insulator. That;s the black piece between the carb and the cylinder head. While the engine is running rough, spray some carburetor cleaner in that area. If there's a crack, the engine will pick up carb cleaner instead of air, and smooth out.

[Andrew Bandarovich 39]

Thank you Russ.

Will try this out and report back.

[Chemical Doctor 15]

One other thing to check is the governor spring. Make sure it is connected on both ends.

[mick m 19]

Had the same problem a few years ago. next to the ''thick'' governor spring there is a really fine wire spring called a steady spring, check that out as mine had snapped & caused the same problem.

[Alexy 85]

Modern carburetors no longer have a mixture screw...EPA rules. Sounds like you've got some crud in the main jet. Take the bolt out of the bottom of the bowl (shut the gas off first). The jet is located straight up in the tube the bolt came out of. Welding tip cleaners work well for reaming the gunk out, but be careful, you don't want to remove any brass from the jet. That will oversize it, and it will run rich.

One other remote possibility is a cracked insulator. That;s the black piece between the carb and the cylinder head. While the engine is running rough, spray some carburetor cleaner in that area. If there's a crack, the engine will pick up carb cleaner instead of air, and smooth out.

What he said... Shut the fuel off take a 10mm socket and drop the bowl, protecting the rubber gasket at the top. Clean the bowl out and rather than ream it out take carb cleaner and shoot it straight up the jet, then tun the fuel on and let it flow for a minute. It loosens the junk in the jet and the high flow because the bowl is removed allows the garbage in the line to flow straight out as well. One other thing to do is take the 3 bolts off the tank take it off and clean the screen at the bottom of it also flush all the rust out of the tank. Take a few bolts and screws and put them in the tank and shake the hell out of it to knock all the garbage off the inside of the tank then open it up flush it out and let it dry out then reassemble.

[Guy B 70]

I got a 24hp Honda doing the same thing. Lots of how to videos on youtube for honda, but I would start with Russ's advice first.

[Andrew Bandarovich 39]

Governor was replaced two weeks ago, the spring is there and is connected at both ends. I had this issue before governor replacement.

[Andrew Bandarovich 39]

What he said... Shut the fuel off take a 10mm socket and drop the bowl, protecting the rubber gasket at the top. Clean the bowl out and rather than ream it out take carb cleaner and shoot it straight up the jet, then tun the fuel on and let it flow for a minute. It loosens the junk in the jet and the high flow because the bowl is removed allows the garbage in the line to flow straight out as well. One other thing to do is take the 3 bolts off the tank take it off and clean the screen at the bottom of it also flush all the rust out of the tank. Take a few bolts and screws and put them in the tank and shake the hell out of it to knock all the garbage off the inside of the tank then open it up flush it out and let it dry out then reassemble.

Thank you Alexy.

I am actually planning to remove the gas tank and mount bigger one above it on the frame.

[Andrew Bandarovich 39]

Cleaned out carburator and it is running good now. Thank you everyone.

[Alexy 85]

Bill is in the mail ;-)

Glad it was a simple fix...

[Scott Stone 604]

I just turn mine over to the in house mechanic. I love having a mechanic on staff.

[Jim Gamble 20]

I just turn mine over to the in house mechanic. I love having a mechanic on staff.

I know what you mean Scott, I am glad you finally did that. I remember how you was concerned about the expenses of that.

As you know, we have had a mechanic onsite when we clean our Garages for the last 7+ years or more.

He has saved us thousands of dollars in lost hours on the Job site. I remember 25 years ago, when I had equipment fail and then had to go home only to drive an hour or so to the shop to have someone fix it the next day, that is, if the shop was not too busy and they could rush us into their schedule.

I am happy for you that you got that done! Way to go Scott !!!

[spbutton 14]

Condescending... Much?