Cylinder Head Won't Budge

[RustyTank]

If the head was still on the engine I would tell you to screw a compression tester hose into one of the center cylinders and after placing the nuts back on the studs loosely, plug it into an air hose. In a 72mm bore 125 PSI makes about 800 pounds of force. Don't launch your head nuts loosely back on the studs if you try it. otherwise put it in a bucket of diesel oil with a pint or two of lacquer thinner in it for a few days if you are not in a hurry. It will clean the heck out of it, but it will destroy your valve seals. If you use a plastic bucket make sure it is marked PE or HDPE on the bottom so the mix doesn't eat into the bucket.

I'm in no hurry, I know these things take time. I appreciate the info about the compression, I'm sure I can use that knowledge down the road. I think I'd rather try the soaking technique at this point.

You can pour the same mix into the cylinders if you flip it upside down, I would go 50/50 an the lacquer thinner and diesel mix in this case.

Is this an alternative to soaking the entire thing with the same result expected? If so, I suppose in this case I'd be saving the valve seals? Maybe I've got the wrong impression.

[Grimly]

Give up any notion of re-using those crusty old valve seals.
Total waste of time, and they're not expensive anyway. Even better is the opportunity to fit Viton seals instead.

[RustyTank]

Give up any notion of re-using those crusty old valve seals.
Total waste of time, and they're not expensive anyway. Even better is the opportunity to fit Viton seals instead.

Oh yeah, I totally agree Grimly. I'm def planning on replacing them. I was just curious about the process of soaking the diesel/lacquer thinner mix in the cylinders. I guess I was just trying to understand the difference between the two processes metalfab suggested. I'm 95% sure I'm going the soaking route. Currently looking for a bucket of some sort big enough that'll fit the head and block together. And I'll look into the Viton valve seals. Thanks for the suggestion.

[Carter Turk]

What about wood shims wedged under the intake/exhaust area between fins along with penetrating oil?

Maybe 1 on the outside of cylinder 1-4 & 2 more on each side crossways on 2-3.

Seems the wood would squish before a fin breaks.

[Nessism]

A wood shim aimed at the head gasket would likely work too. There are easier and cheaper ways than buying a tub and 5 gallons of some concoction that you will have no easy way to dispose of.

https://www.homedepot.com/p/8-in-Wood-Shims-12-Piece-per-Bundle-WSSHW08/300723328

[Tom R]

I just came across the same issue on a CB750 I’m taking apart.... I used a foot long left over length of hand rail through the cylinder and gave it a couple whacks with a hammer. I just held the cylinder block with one hand. Not a very eloquent solution, but it works.

[Nessism]

I just came across the same issue on a CB750 I’m taking apart.... I used a foot long left over length of hand rail through the cylinder and gave it a couple whacks with a hammer. I just held the cylinder block with one hand. Not a very eloquent solution, but it works.

That's what I'm talk'n about!

Get a piece of wood that's roughly the same width as the cylinder bore. You don't want a skinny piece of wood which will press on the valve heads.

[chuck hahn]

sure ALL the 10mm bolts are out?

[Tom R]

It doesn’t take much... in my case it was the locating dowels that didn’t want to let go.

[RustyTank]

sure ALL the 10mm bolts are out?

Yup...I've checked so many times

I got all of em, including the two side bolts, as well as the front one that's often missed.

[RustyTank]

tel:2635801[/URL]"]2635801[/URL]]A wood shim aimed at the head gasket would likely work too. There are easier and cheaper ways than buying a tub and 5 gallons of some concoction that you will have no easy way to dispose of.

Nessism, you make a good point.

tel:2635803[/URL]"]2635803[/URL]]I just came across the same issue on a CB750 I’m taking apart.... I used a foot long left over length of hand rail through the cylinder and gave it a couple whacks with a hammer. I just held the cylinder block with one hand. Not a very eloquent solution, but it works.

tel:2635806[/URL]"]2635806[/URL]]That's what I'm talk'n about!

Get a piece of wood that's roughly the same width as the cylinder bore. You don't want a skinny piece of wood which will press on the valve heads.

I suppose if there’s anyplace to take a wack at it that’s the spot. Ok then, over the next couple days I'll give this a go and report back.

[RustyTank]

SUCCESS! Thanks everyone for your help, specifically to Tom and Nessism for presenting the method and the encouragement.

[Nessism]

SUCCESS! Thanks everyone for your help, specifically Tom for presenting the method...

[metalfab]

I'm in no hurry, I know these things take time. I appreciate the info about the compression, I'm sure I can use that knowledge down the road. I think I'd rather try the soaking technique at this point.



Is this an alternative to soaking the entire thing with the same result expected? If so, I suppose in this case I'd be saving the valve seals? Maybe I've got the wrong impression.

You have the right impression, it salvages valve seals if they are good. It also allows you to soak the stuck area with the cylinders off of the engine. Lacquer thinner is the base of many carb cleaning products like spray carb cleaner, even seafoam has a little similar petroleum product in it. Lacquer thinner is a very good carb/parts cleaner, it is very flammable. If you can safely handle gasoline, handling lacquer thinner isn't much different.

I saw you got it off, there is more than one way to skin a cat.

[RustyTank]

You have the right impression, it salvages valve seals if they are good. It also allows you to soak the stuck area with the cylinders off of the engine. Lacquer thinner is the base of many carb cleaning products like spray carb cleaner, even seafoam has a little similar petroleum product in it. Lacquer thinner is a very good carb/parts cleaner, it is very flammable. If you can safely handle gasoline, handling lacquer thinner isn't much different.

Thanks a lot for that info metalfab. May come in handy in a future build.