Author Topic: cylinder head cover gasket replacement without removing the engine  (Read 1047 times)

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Offline _mark

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Hello. After rebuilding the motor (750 K1) I'm experiencing leakges from such gasket.
Is it possible to replace it without removing the engine ? thanks and Regards.

Offline robvangulik

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #1 on: June 08, 2023, 05:56:10 AM »
It can be done, but the risk of tearing your new gasket is quite large.....

Offline _mark

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #2 on: June 08, 2023, 08:07:58 AM »
It can be done, but the risk of tearing your new gasket is quite large.....

well... yes the idea is to cut the new one on the rear side (where oil doesn't lay against the walls) and then insert it...

Offline Alan F.

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #3 on: June 08, 2023, 08:33:16 AM »
Is there any type of rubber gasket available for this cover?
Seems like it'd be easy to stretch a rubber gasket around the cover from the top and slip it into place without having to slip it in from the side.

http://forums.sohc4.net/index.php/topic,15529.0/all.html
« Last Edit: June 08, 2023, 08:41:20 AM by Alan F. »

Offline seanbarney41

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #4 on: June 08, 2023, 01:08:05 PM »
No rubber gaskets that i have ever seen or heard of...I have done this before but it was so awkward that the gasket still leaked even after replacement.  Basically had to totally unbolt the engine and rotate it forward enough that cover could be raised enough to weasel the gasket in place...yeah frame is likely gonna get gouged and no it did not work anyway...maybe with an extra set of hands....but then, probably still better off just biting the big one and pulling that 200lb lump.
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Offline Stev-o

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #5 on: June 09, 2023, 07:38:58 AM »
....but then, probably still better off just biting the big one and pulling that 200lb lump.

Or installing a frame kit!
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Offline MauiK3

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #6 on: June 09, 2023, 08:01:25 AM »
Frame kits seem to be a good idea but I guess I'm just not comfortable with cutting such an important part.
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Offline Stev-o

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #7 on: June 09, 2023, 08:59:41 AM »
Frame kits seem to be a good idea but I guess I'm just not comfortable with cutting such an important part.

I can understand that.  I have one on my K3 but it came with a homemade kit, Franks kit was a big improvement.



BTW - the later model CB's have one.
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Offline _mark

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Offline britman

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #9 on: August 28, 2023, 08:59:19 AM »
If you are leaking from that point your gasket may have been installed upside down.  I can tell you from experience having just changed mine out recently.  (It was easy access for me since the frame rails had been cut.)  I almost did it in my case, it looks good around the permitter of the top of the valve train, but the front extended front section misses the gasket hole completely.  The guy who posted the above video did the same thing.....

Offline CycleRanger

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #10 on: August 28, 2023, 09:04:40 AM »
If you are leaking from that point your gasket may have been installed upside down. 

It's easy to do. Ask me how I know.. ::)
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Offline PeWe

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #11 on: August 28, 2023, 09:41:05 PM »
Frame kits seem to be a good idea but I guess I'm just not comfortable with cutting such an important part.

I can understand that.  I have one on my K3 but it came with a homemade kit, Franks kit was a big improvement.



BTW - the later model CB's have one.
Both my CB750 have Franks kit.
I had to cut my K6 to rework, replace cyl studs. That was just the beginning of several cyl, head and cam replacements/adjustments.

My K2 frame was cut when bought but needed an upgrade by Frank.
I have had really good use of it numerous times.

Shame that Honda did not do it. At least a Service Bulletin how to cut with a kit as spare part.

That should handle eventual value for stock restorers.
A frame kit really is an upgrade solving a design flaw by Honda.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Online HondaMan

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #12 on: August 30, 2023, 09:05:22 PM »
There are also certain gaskets out there that leak. A lot. I have had the best luck (with NOT leaking) with the Vesrah gaskets.
The ones that leaked every time were the ones that are so stiff that they seem to be made of thin pressboard. They didn't seal anywhere on that engine. The kit came with the engine from the owner: before I shipped it I swapped out all of the gaskets (including the head gasket) to a Vesrah kit.

I've also seen quite a few nicked-up head gasket surfaces on the top of the head. They came form being dropped, or having something dropped onto them, or some other sort of industrial accident: in some cases I've had to have the area welded up and then filed it flat down again in order to seal, then used Hondabond to help it out. Hint: Hondabond-sealed gaskets are murder to remove again...do it to just one side if possible.
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Offline PeWe

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #13 on: August 31, 2023, 02:08:37 AM »
Important that all holes lines upp with head.
Aftermarket gaskets have often several holes not matching head.
In front of cam chain tunnel, 2-3.
And some more.

If trying to force the M6 bolt to go thru it will grip the gasket and tear it apart. Especially the cam chain tunnel holes. A piece of the gasket can fall into the engine to later be found in oil pan.

I have also seen that the cam tower can be an obstacle for gasket to fit. Gasket need to be cut slimmer, not only trim all holes where not aligned.

The light green Honda gaskets usually much better. Can be reused too.
I have lifted several engine covers and mounted them again without changing the gasket.

Make sure the gasket is flipped right before adjusting it ;D
« Last Edit: August 31, 2023, 09:27:01 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Floshenbarnical

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #14 on: August 31, 2023, 08:00:01 AM »
If you are leaking from that point your gasket may have been installed upside down.  I can tell you from experience having just changed mine out recently.  (It was easy access for me since the frame rails had been cut.)  I almost did it in my case, it looks good around the permitter of the top of the valve train, but the front extended front section misses the gasket hole completely.  The guy who posted the above video did the same thing.....

I did the same thing, also. With an aftermarket gasket, no less. Pissed oil everywhere until I replaced it with an OEM one.

You can still order the OEM gasket. It comes with an alignment notch to help you install it correctly. The alignment notch should sit by the exhaust valve of cylinder 1.
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Offline PeWe

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #15 on: September 02, 2023, 05:06:25 AM »
I have seen the notch but never had that in mind.

One thing us usually clear, it does not matter how I flip it. First try usually wrong ;)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline cfairweather

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #16 on: September 02, 2023, 07:30:59 AM »
I didn't like the idea of cutting the frame, but now that I did it, it was a good decision.  I did not want to do any welding because it seemed risky and expensive, so I used JB Weld to attach bungs to the frame ends.  To make the bungs fit snuggly, I inserted small sections of 7/8" tubing from an old set of handlebars that I had in the shop and used JB Weld around these too.  You must clean the metal surfaces with a steel brush to get everything properly prepared for the epoxy.  In certain situations, JB Weld can be used and it is very, very strong when used correctly.  I believe this is one of those uses where it can be used instead of welding.  I also threaded a screw into the bung to make it even stronger, but this is probably overkill.
Before you cut anything, screw in two small 1/4" steel/aluminum sections underneath the thin vertical wings that attach the lower bars to the top bar.  This way, you can ensure the cut section will be remounted as it was before you made the cut.  I inserted the section into place and took a few pictures so you can see what it looks like.  I did not screw it into place because I am still working on the engine.  Trust me, this is as strong as it was before the cut.

 
« Last Edit: September 02, 2023, 07:47:37 AM by cfairweather »

Offline PeWe

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Re: cylinder head cover gasket replacement without removing the engine
« Reply #17 on: September 02, 2023, 09:04:42 AM »
Look good, almost invisible! ;)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967