Topic: 1971 CB500 Engine Crack

[mardimus]

Any thoughts on how to fix the below crack.  The engine is a 1971 CB500 and it is going to be rebuilt.  I did some research but nothing real concrete as to how to fix or should I replace. Thanks for taking the time to look.   

[pangloss]

Well it LOOKs to be Non "Structural" in that it's only into the ignition cavity..

 No sign of oil or crankcase penetration..?? 

If So it could probably be patched..

[bryanj]

If you have the piece(s) epoxy (JB) or tig weld. If not a used lower half

[dave500]

the cases are matched/machined pairs,they should kept as pairs only.

[faux fiddy]

the cases are matched/machined pairs,they should kept as pairs only.

+1 I say, or re machine the bottom to match.

I'd say weld or start with  another off the classifieds. Actually jb can work but clean meticulously and rough it up.

[bryanj]

Sorry peeps, lower half in UK means everything below the base gasket!! Of course cases are matched pairs and if you get a complete bottom end there will be no need to sort out shells.

Sorry again for confusion

[mardimus]

Thanks to all who posted.  I thought about patching it but it seems it would be tough as the pieces are no where to be found.  The other worry I have is the screw thread for the case cover.  You can see it in the pic.  I looked around for a bottom half but also read that ,yes, a bottom half may not match up as they are machined in pairs.  How would one patch this? Anyone have a link to a write up.  I have a friend who can weld but want to read up on it before I make a decision.  Thanks, again. 

[Mo]

Could you perhaps make a "cast" out of JB weld and shape it do the fracture?

[mardimus]

That is a great idea.  I think I might look into that.

Could you perhaps make a "cast" out of JB weld and shape it do the fracture?

[CB750F2]

If you could locate a thrashed bottom case you could cut a piece out of it, shape your case so that it fits and then tig  it in. Pat