Author Topic: 79 CB750F bits found in oil pan.  (Read 1929 times)

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Offline thrutheframe

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79 CB750F bits found in oil pan.
« on: December 08, 2014, 09:23:11 AM »
I'm refurbishing a 79 CB750F.  It needed a new oil pan gasket.  When I pulled the pan I found lots of RTV boogers, what appears to be Hondabond boogers and a few other choice pieces of mystery.  Below you'll see pics.  The bits from left to right are:
 
Two plastic bits that look like the remnants of a plastic sleeve.

One ferrous chunk of unknown origin.

Five pieces of aluminum with threads that appear to have been a thread well at one time.

And

One aluminum washer 10mm ID x 20mm OD.

The motor overall has RTV at every gasket, I've had it running, compression was good, no odd noises.  I've had the valve cover off, the thread wells for the cover are intact.  Could someone have been try to sabotage a PO?  Catastrophic failure followed by a ham-fisted attempt to repair it?

Any ideas?

Thanks.
'74 cb 750 K4
'79 CB 650 http://forums.sohc4.net/index.php?topic=83981.0
'75 CB 360T
'90 RC31 Hawk GT

Offline thrutheframe

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Re: 79 CB750F bits found in oil pan.
« Reply #1 on: December 08, 2014, 10:17:32 AM »
Caj I'm curious about where your heli-coil comment comes from.  The threaded bits are definitely aluminum.  Can you elaborate?  I'm just trying to piece together the mystery here.
'74 cb 750 K4
'79 CB 650 http://forums.sohc4.net/index.php?topic=83981.0
'75 CB 360T
'90 RC31 Hawk GT

Offline ekpent

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Re: 79 CB750F bits found in oil pan.
« Reply #2 on: December 08, 2014, 10:41:02 AM »
Do you know if the engine was ever worked on or torn down before you. Who knows what can get dropped in while apart or working on it like that washer. Is that washer big enough to be a cylinder stud,nut deal for the head ? Looks kind of thick like an SOHC.

Offline thrutheframe

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Re: 79 CB750F bits found in oil pan.
« Reply #3 on: December 08, 2014, 12:50:54 PM »
Ekpent this engine has RTV poking out the sides everywhere you look. As far as it being a cylinder stud washer 10mm ID is probably too big.

It's certainly a mystery.
'74 cb 750 K4
'79 CB 650 http://forums.sohc4.net/index.php?topic=83981.0
'75 CB 360T
'90 RC31 Hawk GT

Offline thrutheframe

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Re: 79 CB750F bits found in oil pan.
« Reply #4 on: December 08, 2014, 06:29:20 PM »
Ek....  Hmmm you might be onto something.  Found that on eBay by searching "cb750f aluminum washer". They're calling it a "cylinder head sealing washer".
'74 cb 750 K4
'79 CB 650 http://forums.sohc4.net/index.php?topic=83981.0
'75 CB 360T
'90 RC31 Hawk GT

Online Don R

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Re: 79 CB750F bits found in oil pan.
« Reply #5 on: December 08, 2014, 10:10:09 PM »
 I wonder if a too long bolt bottomed out in a shallower threaded hole. Might have broken through and not even stripped out.
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Offline thrutheframe

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Re: 79 CB750F bits found in oil pan.
« Reply #6 on: December 09, 2014, 03:05:03 AM »

I wonder if a too long bolt bottomed out in a shallower threaded hole. Might have broken through and not even stripped out.

Or not enough thread on a shoulder?  I'll have it buttoned up enough to start again this weekend.  I'll definitely be listening with the stethoscope.
'74 cb 750 K4
'79 CB 650 http://forums.sohc4.net/index.php?topic=83981.0
'75 CB 360T
'90 RC31 Hawk GT