Honda GX270 problem

[Nodroz]

Hello,

Some of might remember this engine from somewhere. It's from my kart I've found on the scrapheap. Apperently people just didn't throw it away for nothing. My engine was leaking oil so I started searching for any leaks then I have discovered a crack in the engine's case.

However, I don't think this is the source of the leak, since it's not wet of oil.

I'll you a little story about what happened, which I think might be useful information to discover the leak.
I saw the engine was leaking, the cilinderhead gasket was worn out. I ordered a new one. When I was opening the OHV cover with that screw in the middle, I broke the screw. The rest got stuck in the case. Since I don't have the tools to get that out and make a new thread, I went to the shop. I've also asked them to replace the cilinderhead gasket, so I don't need to do it anymore.

After more than a week, I called. They repaired the thread and a new screw has been ordered and delivered. They didn't install that gasket yet, because he said he was busy with other engines. I said I'll do it myself, so it'd be easier for both.

So, I opened the cilinderhead and replaced that gasket - everything's fine. When I was mounting the cilinderhead back in the cilinder with those 4 bolts a major problem occured. One of those big screws was ruined. Not the screw itself, but the thread where the screw goes in. I fixed it with a bit of teflon and the screw was back ok.

I started my engine and everything was running fine. The leak between cilinder and cilinderhead was gone and the engine ran fine.
Today I went for a drive, for the first time since the repairs. I only drove like 5 to 10 minutes. When I came back home, I saw some spots of oil on the stones of my terrace. I started to inspect the engine carefully. Suddenly I spot that crack, what I have been talking about earlier. However, I don't think it's the source of the leak. I think the leak is around the rubber fitting of the OHV cover (yes, that thing that has been repaired). Tomorrow I'll clean it up, start the engine and see if there's oil there.

If that's the case, I'll go back to the shop. However, if it's not there, it should come from that crack... which means my engine is broken and almost irrepairable, since I'll need to get a complete new engine case.


I have another question!

During the repair I've ordered a flexible exhaust. I used that for the first time today. I've discovered that the exhaust pipes from the engine and the flexible piece became very black. I was wondering if this means something? Maybe not a good combusting, or running too rich / lean?

Here are few pictures:

I hope there are some people around here who are willing to read this boring text and hopefully come up with some ideas / comments.


Regards,
Nodroz

 

[r_chez_08]

R.E. the OHV cover (known as rocker cover)
They will leak if the gasket is bad or not replaced, or the bolt is not torqued down correctly.

R.E the crack.
If that is actually a crack and causing issues, take the engine off, sand and thoroughly clean the area and hit it with JB weld. If you can get to the inside of the crack, do that as well.

R.E. black exhaust:
Get a new spark plug and go for a few 'high speed' runs. Don't let it idle too long. Then check the plug. Do a few searches for 'Spark plugh charts' or 'plug chop'.

 

[Nodroz]

R.E. the OHV cover (known as rocker cover)
They will leak if the gasket is bad or not replaced, or the bolt is not torqued down correctly.

R.E the crack.
If that is actually a crack and causing issues, take the engine off, sand and thoroughly clean the area and hit it with JB weld. If you can get to the inside of the crack, do that as well.

R.E. black exhaust:
Get a new spark plug and go for a few 'high speed' runs. Don't let it idle too long. Then check the plug. Do a few searches for 'Spark plugh charts' or 'plug chop'.

1. I'll look for that gasket tomorrow.
2. So you're saying that I would be able to weld that crack? Isn't the engine's case aluminium, which I can't weld with my electrodes welding machine.
3. The spark plug is 2 weeks old. I'll get it out and see how it looks like.

Thanks for your answers.

 

[spyder1968]

JB weld is a very tough 2 part epoxy ! should easily fix you right up if you get the area good and clean before applying it ( and maybe rough it up a bit too)
available at any auto parts store.

 

[r_chez_08]

2. So you're saying that I would be able to weld that crack? Isn't the engine's case aluminium, which I can't weld with my electrodes welding machine.

http://jbweld.net/index.php
Two part epoxy which has fine metal particles or something. Dries the colour of cast aluminium.

3. The spark plug is 2 weeks old. I'll get it out and see how it looks like.

Sure, have a look. If it doesn't look right, give it a clean up and try the technique I suggested. Worth a try.

BTW, is English your second language?

 

[OzFab]

http://jbweld.net/index.php
Two part epoxy which has fine metal particles or something. Dries the colour of cast aluminium.

... or see if you can find someone who will TIG weld it for you.

Sure, have a look. If it doesn't look right, give it a clean up and try the technique I suggested. Worth a try.

IMO, it's running a bit rich. If your plug is black this will confirm it; plug should be a tan colour. Replacing the head gasket can affect mixture

BTW, is English your second language?

Where have you been hiding chez, he's from Belgium, as stated in his first ever post

 

[Nodroz]

http://jbweld.net/index.php
Two part epoxy which has fine metal particles or something. Dries the colour of cast aluminium.


Sure, have a look. If it doesn't look right, give it a clean up and try the technique I suggested. Worth a try.

BTW, is English your second language?

Thanks for the link. I'll check that JB weld out. I hope it isn't too expensive, because I don't want to spend much more on this engine.

I'm learning 4 different languages on school.
1. Dutch (My motherlanguage)
2. French (2nd primary language in Belgium)
3. German (3rd primary language in Belgium)
4. And last but not least, English. I learned most of the English from reading English forums and reading English tutorials or manuals of engines.

JB weld is a very tough 2 part epoxy ! should easily fix you right up if you get the area good and clean before applying it ( and maybe rough it up a bit too)
available at any auto parts store.

Will they need to access the inside of that crack?

... or see if you can find someone who will TIG weld it for you.

IMO, it's running a bit rich. If your plug is black this will confirm it; plug should be a tan colour. Replacing the head gasket can affect mixture

Where have you been hiding chez, he's from Belgium, as stated in his first ever post

Thanks for your answers. I'll have a look at the plug in a moment. I think I'll go for the TIG weld, since I know somebody who would be willing to do that for me for a cheap price. Altough, I think I'll need to open up my engine.

UPDATE:
Got the spark plug out and took a picture of it. It's completely black, which means it's running to rich? Right?

On the carb, I only have 2 adjusting screws. One for the idle and one for ... not sure what's it for.

I wonder if there shouldn't be a screw here?

 

[r_chez_08]

Try cleaning off and doing my method. May be a rich idle circuit. If it is rich at higher RPM this would be a nice excuse to get a high flowing performance air filter and adapter. If you don't want to do this, you need a leaner main jet with a thinner hole in the centre.

Where have you been hiding chez, he's from Belgium, as stated in his first ever post

Yeah I know, just wondered where he got his remarkable English skills from. He may have been brought up in an English speaking country or something. Kudos to you, your language skills are bloody good!
If I was that good at french I would be very happy!

BTW Fabroman, how can changing the head gasket affect mixture? Not doubting you, just interested!

 

[Nodroz]

Try cleaning off and doing my method. May be a rich idle circuit. If it is rich at higher RPM this would be a nice excuse to get a high flowing performance air filter and adapter. If you don't want to do this, you need a leaner main jet with a thinner hole in the centre.

Hmm, pretty annoying I've just bought a new airfilter. Not from K&N. Maybe the plug is still black from the previous airfilter. I'll do some more driving and see if the air inlet is better.

Yeah I know, just wondered where he got his remarkable English skills from. He may have been brought up in an English speaking country or something. Kudos to you, your language skills are bloody good!
If I was that good at french I would be very happy!

Thanks a lot! I appriciate it!


Found the oil leak!
When I was taking pictures of the carburator, I saw there was some oil on the ground. It was not under the engine, it was below the wet clutch. It seems that there is some oil leaking through the bearing. Here are some pictures:

I've cleaned the spot where the crack was. I'm not fully sure anymore - What do you guys think? Is this a crack or just a normal fabrication inequality? Here are some pictures.

Regards,
Nodroz

 

[Doc Sprocket]

The "crack" is really starting to look like a casting anomaly, and of no concern. I could be wrong. The only way to tell is a thorough inspection (which I can't do).

As for the bearing- sweet and easy. Just replace the oil seal that is leaking.

For the spark plug- clean it completely. Reinstall it and run the engine at wide open throttle under load. Kill the engine while under load, remove plug, and inspect.

 

[OzFab]

BTW Fabroman, how can changing the head gasket affect mixture? Not doubting you, just interested!

If a head gasket is leaking it effects compression, agreed?

If a damaged or worn head gasket can allow air to be forced out of the cylinder during compression, it's only logical that it can allow air to be sucked in during intake &, therefore, altering the fuel/air mixture.

Yes, it would only be minimal (depending on how bad the head gasket is) but, a minimal change is still a change

 

[OzFab]

Got the spark plug out and took a picture of it. It's completely black, which means it's running to rich? Right?

That's correct

On the carb, I only have 2 adjusting screws. One for the idle and one for ... not sure what's it for.

That big brass screw look like it may be a mixture screw.

I wonder if there shouldn't be a screw here?

Not sure about this one (unfamilar with this carb) Is it open? How deep is it?

 

[Nodroz]

That's correct
Not sure about this one (unfamilar with this carb) Is it open? How deep is it?

It's open and around 1 - 1,5 cm deep. I think it's closed at the bottom though. Altough, I find it it a weird thing. Could somebody check their Honda GX carburetor to see if they have something there?

The "crack" is really starting to look like a casting anomaly, and of no concern. I could be wrong. The only way to tell is a thorough inspection (which I can't do).

As for the bearing- sweet and easy. Just replace the oil seal that is leaking.

For the spark plug- clean it completely. Reinstall it and run the engine at wide open throttle under load. Kill the engine while under load, remove plug, and inspect.

Exactly, this is what I think also. It's not leaking oil or anything else out that "crack" so I assume it's just normal.
I'll check that bearing next week, once my exams are over. I hope it's an easy fix.

I have a "race" planned tomorrow. How'd you clean the spark plug?

 

[r_chez_08]

That doesn't look like a crack, just casting anomaly.
As toystory said, replace the oil seal, should be fine then. Glad it was nice and simple.
Are you on about the black hole? That is the low speed jet. Get a screwdriver under and pop it off. You should be able to see what I am on about.
The brass one is also a low speed adjustment. Stock it should be 2.5 turns out from the seated position. (for the gx160/200 anyway!)

The other screw above the black bit is the idle adjustment.
Let me find you a helpful link in a minute for your engine.
Loads of manuals, carb info, shop specs (torque values etc) and stuff like that. Really useful stuff.
Here you go:
http://cssportal.css-club.net/honda/PowerProducts/TERMS010.aspx
Say your a 'dealer'.

Is the air filter standard or a high flow one?

 

[OzFab]

I have a "race" planned tomorrow. How'd you clean the spark plug?

Wire brush. It's a new plug so it won't be too bad

 

[r_chez_08]

If a head gasket is leaking it effects compression, agreed?

If a damaged or worn head gasket can allow air to be forced out of the cylinder during compression, it's only logical that it can allow air to be sucked in during intake &, therefore, altering the fuel/air mixture.

Yes, it would only be minimal (depending on how bad the head gasket is) but, a minimal change is still a change

OK, I thought you meant if you had a good head gasket and changed it, the mixture would change! The above sounds legit.

 

[Nodroz]

Alright, this is what I've done today:

1. Adjusted intake valve clearance. (It was 0.00mm!)
2. Adjusted spark plug clearance to 0.75mm.
3. Cleaned spark plug.
4. Removed the black ring. After reading the carburetor manual, it appears to be a very important piece. The hole is not open, it's closed. Here comes the air and fuel together, which creates the mixture.

If you don't understand me, look here: http://cssportal.css-club.net/honda/PowerProducts/contents/20101020142936_4557.pdf

I just have a normal stock airfilter, new however.

Tonight it's time to test the new carb settings. Then I'll see if he's running good.

Now my next problem:
I don't like the throttle set up. It's pretty crap actually. Sometimes the spring doesn't even return when I want to idle, so this definitely need to be changed.

As far as I can see, the spring they used it a pull spring. I think we should use a push spring, so it always goes back to idle. However, when you press the pedal, you'll be pulling the push spring, which isn't good either. Do you guys have any ideas of how to set this up?

Regards,
Nodroz

 

[Doc Sprocket]

Yes- that throttle linkage is horrible. The spring return to idle should always be done with a tension (pull) spring, but better than that. Set up a new spring so it always has tension, even in the idle position. Now, that long curvy spring- is that the actual link to the carb? I don't like that very much. Nothing wrong with using a spring for that, but there's a lot of slack in it. Plus, I don't like the wat it drags that rod connector around. The extra drag will not do you any good.

 

[Nodroz]

Yes- that throttle linkage is horrible. The spring return to idle should always be done with a tension (pull) spring, but better than that. Set up a new spring so it always has tension, even in the idle position. Now, that long curvy spring- is that the actual link to the carb? I don't like that very much. Nothing wrong with using a spring for that, but there's a lot of slack in it. Plus, I don't like the wat it drags that rod connector around. The extra drag will not do you any good.

I don't quite understand what you're trying to say. What will I have to do to get a good operational throttle setup?

 

[r_chez_08]

IMO, replace the rusty spring and connector with a solid linkage to the carb. You can use a coat hanger or similar. You can have a spring connection but it isn't really required. Also, tighten everything up, you don't want all that slack!

I also have a return spring on the butterfly lever on the carb. This is an extra safety measure if the linkage was to come off.

The short return spring looks crap. I would get a longer stronger one that goes To another position. JMO.