Need help with GX160 clone

[Texan4Life]

Well I'm stumped. Its a JF168 (gx160) 5.5hp on a HF 2400w generator.

Recently ran it for 50 hrs non stop and it was a champ... until it died. I have about 100hrs on the unit and it got a fuel filter at about 15 or 20hrs.

So I go out thinking [censored]. check it over everything seems good. so i recrank it and it fires up and runs like normal. 4 hrs later i notice it is having trouble with loads and lacking power.

things I have done so far:

The gas is fresh.

Cleaned and regapped spark plug

Air filter is clean as a whistle

cleaned main jet and nozzle

blew and poked out as many passage ways as I could find. Though there are some tiny holes by the throttle plate that I could not poke out because I couldnt find a small enough wire. I was using welding tip cleaners.

adjusted the valves.

It still starts with one lazy pull but it just boggs with lack of power (even with no load)

Any ideas?

Some pics for your enjoyment:

These were the group of holes I was unable to clean (the 4 grouped together to the right of the throttle plate):

 

[Panzerman]

Check the hole at the bottom of the jet, you have on your finger, if its like a Briggs carb. It sucks the gas up thru the bottom. the holes on the side are a distraction. the real fuel feed is on the end of the get. Its like a whistle. They clog up easily, because they take the fuel off the bottom of the bowl.

 

[JTK]

I see you cleaned & re-gaped the plug, but does it have a no-name plug on it? May wanna try an NGK or the likes.

Joel

 

[boraticus]

Get a cheap tie wrap for garbage bags and strip the paper/plastic off of it. The wire inside is perfect for cleaning carbs. Clean those small holes. Run the wire into every orifice you find. Rinse with WD-40 afterward then blow out with compressed air if you have it.

Make sure your governor is connected and working properly. It controls engine rpm to match the load on the engine.

 

[Errtt]

Originally Posted By: JTK
I see you cleaned & re-gaped the plug, but does it have a no-name plug on it? May wanna try an NGK or the likes.

Joel

+1 Get a NGK in there and get rid of the China plug. Don't save it for anything, unless you need it for a fishing weight.

 

[The motor guy]

is the engine made in china or japan? The carb says designed in japan on it.

 

[Chris142]

Replace the plug.

 

[RF Overlord]

Originally Posted By: motor_oil_madman
The carb says designed in japan on it.
"Designed" in Japan..."Counterfeited" in China

 

[lexus114]

at least yours starts on the first pull. Mine ( on my pressure washer) is a bear. i wish i could find an electric start kit for it.

 

[Hootbro]

Originally Posted By: RF Overlord
Originally Posted By: motor_oil_madman
The carb says designed in japan on it.
"Designed" in Japan..."Counterfeited" in China


Counterfeited or copied? There is a difference. For all the smack talked about the Chinese Honda clones, people forget that patents have long expired for that engine and anything is fair game to be copied.

 

[yeehaw1960]

Will the plastic piece on top the carb (under the plastic idle screw) come out? On a Honda carb, there is a screw there that is a low idle jet or something that sometimes gets clogged. I'm very curious what is under that plastic piece. Designed in Japan, made with little or no pride in China!

 

[FusilliJerry82]

Is it a good enough clone that you could replace the carb with a legit Honda part?

 

[Texan4Life]

I went through the carb again this time pulled that piece out (pilot jet). After unscrewing the idle screw you simply pop it up and out. The screw is plastic, but the end has a brass insert.

Cleaned it and cleaned the super tiny holes next to the throttle plate.

The only thing left is the break away (learned the hard way) pilot screw. the screw head is designed to break off and the threads have loctite to prevent removal or adjustment.

I want to choke the smart @ss engineer that thought that was a good idea.

And replaced the plug with a new NGK BPR6ES.

Still the same. I did notice however that the intake (I ran it without the air filer this time) puffs air!

whats up with that?

 

[JimPghPA]

This is a post I made on another thread about using an un-lit propane torch to find out if a carb is lean or rich.

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Regarding using an un-lit propane torch to check the fuel mixture.

First, when you are doing this you must disable any governor.

On a X Y graph, Draw fuel lean or rich on the bottom X line(so very lean is 0 and very rich is far to the right (a high value on X axis)), and draw RPMs on the vertical Y line so very low RPMs are near 0 and very high RPMs are high on the Y axis. Visualize, or draw a curve shaped like a mountain with the Y peak about half way down the X axis.

You will require some means to measure the RPMs of the engine. Some simply use there ear (hearing protection is a real good idea, you are going to be running the engine for a while, and you will be near it).

You can use the propane method to set idle and high end on the carburetor. Set the throttle to the end of the scale you will be working with (idle for idle, high RPMs for main adjust), and leave it at that setting while you are using the propane to test lean or rich, and if adjusting the carburetor, and then re-testing with propane, until you get it to where you are satisfied with the setting.

There are some sites on the internet that give information on how to do this. One recommends that in order to be consistent, you first light the torch, and adjust the flame to about one inch. Then you leave gas valve set for that level of flame and extinguish the flame (usually by placing the tip against the ground for a brief time).

To find out if your engine is running lean or rich, you simply place the un-lit torch tip with the gas coming out at the rate that would make a one inch flame (if it were lit, but it is not lit) near the air intake for the air filter, so that the gas is sucked in the air cleaner along with the air going in while the engine (fully warmed up) is running.

When you do that you have substituted some gas (fuel) for some of the air the engine would normally be getting, and as a result you have increased the fuel mixture temporarily. What is nice about doing it this way is that you have not had to adjust anything on the carburetor to do this. The RPMs will change, either increase, or decrease. If they increase, then the engine was running lean and your engine is running on the left side of the peak of the mountain curve.

If the RPMs decrease when you add the propane, then the engine was running rich and it is on the right side of the mountain curve.

The RPMs of the engine will follow the curve of the mountain. If you start out on the lean side (if you engine is set lean), and increase the fuel in the mix(by adding propane in place of air), the RPMs will increase with an increase in fuel. If you are on the lean side, the increase in RPMs will continue as you add more propane, until you reach a peak. After the peak, if you increase the fuel, the RPMs will fall off.

Ideally you want the engine to be just a very slight amount on the lean side of the peak. It would be nice if the RPMs would increase about 20 or so RPMs as you begin to add some propane, and if you add more propane (get the un-lit torch tip closer to the air intake), the RPMs would stop increasing (be at the peak in the mountain curve), and with even more propane the RPMs would drop (because the engine is now rich in fuel).

There are other examples of how to use a propane torch to check or set the fuel mixture of a carburetor on some sites on the internet. You could google it and read them if you require more information on how to do this.

----------------------------------------------------------------

BTW, you should NEVER excede 3600 RPMs, as anything above that can and probably will damage your engine.

 

[Texan4Life]

The carburetor settings have not been changed. The governor linkage/throttle screw stays on the engine.

I have to say it seems to be running worse. It will only stay running if the choke it on.

ran it without the muffler to rule that out. no change.

I'm thinking something with the auto decompression is wrong. I also read a report of someone with a genuine honda gx160 having the same problems and it turned out his camshaft was worn out. Speculation was it wasn't hardened properly because the engine had little use.

I would just hate to buy a new carb and have it be something else.

 

[JimPghPA]

Use the wire from a tie wrap from a bag of bread, and or get a can of carb cleaner from an auto parts store to clean out the small holes.

Either get a new gasket for the green gasket you damaged, or at least use something to form a seal, silicon or some permatex. If the seal after the carb has ANY air leak it will lean out the air to fuel mix big time.

An un-lit proplane torch will show you if the air fuel mix is lean. If it is, the question could be why? A damaged gasket after the carb could be one reason the engine would be lean.

 

[Texan4Life]

Thanks for the advise so far guys. I finally did find a wire small enough to get those small holes. and the green gasket it in good shape.

I decided to dig in so I wanted to check and make sure the auto-decompression on the camshaft was working properly.

The genhead and side cover are shared and casted as one. turns out they use a tapered shaft so it doesn't have a key. I read a tip about using the through bolt to help separate the two to prevent damage to the genhead.

I can post pics how to do this if anyone is interested.

And you end up with this:

When taking the cover off watch to make sure the camshaft doesn't try and come with the cover like mine did. Lucky for me this chonda has the timing marks on the cam and crank. I have read that some do not:

Here is a short tube showing how it works:
http://www.youtube.com/watch?v=3jHAfvgw32I

 

[dakota99]

Holy smokes finally some internal pictures of chonda! I've been wanting some for a long time, thanks. I was especially curious as to how the all in one genhead and side cover piece looked inside.

Cool stuff. Looks like it's made pretty good too.

 

[Propflux01]

Sure looks like a steep ramp on that cam!

 

[boraticus]

If you suspect the compression release mechanism, can it be removed or disabled?