Topic: CB750K head stuck to cylinders

[71 V12]

Hello again,

I am stripping down a CB750 K0 engine. All completely stripped except I can’t separate the the head from the cylinders. When removing the head from the engine the cylinders and head came together.

All of the fasteners including the rear 6mm bolt are removed, but it’s stuck. Obviously I don’t want to force it apart and break something. My usual method of separating stuck items is heat, either a hot air gun or butane torch.

The head and cylinders is way to big for this, I would not get enough heat into it.The only way I can think of getting it hot enough is to put in on the BBQ!

The rubber parts will all be replaced, so I am not concerned about them.

Is this a bad idea?

[markmyodb]

Did you remove the four M6 screws under the rubber pucks?

[71 V12]

Just checked, and I missed one in the dark depths - duh

[ekpent]

 Be careful in the bbq as the cylinder liners might fall out also. 4 screws hiding under the pucks.

[PeWe]

6 x M6. 4 under cam holder pucks, 2 on each side of cam chain tunnel.
The one over cam chain tensioner easy to forget.

[Stev-o]

I had the same challenge with my K4 after I blew a hole in the case. 

Used a wood shim as a wedge to separate the two....

[PeWe]

Some Honda head gaskets had sticky surfaces that glued it together.

[Remcod]

Don't use force on the intakes and don't ask how I know this

Verstuurd vanaf mijn SM-A415F met Tapatalk

[71 V12]

Well, I have removed the one 6mm screw had missed lurking in the goo under the puck.

To recap, cylinder and head removed together from cases, I have now removed 4 x 6 mm screws under the pucks and one 6mm bolt at the centre rear and I still can’t shift the head.

Perhaps being over cautious but a little reluctant to tap wooden wedges between the head and cylinders.

Is heat worth trying? At what temperature do the liners become loose?

[goodtryer]

Maybe the dowel pins are holding it in place.

There are some specific spots where it is ok/acceptable to pry between the head & cylinder. I know it's shown in Mark's book.

[robvangulik]

Read reply #2.

[71 V12]

The 4 screws under the pucks have been removed, #14 in the diagram

The single bolt at rear has been removed #19 in the diagram. Bolt #20 does not exist, I think this was added later in production, remember I working on a die cast K0.

Am I missing another bolt/ screw?

[Kevnz]

Could you not use a length of timber up through the barrels and tap it free from beneath? Valves closed if cam out, perhaps shape the wood to better fit the combustion chamber.

[Hoosier Honda]

Could you not use a length of timber up through the barrels and tap it free from beneath? Valves closed if cam out, perhaps shape the wood to better fit the combustion chamber.

That's what I was thinking also. "There's nothing like a nice piece of hickory" 

[754]

Wad up a rag in there, then use a 2x2 or 2x3  whatever fits, and give it a few raps  with a hammer.
 Make sure it cant fall..

[madmtnmotors]

There are two pry points, one is above the 1/2 intake spigots and the other is above the 3/4 intake spigots. I found these pry points after breaking a couple fins on a project where the P.O. had used some industrial adhesive on both sides of the head gasket. When I finally pried them apart the head gasket actually delaminated with half the gasket stuck to the head and the other half stuck to the cylinders. Look carefully and you should find the two areas I'm talking about. There is solid material at these two locations and no force would be exerted on any of the fins.