Oil leaks

[GregMcN]

The good news is that having put my CB77 engine back together it runs, seems to have gears (though not taken on the road), electric start clutch now works as does kick start and no immediate problems with copper head gasket so on the face of it quite a bit of progress ............. but leaks like a sieve! So some questions.

The worst area unfortunately seems to be the cylinder base gasket.

When I assembled I did not use any kind of sealant with the gaskets as my view was that the gasket should do its job and the surfaces did not look too bad however maybe this is too optimistic for a 50+ year old bike. So some questions:

1. Do others normally use sealants in combination with gaskets and what do you recommend? - preferably available in the UK.
2. For the base gasket, as my bike has a 350 conversion with larger liners I had to modify a standard gasket although it looked OK clearly it is not working. Any other options to modifying a std gasket? Do you need the part of the gasket that goes between the cylinders adjacent to the cam chain as this is very thin with the larger liners?
3. Assuming I have to strip the engine again would the copper head gasket need to be annealed ...... it has only been run in the garage?
4. Any strategies to minimise leaks appreciated

Thanks Greg

[LOUD MOUSE]

Which base gasket did you use?
The one with 8 holes or the one with 9 holes?
What torque did you use?. ............lm

The good news is that having put my CB77 engine back together it runs, seems to have gears (though not taken on the road), electric start clutch now works as does kick start and no immediate problems with copper head gasket so on the face of it quite a bit of progress ............. but leaks like a sieve! So some questions.

The worst area unfortunately seems to be the cylinder base gasket.

When I assembled I did not use any kind of sealant with the gaskets as my view was that the gasket should do its job and the surfaces did not look too bad however maybe this is too optimistic for a 50+ year old bike. So some questions:

1. Do others normally use sealants in combination with gaskets and what do you recommend? - preferably available in the UK.
2. For the base gasket, as my bike has a 350 conversion with larger liners I had to modify a standard gasket although it looked OK clearly it is not working. Any other options to modifying a std gasket? Do you need the part of the gasket that goes between the cylinders adjacent to the cam chain as this is very thin with the larger liners?
3. Assuming I have to strip the engine again would the copper head gasket need to be annealed ...... it has only been run in the garage?
4. Any strategies to minimise leaks appreciated

Thanks Greg

[G-Man]

Greg

This is what LM is describing - two type of crankcase / barrel joint each with their own gasket .....






G

Which base gasket did you use?
The one with 8 holes or the one with 9 holes?
What torque did you use?. ............lm

The good news is that having put my CB77 engine back together it runs, seems to have gears (though not taken on the road), electric start clutch now works as does kick start and no immediate problems with copper head gasket so on the face of it quite a bit of progress ............. but leaks like a sieve! So some questions.

The worst area unfortunately seems to be the cylinder base gasket.

When I assembled I did not use any kind of sealant with the gaskets as my view was that the gasket should do its job and the surfaces did not look too bad however maybe this is too optimistic for a 50+ year old bike. So some questions:

1. Do others normally use sealants in combination with gaskets and what do you recommend? - preferably available in the UK.
2. For the base gasket, as my bike has a 350 conversion with larger liners I had to modify a standard gasket although it looked OK clearly it is not working. Any other options to modifying a std gasket? Do you need the part of the gasket that goes between the cylinders adjacent to the cam chain as this is very thin with the larger liners?
3. Assuming I have to strip the engine again would the copper head gasket need to be annealed ...... it has only been run in the garage?
4. Any strategies to minimise leaks appreciated

Thanks Greg

[GregMcN]

Hi lm/G man

To be honest I am not sure, I bought full gasket from eBay. If I had to guess I would say like the top one (8 hole) but not sure I remember the extended hole at the bottom RH corner.

Torque would have been as per clymer manual, about 2mkg but have probably tweaked a bit more since as also leaking a bit from head cover.

Greg

[LOUD MOUSE]

I torque to 22 FP with no problems.
Keep in mind nothing is flat like it was when new and assembled at HONDA.
I don't put any gasket sealant on any gaskets. ...................lm

Hi lm/G man

To be honest I am not sure, I bought full gasket from eBay. If I had to guess I would say like the top one (8 hole) but not sure I remember the extended hole at the bottom RH corner.

Torque would have been as per clymer manual, about 2mkg but have probably tweaked a bit more since as also leaking a bit from head cover.

Greg

[GregMcN]

I will try a higher torque though I think 22FP is right between what my 1/4 and 1/2inch torque wrenches cover.

What is the purpose of the extended hole in the bottom RH of Gman's top (8 hole) photo?

Greg

[G-Man]

Greg

The early (8 hole) and late (9 hole) engines have a completely different wat to distribute oil to the crank and top end. That hole by the stud does the same job (sort of) as the 9th hole in the later engines.

G

I will try a higher torque though I think 22FP is right between what my 1/4 and 1/2inch torque wrenches cover.

What is the purpose of the extended hole in the bottom RH of Gman's top (8 hole) photo?

Greg