Help......head question

[stevec8831]

Need some help guys. My simple xs650 project may have just turned into something more. As I was getting ready to start taping off my engine to get it ready for a new paint job. I removed one of the rear valve covers and found a piece of broken metal. Now I'm not sure how to move forward. The bike was running fine before the build and all I was planning to do was some cleaning up, repainting and changing a few items. Nothing major was planned. All I've done to the bike is tear it down, stripped some paint, some welding and grinding on the frame and replaced some filters. I've done nothing to cause this break. I'm just glad I found this before I got all done the build and started the engine. I've found where the broken piece came from and attached a few pics and a diagram to try and show it's location. It's a small piece of the head between the rear points side valve and the cam. My question to everyone is what should I do? Will this missing piece affect the engine? Has my simple build turned into having to tear it down and replace the whole head? The bike is just going to be a bar hopper and I'm not planning on trying to break and land speed records. All I want is for it to look good and run on a daily basis. Any help anyone can give me will be greatly appreciated.

 

[5twins]

Did you find it inside the cover? It looks to me like a broken outer cooling fin. That would be no problem. Inside, maybe, depending where it came from.

 

[jd750ace]

If it is that narrow web beneath the rocker arm there, and it's on the intake side of the head, it will probably be OK. If it were on the exhaust side, I would wonder if it would affect cooling of the valve seat any, since you lost a little surface area for the oil to exract heat from. I'd have to be looking at an open head and see how it ties into the other areas to be positive, but I'm pretty sure it will live. Hope that's the only piece.

 

[stevec8831]

When I removed the valve cover it was laying next to the valve spring. I outlined the area in red on the drawing diagram and you can see it in the photo of the valve spring. Just behind it. I wish it was as simple as a broken cooling fin. If it was that I wouldn't be worried and just move on with the build.

Did you find it inside the cover? It looks to me like a broken outer cooling fin. That would be no problem. Inside, maybe, depending where it came from.

 

[stevec8831]

i've looked in all the valve areas by removing all the covers and it seems to be the only piece. I replaced the sump oil filter yesterday and found nothing there as far as pieces of metal. It looks to have broken off in one piece. Not sure what would have caused this to break off in the first place. It is definitly on the intake side. I outlined the area in red on the drawing diagram which shows all areas of the top of the head.

If it is that narrow web beneath the rocker arm there, and it's on the intake side of the head, it will probably be OK. If it were on the exhaust side, I would wonder if it would affect cooling of the valve seat any, since you lost a little surface area for the oil to exract heat from. I'd have to be looking at an open head and see how it ties into the other areas to be positive, but I'm pretty sure it will live. Hope that's the only piece.

 

[Olie]

It's part of the oil dam in the head. Basically it's there to keep the oil spray from the cam from "drowning" the valve. I wouldn't worry about it though. As long as there's not more pieces floating around which you already said there wasn't.

The bigger question is what caused this? Normally there's nothing close to that dam to cause any damage.

 

[stevec8831]

Here is a better pic. I outlined in red where I believe the broken piece came from. You have to click on the pic to see the the outlined area. I can definitely see the difference between the the points side valve area (broken side) and the advance side valve area. Thats how I could tell where it broke off from. You have to click on the picture I posted in order to see the red outlined area clearly.

 

[stevec8831]

Thats the first question I asked myself once I figured out where it came from. The bike was running fine before the build and I've done nothing to cause this to happen. I replaced the o-ring and gasket behind the points housing because of a oil leak. But thats the only thing I've done in this area.

It's part of the oil dam in the head. Basically it's there to keep the oil spray from the cam from "drowning" the valve. I wouldn't worry about it though. As long as there's not more pieces floating around which you already said there wasn't.

The bigger question is what caused this? Normally there's nothing close to that dam to cause any damage.

 

[XSLeo]

As olie said it came from the oil dam. This dam helped control the oil flung off the spinning cam toward the intake valve. About the only thing that might happen will be the vaccum on the intake stroke may pull a bit more oil down through a weak or bad valve stem seal. With a good seal I doubt there will be any problem.
If you are really worried take the head and the piece to a welding shop. They can weld in the broken area to match the piece. A bit of careful grinding to make it look pretty and your golden.
Me, I would just run it.
Leo

 

[gggGary]

We agree it's the oil dam There was an old thread on this exact issue, not sure the OP ever told us what he did. I'd run it and not worry, well a little but I am that way...

 

[stevec8831]

Thanks to everyone for the info. It looks like I will be moving forward with the build as planned then. I just wasn't sure if it was something I should be worried about. It would totally suck for me to continue on investing more time and money into the project, just to have it blow up in my face on the first run after I was finished. I feel allot better moving forward now and thank everyone for your help and information once again. One more reason why I love this site and am glad it is around.