1961 CB72 Project

[G-Man]

Tim

Thanks! Dave the "Crank Man" has already suggested that we do that. I'm just getting ready with a couple of cranks for him to strip and clean up for me. If possible I would like to put together a good early crank for this bike.

Do you have any thoughts about the shield on the 020 bearing going on the inside? Perhaps early engines with the open bearing had a tendency to unseat the oil seal? I'm still perplexed why the shield doesn't go on the outside.... If the splash feed was efficient enough to give the seal a hard time you then wonder about the mods to the oil feed on the later engines. I suppose I have the luxury of hindsight but I like to understand the engineering.

G

[Tim Miller]

Graham

My first 61 cb72 that I rebuilt #1539 had the 010 bearing. So, it's possible your bearing was replaced at some point?
If you flip your top engine case over and lay your crank down on locating pins you will see that the oil galley feeds between the right bearing and oil seal. There's about 1.75mm gap between the bearing and oil seal for oil to flow (This is for the early oiling system only!). I Believe the shielded (020)was introduced to hold more oil in the bearing.
I have rebuilt 10 plus engines ( with later oiling system/ with no oil feed) using both 010&020 bearings with no problems. I guess there's enough oil flying around to keep them alive.

Tim

[G-Man]

Tim

Thanks for putting me straight. I was looking at the differences between two bearings rather than the cases.

Every day is a school day, as my old friend used to say.....



I just have to work out why the little hole in my roller bearing outer doesn't seem to line up, now. I'm getting there. Slowly......


G

[LOUD MOUSE]

Are the index lines on the other side of the bearing?. ........lm

Tim

Thanks for putting me straight. I was looking at the differences between two bearings rather than the cases.

Every day is a school day, as my old friend used to say.....



I just have to work out why the little hole in my roller bearing outer doesn't seem to line up, now. I'm getting there. Slowly......


G

[G-Man]

Tim

The bike if you remember my 'before' pictures had extensive surgery after being crashed (I think). It was fitted with later wheels and forks and, at some stage, gained a 350 kit. It wouldn't surprise me if some of the bottom end was changed at that time. It certainly had a later head and cam fitted. Pretty sure it sat idle from '73 but there was plenty of time from '61 to 73 for it to be re-worked.

G

Graham

My first 61 cb72 that I rebuilt #1539 had the 010 bearing. So, it's possible your bearing was replaced at some point?
If you flip your top engine case over and lay your crank down on locating pins you will see that the oil galley feeds between the right bearing and oil seal. There's about 1.75mm gap between the bearing and oil seal for oil to flow (This is for the early oiling system only!). I Believe the shielded (020)was introduced to hold more oil in the bearing.
I have rebuilt 10 plus engines ( with later oiling system/ with no oil feed) using both 010&020 bearings with no problems. I guess there's enough oil flying around to keep them alive.

Tim

[G-Man]

LM

No they are on the side with the other markings. Just a bad photo from that respect.

G

Are the index lines on the other side of the bearing?. ........lm

Tim

Thanks for putting me straight. I was looking at the differences between two bearings rather than the cases.




G

[G-Man]

Here's something that added to my confusion. The top photo is the 1961 CB72 crankcase with the oil hole outboard of the knock pin.



And here is the later type with the oil hole (which matches the hole in the roller bearing) inboard of the knock pin.




Honda weren't short of ideas on getting oil to that bearing....

G