1961 CB72 Project

G-Man · Post by **G-Man** » Tue Apr 07, 2015 4:08 pm

:-)

The motor on the left looks like a terminal case of red gasket cement......

G

jensey · Post by **jensey** » Wed Apr 08, 2015 1:05 am

Yes, I think the PO wanted to avoid using a new bottom gasket....

I have disassembled a few engines, CB72/77, C72/77 and CB450's. One thing I learned that the appearance of an engine says nothing about the state of the inner parts. A few years ago I disassembled a CB72'61 or '62 (forgot which year) which looked terrible from the outside. The inside however, was restored in a time that one bought a new crank instead of fixing the old one.

I wonder if you ever disassembled a CB72/77 '61 engine were no one was in before. Once I thought I had one, but seemed to have bin opened before.

G-Man · Post by **G-Man** » Wed Apr 08, 2015 1:23 am

Hi Jensen

Yes - it's a lottery. This bike has obviously been worked on as it had the 350 kit in it with a different head. I think that the crank was original and the gearbox internals, but it had definitely been apart.

I bought a second '61 motor and that had odd pistons and many wrong parts. I think it had a 305 crank etc.

I have 1960 C72 and C77 to dismantle both of which might be untouched at the bottom end. I have not dismantled my 1962 C72 yet but I think that is the top candidate for never being apart.

The '63 motor I showed in my last post has a very fresh looking 305 crank in it and the primary chain feels tight so I am very hopeful for that one.

The 14mm bush in the '61 engine interested me. It seems to have survived better than the later ones. Did your '61 motors have that?

Not sure if my '64 CB77 motor is untouched by humans but has certainly interacted with the British weather.....

It looks a little different now. :-)

G

deafanddiabetic · Post by **deafanddiabetic** » Wed Apr 08, 2015 1:55 pm

G-Man, do you have any advice for cleaning off the gasket surfaces? Have some tacky crap still left on mine. My go-to is usually mild sandpaper, a box cutter blade and Simple Green, but before I put the cases back together, I want this baby to shine.

Seadog · Post by **Seadog** » Wed Apr 08, 2015 3:03 pm

G-Man wrote:
Tonight I was going to put the selector drum and forks in the case but just noticed another gear with damage.

G

I feel like an idiot, but I've been staring at this photo trying to see where the damaged gear is and I just cannot find it. Could you point it out?

Thanks for your detailed posts. You go far beyond what most of us are capable of.

G-Man · Post by **G-Man** » Wed Apr 08, 2015 3:26 pm

Seadog

Here you go. The damage is on the surface of the gear teeth. This is not the worst gear but the pitting here could eventually turn into cracks from which the gear tooth would break up.

G

Seadog wrote:
G-Man wrote:

G
I feel like an idiot, but I've been staring at this photo trying to see where the damaged gear is and I just find it. Could you point it out?

Thanks for your detailed posts. You go far beyond what most of us are capable of.

G-Man · Post by **G-Man** » Wed Apr 08, 2015 3:30 pm

D&D

I usually go for solvent and wire wool if it's just sticky stuff. The box cutter blade works great if you are careful. If there are burrs and dings I wrap fine wet/dry paper round a flat aluminium bar ( 2 inc x 1 inch ) and sand gently using the rest of the case as a guide. These cases have been aqua-blasted which is glass beads is water and detergent.

G

deafanddiabetic wrote:G-Man, do you have any advice for cleaning off the gasket surfaces? Have some tacky crap still left on mine. My go-to is usually mild sandpaper, a box cutter blade and Simple Green, but before I put the cases back together, I want this baby to shine.