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Cylinder heads can be removed with the engine in the bike.

Do you have access to a borescope? You might be able to tell if that is the issue before removing a cylinder head.
 

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1978 honda cx500
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Discussion Starter · #282 ·
Cylinder heads can be removed with the engine in the bike.

Do you have access to a borescope? You might be able to tell if that is the issue before removing a cylinder head.
I may, let me see if any of my friends have one. Of not ill look towards removing the head. Ive seen a few on ebay for cheap
 

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'84 CX650E that is evolving into a GL500
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Have a look at the section in the FSM that covers removing the heads.

What do you know about the history of this engine before you started working on it? I wonder if this is why you got such a great deal on it?
 

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1978 honda cx500
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Discussion Starter · #284 ·
Have a look at the section in the FSM that covers removing the heads.

What do you know about the history of this engine before you started working on it? I wonder if this is why you got such a great deal on it?

I didnt know much at all, the seller said it was complete and it ran before sitting for abour 10+ years. So i wouldnt be surprised if someone corroded away in the motor. But its definitely possible that he knew something else was wronf cause i did get it very cheap
 

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Discussion Starter · #285 ·
Ok so i found the problem! Dont mean to sound excited but im glad i found the issue, but now i need an expert to weigh in to let me know what the best next step is.

Ok, i removed the cylinder head, and lo and behold i saw one of the exhaust valves had chips on it! It was exactly like the other post in the forum i had seen. I will add photos on this post of a few things. It looks like there was damage done to the cylinder head. Im not fully sure how bad it actually is so im wondering if its still usable. I also took a photo of the piston head csuse there was some damage there as well, but not as bad. Also, i plan to order new gaskets from Murrays site, however what is this metal ring that also came out called? I may need a new one unless i can clean this one and reuse it.

But thank you again! This forum has been a gift from the gods, slowly solving all my issues but im getting there!
 

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1978 honda cx500
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Discussion Starter · #286 ·
Ok so i found the problem! Dont mean to sound excited but im glad i found the issue, but now i need an expert to weigh in to let me know what the best next step is.

Ok, i removed the cylinder head, and lo and behold i saw one of the exhaust valves had chips on it! It was exactly like the other post in the forum i had seen. I will add photos on this post of a few things. It looks like there was damage done to the cylinder head. Im not fully sure how bad it actually is so im wondering if its still usable. I also took a photo of the piston head csuse there was some damage there as well, but not as bad. Also, i plan to order new gaskets from Murrays site, however what is this metal ring that also came out called? I may need a new one unless i can clean this one and reuse it.

But thank you again! This forum has been a gift from the gods, slowly solving all my issues but im getting there!
 

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'84 CX650E that is evolving into a GL500
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The head you might be able to get away with if the valve seat isn't too bad. The piston I don't know.

It looks like something fell or was sucked into the cylinder and bounced around in there for a while

That metal ring is the middle of the head gasket (the actual metal part is called the flame ring because it protects the gasket from the heat in the combustion chamber).
 

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1978 honda cx500
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Discussion Starter · #288 ·
The head you might be able to get away with if the valve seat isn't too bad. The piston I don't know.

It looks like something fell or was sucked into the cylinder and bounced around in there for a while

That metal ring is the middle of the head gasket (the actual metal part is called the flame ring because it protects the gasket from the heat in the combustion chamber).
The valve seat is surprisingly unaffected, its just those parts around it that got damaged. I was wondering if i could grind them down? Just enough where its not a jagged surface. And is that flame ring reusable? It looks to be intact just dirty.
 

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Sorry you found that. I was hoping you'd have better news.

I'd just replace that and you can use any head from a 500.

I've also never seen a head gasket fail so thoroughly in one of these motors.

That and the valve between them would account for the cylinder having zero compression.

The bore looks OK and the piston face passable.

Oh .... I see your original head has a head breather. I would try to find a 78 79 head.

Or you could blank the other head breather and fit a bottle breather to the timing port.
 

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1978 honda cx500
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Discussion Starter · #292 ·
Sorry you found that. I was hoping you'd have better news.

I'd just replace that and you can use any head from a 500.

I've also never seen a head gasket fail so thoroughly in one of these motors.

That and the valve between them would account for the cylinder having zero compression.

The bore looks OK and the piston face passable.

Oh .... I see your original head has a head breather. I would try to find a 78 79 head.

Or you could blank the other head breather and fit a bottle breather to the timing port.
Yeah its not the news i wanted, but im glad i got an answer. And yeah i was going to ask if this was a common problem? I may buy that entire head, the valves alone i found are about 25 a piece on ebay, and im not sure if they made reproduction ones. So 45 for the entire thing seemed great
 

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1978 honda cx500
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Discussion Starter · #293 ·
Yeah its not the news i wanted, but im glad i got an answer. And yeah i was going to ask if this was a common problem? I may buy that entire head, the valves alone i found are about 25 a piece on ebay, and im not sure if they made reproduction ones. So 45 for the entire thing seemed great
I added a photo of the valves on the one i sent from ebay. I cant tell if they are good but they seem intact
 

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I'd just replace that and you can use any head from a 500.
Oh .... I see your original head has a head breather. I would try to find a 78 79 head.
I think a head from any CX500 though 1981 should work. I believe the '82 Custom got GL-style crankcase venting along with TI.
 

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1978 honda cx500
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Discussion Starter · #295 ·
I think a head from any CX500 though 1981 should work. I believe the '82 Custom got GL-style crankcase venting along with TI.
The pics i sent from ebay say they are from an 81 model. So that should be good? Also which part on mine is the breather?
 

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Discussion Starter · #299 ·
While you can't see the state of the seats, going by what can be seen the head generally looks good.
The other options on ebay are looking rough, and just the valves alone are being sold for 30 for used ones. 45 for the whole head seems like a better deal so ill give it a shot. I wonder if that will solve my problems, either way my rae san unit will be here friday which is super fast shipping, im pretty surprised considering im in the US. Fingers crossed but this bike should be good as new with these remaining parts
 
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