Cylinder head problems

[watty51]

Hi All,
Just took cylinder head off Cb350f due to 2 maybe 3 new spark plug threads nead a re thread, and had a few problems removing it, this is why.

The PO had used a silicone gasket maker on top of the cylinder head gasket and it  “super glued” the cylinder head on....any now the reason why they did this become apparent when I managed to get it off.

The face where the gasket sits is damaged and I’m presuming the silicone was put over these areas to provent a leak, in fact I had no leaks at all. The damage does look a lot worse on the photos though.

Is this cylinder head repairable ?

Looking at the valves the engine has been running rich so needs a good decoke, the exhaust valves have a mark in the middle of all of them, ( see photo) what is this due to or is that how they are meant to be.

And finally if it’s saveable does anyone no where I can get the work done, West Midlands, Warwickshire area but don’t mind travelling or posting out.

Hope I’ve explained everything ok.

[Trigger]

Depends how deep they are on the head, a skim may clean it up if not too deep 

[watty51]

Hi all,

Are these carburetor insulators meant to be a soft rubber like the carb type because these ones are a hard rubber.
Thanks.

[Trigger]

Soft but, not that soft. Hard to tell how soft something is without having it in the hand. Take them off, boil a kettle and put hot water in a bowl, drop them in for a couple of minutes and should go soft but won't stay soft. Cracks are more important than softness.

[taysidedragon]

Soft but, not that soft. Hard to tell how soft something is without having it in the hand. Take them off, boil a kettle and put hot water in a bowl, drop them in for a couple of minutes and should go soft but won't stay soft. Cracks are more important than softness.

There's a joke there somewhere! 😂😂

[SteveD CB500K0]

Soft but, not that soft.

They have to be stiff enough to support the carbs (and they ain’t light) but soft enough to push over the mounts.


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[Tomb]

Be aware that when skimming heads, valve timing may be affected, added to that a worn camchain could put timing quite a way out.

Ways round this are thicker head or base gaskets. I've made copper head gaskets for this reason, and used two base gaskets or two head gaskets. On a turbo NOS race engine we use an aluminium decompression plate under the barrels.

On the flip side, I have successfully used heads with that much corrosion or damage, The compression area of the gasket is in the reinforcing around the bores, as long as the gasket is sufficiently gripped to support this reinforcing, the oil sealing can be assisted with some sealant. Try laying the gasket on the head to see how much does the sealing.