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Author Topic: What is this round cover on the bottom of the crankcase  (Read 1029 times)

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Offline Randol

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What is this round cover on the bottom of the crankcase
« on: December 28, 2014, 04:34:49 PM »
I don't know what this is for.  There is an ear on the oil pan that appears to hold it in place. I tried lightly tapping on it from the inside to see if it would pop out. I thought I'd check before I got carried away. I don't see any reference to it in the parts diagrams or in the manual. Is there an o-ring I need to be concerned about?
Bike is a 1978 CB750K8
Thanks

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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: What is this round cover on the bottom of the crankcase
« Reply #1 on: December 28, 2014, 06:27:08 PM »
It's nothing but it needs to stay in place as is so leave it alone.
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As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline goldarrow

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Re: What is this round cover on the bottom of the crankcase
« Reply #2 on: December 28, 2014, 06:37:05 PM »
Nothing removable there.  It's part of case design
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Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

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CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


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Offline Whaleman

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Re: What is this round cover on the bottom of the crankcase
« Reply #3 on: December 29, 2014, 07:27:41 AM »
Yes, it can be removed. I removed mine by tapping out from the inside. There is a big o-ring that seals it. The o-ring is not listed as a Honda part. i was able to go to an o-ring company close to me and the owner found a Viton o-ring the exact size. Don't remember the size. Dan
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Offline Whaleman

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Re: What is this round cover on the bottom of the crankcase
« Reply #4 on: December 29, 2014, 07:35:46 AM »
Now if you ask me why it is there I have no clue. Dan
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Offline goldarrow

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Re: What is this round cover on the bottom of the crankcase
« Reply #5 on: December 29, 2014, 09:47:47 AM »
I stand corrected.  Good info, I never try to remove it. 
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Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline Raul CB750K1

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Re: What is this round cover on the bottom of the crankcase
« Reply #6 on: December 29, 2014, 12:09:25 PM »
Many times plugs that appear to serve to no special purpose are just that - plugs. A hole was necessary to machine some oil passage and it could only be done from that side, needing a plug afterwards. Don't know if that is the case this time but I've seen it before.
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Offline Whaleman

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Re: What is this round cover on the bottom of the crankcase
« Reply #7 on: December 29, 2014, 04:06:29 PM »
I think anyone who is going to bake the case after painting should pop this out. If the o-ring looks ok, just put it back together after with some Hondabond on it. Kinda like came tower pucks. This is what I did. Dan
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