1961 CB72 Project

jensey · Post by **jensey** » Tue Mar 17, 2015 3:06 pm

Hi Graham,

This is one of the most informative threads I've ever come across.
Every morning or afternoon I'm looking if there's an update yet.

Thanks for shearing the gained knowledge and the time to write it down !

Jensen

G-Man · Post by **G-Man** » Tue Mar 17, 2015 3:13 pm

After doing those plugs again it was time to put the flywheels back in the ultrasonic bath to shake out any aluminium particles that got shaved off.

Just before I did that I had another look at the main bearing outer races and discovered that the small oil holes which transfer a feed to the big ends were still blocked with black sludge despite several trips to the cleaning bath.

I poked a pipe cleaner in where I could and pushed out some globs of nasty black stuff.

That didn't do a lot of good so i dropped the bearings in beaker of alcohol to soften things up a bit more and had another poke around.

Even more muck oozed out so more soaking and more poking with the pipe cleaner was the order of the day.

In the end the bearings went in the hot bath with the other parts for a final clean up. These are the jets which direct oil to the big end and they are critical to the long and healthy life of the hard-worked big end.

The bearing fits up to the inner flywheel and that ring fits inside the centrifugal feed to the big end bearing.

The oil gallery to the big end is the hole circled in red. This is the hole that has the aluminium bung at the outer end. I'm quite pleased that the crank didn't go back together with all of that dirt in such critical oil ways. It would have been a short first ride otherwise.

Here are the cleaned parts, yet again, on their way to final assembly......

I'm looking forward to getting on to the next job.... :-)

G

G-Man · Post by **G-Man** » Tue Mar 17, 2015 3:21 pm

Jensen

Thank you for your kind comments. I'm very happy to share this stuff. Like you said in your CB450 test article, it is the comments and feedback that give us the energy to share. There are many more photographs than can be shown here but there are no secrets. It is clear that lubrication plays a very big part in the running of these engines and the crank appears to be a better centrifuge than the oil filter.....

G

jensey wrote:Hi Graham,

This is one of the most informative threads I've ever come across.
Every morning or afternoon I'm looking if there's an update yet.

Thanks for shearing the gained knowledge and the time to write it down !

Jensen

Tim Miller · Post by **Tim Miller** » Tue Mar 17, 2015 3:42 pm

G,
As for the alloy plugs I make them with .001 interference fit and install with Loctite 609.
After my first crank rebuild and seeing all the crap and wear I will always use a real filter and synthetic oil desiged for motorcycles with wet clutch / gears.
It's great seeing a real rebuilt engine being documented.

Keep up the good work,
Tim

jensey · Post by **jensey** » Tue Mar 17, 2015 3:59 pm

Hi Graham,

Yes, it's the contributions that keeps one going.

If the crank is within specifications, I flush the crank over a period of weeks, sometime months, interspersed with ultrasonic baths. This is a CB450K0 crank in solution.

Fluids I use:

petrol, thinner, alcohol, degreaser and sometimes more aggressive stuff.

In the bottle, all the stuff from one crank is gathered. This crank only had around 1500 miles on it, no more. The crank was within spec, so no pressing needed (this time).

I do this with all my cranks, sometimes it takes just a few days, sometimes it takes months to break up layer after layer. Especially when the PO's used oil with Zinc Diakyl Dithiophosphates, these layers can be very difficult to solve. The pump is a high pressure gear pump, driven by a 24V motor. I press the tubes into the oil feeds. In the beginning the pump is sucking the fluids via the big-end into the pump untill the bigger chunks are gone, then I switch the tubes and press the fluids through the oil feeds for days.

When possible, I clean the passages mechanically first (pipe rag), also the centrifugal area is cleaned mechanical (this is possible with the CB450 K0 cranks).

G-Man · Post by **G-Man** » Tue Mar 17, 2015 4:07 pm

Tim

Jerry's advice was the same. I did find more than 0.005 difference between the two galleries. I should have measured both, obviously..... :-) I wasn't really sure what the process was. Whether is was a simple interference fit or if it was peened in place...

Yes - after finding all this mess stuck in the crank and bearings, I'm heading that way. You need a really sharp tool to get that stuff out of the centrifuge in the crank. I cannot think what might happen if that came unstuck when bathed in hot oil.

I'm in no hurry. just enjoying the journey.

G

Tim Miller wrote:G,
As for the alloy plugs I make them with .001 interference fit and install with Loctite 609.
After my first crank rebuild and seeing all the crap and wear I will always use a real filter and synthetic oil desiged for motorcycles with wet clutch / gears.
It's great seeing a real rebuilt engine being documented.

Keep up the good work,
Tim

G-Man · Post by **G-Man** » Tue Mar 17, 2015 4:10 pm

Jensen

That requires some patience. Have you ever had the sludge analysed. I've often wondered how much of that stuff is actually decomposed oil.....

G

jensey wrote:Hi Graham,

Yes, it's the contributions that keeps one going.

If the crank is within specifications, I flush the crank over a period of weeks, sometime months, interspersed with ultrasonic baths. This is a CB450K0 crank in solution.

Fluids I use:

petrol, thinner, alcohol, degreaser and sometimes more aggressive stuff.
In the bottle, all the stuff from the crank is gathered. This crank only had around 1500 miles on it, no more. The crank was within spec, so no pressing needed (this time).

I do this with all my cranks, sometimes it takes just a few days, sometimes it takes months to break up layer after layer. Especially when the PO's used oil with Zinc Diakyl Dithiophosphates, these layers can be very difficult to solve.