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Hey guys, so I finally got the motor off of the frame and up on the bench to check it out. I pulled the rear cover and down near the spark plug i found what i believe to be a crack. Not sure if it’s an issue or normal or even what to think of it because I’ve never heard it run..or ran into this. What is the culprit do you think?
291235
 

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2002, Shadow Spirit 1100
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It looks like a crack but I have never seen a perfectly straight crack with a perfect angle at the end of it. It may be a casting mark. You could have it magnafluxed to find out if it is a crack.
 

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1983 Honda vt750 Shadow
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You could take a picture of the other cylinder to compare.
If this one is looking like a crack and the other doesn't, pour some acetone (or brake cleaner) down there and see if it seeps through to the inside. It will evaporate and not harm anything.
It doesn't look "freshly wet" to me .
 
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Discussion Starter #4
You could take a picture of the other cylinder to compare.
If this one is looking like a crack and the other doesn't, pour some acetone (or brake cleaner) down there and see if it seeps through to the inside. It will evaporate and not harm anything.
It doesn't look "freshly wet" to me .
This is a good idea! I’m going to try this
 

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It appears to be a casting crack. A compression test should be in order.
 
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1999 Shadow 750 ACE VT750CD3 Modified
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A compression test is not going to show anything,
I may be confused with what I'm looking at but that looks like the top of the head down the park plug access hole.
That round thing is the backside of a casting plug, so not combustion pressure, maybe coolant, or oil but no evidence of leakage so maybe nothing hits it and maybe nothing will unless the crack grows.
I'm thinking this plug in the picture is likely the other side of it and the crack initially occured when they plugged the new casting.

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A compression test is not going to show anything,
I may be confused with what I'm looking at but that looks like the top of the head down the park plug access hole.
That round thing is the backside of a casting plug, so not combustion pressure, maybe coolant, or oil but no evidence of leakage so maybe nothing hits it and maybe nothing will unless the crack grows.
I'm thinking this plug in the picture is likely the other side of it and the crack initially occured when they plugged the new casting.

View attachment 291237
Do you think it’s anything to be worried about then? As far as i can tell there is no leak there but you are right it’s the hole where you drop a socket down to install or pull the spark plug
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Do you think it’s anything to be worried about then? As far as i can tell there is no leak there but you are right it’s the hole where you drop a socket down to install or pull the spark plug
I don't know, I have other similar heads, but no VT500 experience.
It is really your call, it will be fine until it isn't when ever that is, could be tomorrow could be forever.
Somebody familiar with the VT500 heads might look at it and say "Don't worry about it they are almost all like that", but that's not me.
If one wanted to repair it, it is in a difficult location.
Finding a used head would be an option, but COVID seems to have doubled the prices on a reduced selection of parts, so I'd be putting that off as long as I could.

I'd also be torn between pulling the head to see if it was cracked right through or just riding it.
The more I think about it, if it was mine I might just ride it for the sake of science. (-;
 

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2007 VT750DC Spirit “chopper”
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Looks like the back side of a screw in freeze plug with a sand-casting mold line going across to me, if that were cracked coolant would be filling up that spark plug hole and would have left a trace/witness mark but that’s really just speculation from the single picture provided and since you’ve never heard it run I assume it never built coolant pressure enough to know for sure if it leaked from there. Looks awfully clean though, so I still say it’s a sand-cast mold line.

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If you look at used cylinder head pictures you can see the other side of that plug is a wide flange allen fastener, that would be a difficult place to crack a cylinder head, unless it had just water in it and froze I suppose.
 

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1999 Shadow 750 ACE VT750CD3 Modified
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Looks like the back side of a screw in freeze plug with a sand-casting mold line going across to me, if that were cracked coolant would be filling up that spark plug hole and would have left a trace/witness mark but that’s really just speculation from the single picture provided and since you’ve never heard it run I assume it never built coolant pressure enough to know for sure if it leaked from there. Looks awfully clean though, so I still say it’s a sand-cast mold line.
If you look at used cylinder head pictures you can see the other side of that plug is a wide flange allen fastener, that would be a difficult place to crack a cylinder head, unless it had just water in it and froze I suppose.
That plug was my choice too in post #6. (-;
Unless that crack propagates further it is not going to hit coolant.
AFAICT that area is just the space between the cylinder water jacket and the cam drive slot, as it sits it is open on top and a void beneath.
The oil supply to the heads on these are by external lines, as Honda didn't use that space until ~1991 and that plug area is protected from return oil at the top by the valve cover.
On later engines there is a drain hole from that area to prevent water build up, I don't know about these heads, but freezing at that point could definitely be a possible cause.
 
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