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Head Gasket Leak CA72.

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Waveblaster
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Post by Waveblaster » Mon Dec 08, 2014 8:31 am

There should be an aluminium plate between the two gaskets . Item 16
http://www.cmsnl.com/honda-ca77-dream-t ... ml#results

Another thing to perhaps check, did you have the studs and 6mm nuts done up either side just under the spark pugs?

The head studs should be different lengths. look at the top cover they are different depths.

LOUD MOUSE
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Post by LOUD MOUSE » Mon Dec 08, 2014 10:38 am

The metal plate may be aluminum or steel. ........lm
Waveblaster wrote:There should be an aluminium plate between the two gaskets . Item 16
http://www.cmsnl.com/honda-ca77-dream-t ... ml#results

Another thing to perhaps check, did you have the studs and 6mm nuts done up either side just under the spark pugs?

The head studs should be different lengths. look at the top cover they are different depths.

deafanddiabetic
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Location: Nebraska

Post by deafanddiabetic » Mon Dec 08, 2014 2:13 pm

I did have the lock washers and nuts by the spark plugs on, torqued them to 16ft/lbs as the manual did not have an amount for their torque.

Hmm, I didn't know about that plate. When I first ran the engine before rebuild there was no leaks of any kind so when I pulled it apart I only found two paper gaskets under the top cover, there was no aluminum/steel gasket there. I will have to order one of those as well.

mike1969
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head gasket

Post by mike1969 » Tue Dec 09, 2014 4:36 pm

D&D, I have the plate you need. $5.00 plus actual shipping. pm me if interested. Mike

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G-Man
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Post by G-Man » Wed Dec 10, 2014 6:43 am

Torque for those 6mm studs by the spark plugs should be a lot less than the 8mm barrel studs. You are in danger of pulling them out if you use the same value.



G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
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'67 S90 '77 CB400F

deafanddiabetic
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Location: Nebraska

Post by deafanddiabetic » Tue Dec 23, 2014 7:43 pm

Thanks to mike1969 and oldStan for getting me the breather shield and another flange.

I now installed the head gasket, knock pins, o-rings and put the "open" gasket on top of the head, followed by the metal breather shield, finally the rubber gasket that looks exactly like the breather shield, with the two holes/ports in both of those gaskets towards the exhaust of the engine.

My head nuts torqued much better this time, I got them to 24lbs/in and tightened the nuts below the spark plugs to quite firm, but not stupid and break them firm. Next, I made sure the exhaust and intake valves were at .01mm, they hadn't moved a bit since removing the head.

I let it sit overnight and retorqued the head nuts to 24 again, some had fallen a point or two.

So, upon running the bike the left side front of the head gasket does NOT leak anymore, but the front right does. I can even watch small bubbles appear while shining a light at the gasket while it's idling. It idles beautifully at about 900, but it still leaks.

I did a compression test again, the non-leaking side has 90, the leaking right side has 125.
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LOUD MOUSE
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Location: KERRVILLE, TEXAS

Post by LOUD MOUSE » Tue Dec 23, 2014 7:59 pm

Just a guess but it may be what another member of this forum had.
The knock pin is to tall/long. ..........lm
deafanddiabetic wrote:Thanks to mike1969 and oldStan for getting me the breather shield and another flange.

I now installed the head gasket, knock pins, o-rings and put the "open" gasket on top of the head, followed by the metal breather shield, finally the rubber gasket that looks exactly like the breather shield, with the two holes/ports in both of those gaskets towards the exhaust of the engine.

My head nuts torqued much better this time, I got them to 24lbs/in and tightened the nuts below the spark plugs to quite firm, but not stupid and break them firm. Next, I made sure the exhaust and intake valves were at .01mm, they hadn't moved a bit since removing the head.

I let it sit overnight and retorqued the head nuts to 24 again, some had fallen a point or two.

So, upon running the bike the left side front of the head gasket does NOT leak anymore, but the front right does. I can even watch small bubbles appear while shining a light at the gasket while it's idling. It idles beautifully at about 900, but it still leaks.

I did a compression test again, the non-leaking side has 90, the leaking right side has 125.

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