Topic: Is this cylinder head salvageable

[FrédéricVigenon]

Dear members
I have a little question about this cylinder head. I'm doing a full rebuild on this engine and have started to clean parts.
This engine has been sitting for a long time with the previous owner and when I removed the cylinder head gasket and cleaned the head I saw this pitting in the cylinder head.
Its to deep to get rid off with skimming the head but being an aircooled engine is this a real big problem or could I get away with this pitting.
Is there anybody here who has welded one off these heads and is that a valid option?
Photo's are attached.

Thanks in advance.
Frédéric

[willbird]

We have an expression about whether the juice is worth the squeeze :-). I'm sure the more experienced folks will weigh in but I have seen a lot of vids where people tig weld badly damaged aluminum heads and rework them.


Bill

[simon#42]

im sure it could be welded but unless the head has had a lot of expensive port work done to it you would be better off looking for a different head .

[CycleRanger]

Hello! Welcome! 

Wow, that's some pretty deep pitting. Perhaps it could be repaired but I'd probably look for a replacement first.

[Alan F.]

Is JBWeld not an option?

[willbird]

Is JBWeld not an option?

The operating temperature is what gave me pause, if that was a hydraulic manifold at work and an O ring sealed there we have use the correct kind of Devcon before but temperature never goes about 130F in any of our hydraulic systems.

[Alan F.]

https://www.jbweld.com/product/j-b-weld-twin-tube

"At room temperature, J-B Weld™ sets in 4-6 hours to a dark grey color. A full cure is reached in 15-24 hours. J-B Weld™ has a tensile strength of 5020 PSI and sets to a hard bond overnight. It can withstand temperatures up to 550ºF when fully cured."

[MauiK3]

I used to work with high temperature RTV (silicone) on steam turbine case joints. I wonder if this is an option.

[Rookster]

Its not worth the expense to rebuild the head then hope the JB Weld doesn't leak.  If it leaks then you are looking at engine out unless the frame is cut.  The CB750 is also known for head gasket leaks.  Sometimes its the pucks but alot of times its the head gasket.  I would save yourself the trouble and get a different cylinder head.

Scott 

[newday777]

I used to work with high temperature RTV (silicone) on steam turbine case joints. I wonder if this is an option.

A very poor suggestion 😕

[Alan F.]

I've been reading and watching some videos where JB-W is used on many types of engines from over-the-road diesels to drag racing big blocks to exotic cars, it's all been done.

Then I read someone recommending Marine-Tex, which is a similar but far superior product that I used to use at work decades ago.
https://www.amazon.com/Marine-Tex-RM305K-White-oz/dp/B0014419V0

[jlh3rd]

no dog in the fight.
FWIW
I like Project Farms.....so..

[Flyin900]

I have used Tech Steel to rebuild fins on an air cooled engine with good results. Faster set up than JB Weld, like 15 mins and full cure in 1 hr.
It is rated at 500F, so if you in that range likely other issues are happening. Yet your internal so who knows what temps your getting there.
The suggestion of head replacement is the best then you know what your dealing with from the get go.

[BenelliSEI]

I’d look for another one……

[tool14]

i would look for different head not worth time and trouble to repair.

[HondaMan]

While it looks like a K0/1/2/3 head, any of the 750 heads from a K0-K6 will drop right on. Even the head of the F0/1 engine would fit.
I might have one  around here somewhere. What year is the bike?

[MRieck]

That's a 550 head. If you're hard up it can be used after milling .010 or .015. The fire ring area is the important part and the corrosion doesn't look bad there. Oil drainage is via cam tunnel which doesn't look bad. Oil feed areas look OK too. I'd use a different head but it will work after milling. Pouring weld in the head isn't a good idea especially in the fire ring area....it removes the temper.

[bryanj]

As a 550 its same as 500 so there should be lots of used out there

[HondaMan]

That's a 550 head.

Aha! You're right, I have a 750 head on my bench and 750 on the brain... 

[grcamna2]

I’d look for another one……

I wouldn't use it.

[low-side]

I agree with what's been said.  It could be milled and even paired with a custom thickness head gasket, but it would probably be cheaper and easier to get another head.