1964 Honda Dream CA78 Rebuild-storation

[Bob750]

Thank you, gentlemen, for your thoughts and advice.

Graham, I may try your cable modification. Will the inner metal jacket cut well enough with a pair of diagonal cutters (dykes)? Does this happen a lot? Should I simply get a NOS cable from Nick instead of a repro?

You are correct, LM; the nut in question is the one that came with the bike at that location. I did order and install a new special crush washer (aluminum, similar to the oil drain seal). But even though I saw the different image of the nut in the drawing, I thought it may just be one of those "it doesn't look like that in real life" situations. I suppose I'll have to look for a special nut. Is blind nut another term for cap nut? I'll be looking for another "WASHER A, 6.5MM 90481-250-000" and a "NUT, SEALING, 6MM 90241-259-000" to fix that. I suppose a drop of thread sealant on the tip of the stud wouldn't hurt either. What is the point of this arrangement anyway, from an engineering standpoint? Why have a hole in the bottom of the case that we have to plug with a washer and nut?

As for the oil pump seep, I think I know the reason: The flange of the screen that sits between the gaskets has a crack running out from near the base of the screen wall to near the point above the drain plug. It was so fine I thought the gaskets would seal it (it wasn't leaking before), and I suppose in time they possibly could, but I think I'll take that down and try to replace the cracked screen (if I can find one) or use some gasket sealing material to fill in the crack. What's the possibility of running with out the screen? Wasn't it later deleted?

And as for my head gasket seep, Graham, I guess I'm perplexed if that's case (cap nut bottoming on stud), since the bike was running with no leaks when I took it apart to repair the transmission. The studs stayed in, and I believe I cleaned and reused the cap nuts, and I installed NOS copper washers which were hard to find even without the zinc plating which would be more correct. I suppose, in the 5 or 6 months the completed engine has been sitting on the shelf waiting for the frame, that some gasket compression could have occurred and simply backing off and re-torquing the head nuts could seal the deal? What do you all torque the top nuts and side nuts (next to spark plug) to? I think I went to 16.5 lb-ft on the tops. I can't recall what I did on the sides. Also has anyone ever double-washered in the case of a long stud bottoming in a cap nut? I have 2 more of those washers.

Thanks again for the help. Today, I'll fire it up briefly to check the movement of the shifter and transmission, just to be sure it works properly when running, before possibly lowering the engine. I can still adjust rpm by tugging on the throttle cable jacket where it comes out of the frame, but I suppose I shouldn't try to ride it around that way... ;-)

I also noticed the missing blind nut but here in the states we had/have aluminum washers at that location.
Looks like he may have the aluminum washer installed but incorrect type nut. .....lm

Bob

You might have the same problem that Sara had with her CB77. The dowels on the front cylinder studs may be bottoming out and stopping the gasket compressing. This may be because the head or barrel has been skimmed at some time. Shortening the dowels might help.

Your little M6 bolt next to the oil pump should have a blind nut with a copper washer underneath. You'll find that in your meticulous pars system. Not sure about the other drips on the oil pump. You may have to wipe that down and watch the area as you run the motor again.

As for the carb - you may be able to peel a few turns of the outer cable to effectively give you more inner. Pull off the ferrule. Carefully cut through the plastic outer and you will see that the cable is just a long coil of square section wire. Cut some off and re-seat the ferrule.

Looking good!


G

[G-Man]

Thank you, gentlemen, for your thoughts and advice.

Graham, I may try your cable modification. Will the inner metal jacket cut well enough with a pair of diagonal cutters (dykes)? Does this happen a lot? Should I simply get a NOS cable from Nick instead of a repro?

You are correct, LM; the nut in question is the one that came with the bike at that location. I did order and install a new special crush washer (aluminum, similar to the oil drain seal). But even though I saw the different image of the nut in the drawing, I thought it may just be one of those "it doesn't look like that in real life" situations. I suppose I'll have to look for a special nut. Is blind nut another term for cap nut? I'll be looking for another "WASHER A, 6.5MM 90481-250-000" and a "NUT, SEALING, 6MM 90241-259-000" to fix that. I suppose a drop of thread sealant on the tip of the stud wouldn't hurt either. What is the point of this arrangement anyway, from an engineering standpoint? Why have a hole in the bottom of the case that we have to plug with a washer and nut?

As for the oil pump seep, I think I know the reason: The flange of the screen that sits between the gaskets has a crack running out from near the base of the screen wall to near the point above the drain plug. It was so fine I thought the gaskets would seal it (it wasn't leaking before), and I suppose in time they possibly could, but I think I'll take that down and try to replace the cracked screen (if I can find one) or use some gasket sealing material to fill in the crack. What's the possibility of running with out the screen? Wasn't it later deleted?

And as for my head gasket seep, Graham, I guess I'm perplexed if that's case (cap nut bottoming on stud), since the bike was running with no leaks when I took it apart to repair the transmission. The studs stayed in, and I believe I cleaned and reused the cap nuts, and I installed NOS copper washers which were hard to find even without the zinc plating which would be more correct. I suppose, in the 5 or 6 months the completed engine has been sitting on the shelf waiting for the frame, that some gasket compression could have occurred and simply backing off and re-torquing the head nuts could seal the deal? What do you all torque the top nuts and side nuts (next to spark plug) to? I think I went to 16.5 lb-ft on the tops. I can't recall what I did on the sides. Also has anyone ever double-washered in the case of a long stud bottoming in a cap nut? I have 2 more of those washers.

Thanks again for the help. Today, I'll fire it up briefly to check the movement of the shifter and transmission, just to be sure it works properly when running, before possibly lowering the engine. I can still adjust rpm by tugging on the throttle cable jacket where it comes out of the frame, but I suppose I shouldn't try to ride it around that way... ;-)

I also noticed the missing blind nut but here in the states we had/have aluminum washers at that location.
Looks like he may have the aluminum washer installed but incorrect type nut. .....lm

Bob

You might have the same problem that Sara had with her CB77. The dowels on the front cylinder studs may be bottoming out and stopping the gasket compressing. This may be because the head or barrel has been skimmed at some time. Shortening the dowels might help.

Your little M6 bolt next to the oil pump should have a blind nut with a copper washer underneath. You'll find that in your meticulous pars system. Not sure about the other drips on the oil pump. You may have to wipe that down and watch the area as you run the motor again.

As for the carb - you may be able to peel a few turns of the outer cable to effectively give you more inner. Pull off the ferrule. Carefully cut through the plastic outer and you will see that the cable is just a long coil of square section wire. Cut some off and re-seat the ferrule.

Looking good!


G

LM is correct, that M6 sealing washer is aluminium, not copper. I'm just not a big fan of aluminium washers.....

The nut just like a tall hexagon with a flat top - see picture below.


The nuts bottoming out could be the problem with the head leak but Sara's problem was different. The 'knock pins' between head an barrel were effectively too long, preventing head an barrel closing on the gasket. To test you might leave out the gasket and bolt the head up lightly. If you can see daylight the knock pins are too long....

As for the cable - yes you could use cutters but I have used a mini hacksaw (very carefully). Cutters are probably safer on second thoughts. Yes you can just by a genuine NOS cable and that should also fix the issue.

Don't forget to have fun..... !


G

[Bob750]

Okay, so searching the web for those parts is sad making. Someone on eBay is selling the wrong part as the special nut. The only place I can find the strainer is CMSNL, along with the nut, but with shipping the order is over $60. Gonna try the wanted thread before going overseas...

Hey, G-Man, you wanna sell me the nut that's in your photo??

[G-Man]

Bob

I'll send you the nut and strainer for nothing but you'll have to wait until the weekend before I can mail them. I'm out and about the next couple of days...

Your bike is a bit of an inspiration. I have a wreck of a white Dream and I didn't think I wanted a white one but you have changed my mind with your beautiful project.

G

[Bob750]

Graham, you are a true gentleman!

I had just sent an inquiry to HondaNuts when your reply came. Visit http://www.hondanuts.com/nos.html. Click on their NOS link, and search that page. They supposedly have the nut, the washer, and the strainer. If they don't actually have them, I'll take you up on your very kind offer!

Cheers!

Bob

I'll send you the nut and strainer for nothing but you'll have to wait until the weekend before I can mail them. I'm out and about the next couple of days...

Your bike is a bit of an inspiration. I have a wreck of a white Dream and I didn't think I wanted a white one but you have changed my mind with your beautiful project.

G

[48lesco]

Bob - Absolutely beautiful work, I love the attention to detail!

Couple of thoughts

Head gasket leak: I looked back through your reassembly pics and it appears you didn't use an OEM head gasket. That's a crap shoot. The metal ring, and surrounding gasket material have to work with those o-rings pretty precisely for a good seal everywhere. Call me if you want to go with an OEM gasket. Also did you make sure the cylinder liners were flush with the block? If they are proud by more than a couple thousandths, the gasket and o-rings may not seal. Also, as G said, make sure the knock pins and acorns aren't bottoming. You could just try an extra couple foot-lbs too.

Oil pump leak: I think the gasket sealer in the crack is a good idea. DON'T run without the screen though. The screen and both gaskets are what determine the clearance between the pump and crank gears.

Throttle cable: I didn't see it where I would have expected it in the pictures but maybe you hadn't installed it yet... Before you blame the cable, make sure it's routed properly, then blame the cable.
-48

[G-Man]

Graham, you are a true gentleman!

I had just sent an inquiry to HondaNuts when your reply came. Visit http://www.hondanuts.com/nos.html. Click on their NOS link, and search that page. They supposedly have the nut, the washer, and the strainer. If they don't actually have them, I'll take you up on your very kind offer!

Cheers!

Bob

I'll send you the nut and strainer for nothing but you'll have to wait until the weekend before I can mail them. I'm out and about the next couple of days...

Your bike is a bit of an inspiration. I have a wreck of a white Dream and I didn't think I wanted a white one but you have changed my mind with your beautiful project.

G

Bob

Let me know and I'll put them ready.

G