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Rebuilt engine seized

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GregMcN
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Location: Richmond, North Yorkshire, UK

Post by GregMcN » Tue Jun 12, 2018 12:51 pm

Thanks Graham

When I get it stripped down again I will check for flatness and post some pictures. I did check the cases previously but I could of missed something and can not remember if I checked the barrel.

Greg

pemdoc65
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Post by pemdoc65 » Tue Jun 12, 2018 1:00 pm

I had a similar leak when I reassembled the engine for my CB72. I disassembled it again, and found that two of the cylinder studs were not fully threaded into the bottom case. It was causing those two head nuts to bottom out before reaching proper torque. I used a stud installer to screw the two studs further into the block, and it solved the problem.

GregMcN
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Joined: Tue Jul 04, 2017 3:34 pm
Location: Richmond, North Yorkshire, UK

Post by GregMcN » Tue Jun 12, 2018 3:42 pm

Thanks Pemdoc

I did check that none of the nuts were bottoming previously but I will recheck again when l reassemble.

GregMcN
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Joined: Tue Jul 04, 2017 3:34 pm
Location: Richmond, North Yorkshire, UK

Reason for leak

Post by GregMcN » Wed Jun 13, 2018 12:26 pm

On checking although the crankcase is flat there is a dip on the barrel adjacent to the 9th hole.


The pictures show flatness of the crankcase, and then the barrel either side of the hole and then the dip that is causing the problem. I have tried to measure and my best estimate is about 0.15mm at the edge , maybe a bit more over the hole.


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Greg

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G-Man
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Re: Reason for leak

Post by G-Man » Thu Jun 14, 2018 1:00 am

Hi Greg

Now we have a reason for the brass tube and the leak.

It will be necessary to heat the barrel to drop out the liners and then the bottom face can be skimmed flat. A pretty simple job which should sort the leak.

G

GregMcN wrote:On checking although the crankcase is flat there is a dip on the barrel adjacent to the 9th hole.


The pictures show flatness of the crankcase, and then the barrel either side of the hole and then the dip that is causing the problem. I have tried to measure and my best estimate is about 0.15mm at the edge , maybe a bit more over the hole.


Image

Image

Image

Image

Greg
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160
'66 Matchless 350 '67 CL77
'67 S90 '77 CB400F

GregMcN
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Joined: Tue Jul 04, 2017 3:34 pm
Location: Richmond, North Yorkshire, UK

Post by GregMcN » Tue Jun 19, 2018 2:47 am

Liners removed without problems, though undecided about skimming the existing barrel which has some fin damage or getting liners fitted to another barrel.

Image

Greg

GregMcN
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Joined: Tue Jul 04, 2017 3:34 pm
Location: Richmond, North Yorkshire, UK

Post by GregMcN » Tue Jun 19, 2018 3:24 am

When you replace the liners do you coat with anything. I think I saw krylon mention in a post but was not sure what that was.


Greg

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