1973 Z1 Maui

Any updates on the Cam bearing failure ? I had the same failure today with in minutes of my first run. Bearings were purchased from Z1 industries, Installed consistent to the previous posts here and I have confirmed Oil is making it through all passages. 

 

ColonelBiscuit wrote:

Any updates on the Cam bearing failure ? I had the same failure today with in minutes of my first run. Bearings were purchased from Z1 industries, Installed consistent to the previous posts here and I have confirmed Oil is making it through all passages. 


 

When you say "the same failure" has the bearing turned ?
Did you check the clearance with plastigauge between the cam and new bearings ?

My Z1 project is neatly stored in the garage waiting for me to get back to it. Many things including my own hesitation have kept me from it. I put in a replacement oil pump, it’s assembled, ready for a test. As for plastigage and the cam bearings, it seems to be a moot point, there aren’t any over or under versions of the bearings. Other than checking for installation problems, what would one do if the clearance was a bit large or small. In my case there is sufficient clearance. 
Yes, my oring in the upper/lower case is there.
‘My bearings did not spin, they seized up and I did not force it. 
I’m going to give the new oil pump a try and if things go badly I may have to part out the project, I have a LOT of great parts including some rechrome work.
the bike has a title
lots of NOS stuff
beautiful body work, original stuff, repainted by a real master over on Oahu
stainless spokes
new fork tubes
carb chokes we’re renewed
gauges went to Marcel in the Netherlands for freshening up.
new repop exhaust
the list goes on.


 

Good to hear from you Maui, glad you haven’t given up on it

I’ve done quite a few complex projects at home and as part of my working life, I don’t often hit a wall, it has really stymied me. I’ll give it another chance. I’m unaccustomed to this.

Wookie58 - They don't seem to have turned, it was a "soft" stop while cranking and the bearings on the head seized to the cam. I plastigauged at initial assembly. Today I cleaned the head and applied compressed air to all the ports to confirm no clogs.

Am I missing anything on the cam bearing install; locator tab, lube at install, cap placement and Torque procedure?

I have a used exhaust cam and a different source of bearings ordered 

MauiZ1- What you noted is exactly the same as what I experienced and I feel your fears to have a repeat incident. Did you try a different source of bearings with your repairs?  

Thank you everyone for your help on this. 

ColonelBiscuit wrote:

Wookie58 - They don't seem to have turned, it was a "soft" stop while cranking and the bearings on the head seized to the cam. I plastigauged at initial assembly. Today I cleaned the head and applied compressed air to all the ports to confirm no clogs.

Am I missing anything on the cam bearing install; locator tab, lube at install, cap placement and Torque procedure?

I have a used exhaust cam and a different source of bearings ordered 

MauiZ1- What you noted is exactly the same as what I experienced and I feel your fears to have a repeat incident. Did you try a different source of bearings with your repairs?  

Thank you everyone for your help on this. 

As you will be aware from reading Maui's thread there where pages of suggestions he worked through !!! If the oil feed is good as you say and the clearance is in spec as you say (checked with plastigauge) then there is no reason for this (especially when cranking and not even running) Could it be a tensioner issue whereby the cam chain is "too tight" ???

I have tried  a stock tensioner and a heavy duty one. Engine turns nicely by hand. 

After hearing about some of these failures with the aftermarket bearings, I myself have decided to use only OEM bearings. I have a set of aftermarket bearings and quite frankly was afraid to use them on the last engine so I bought OEM. I have done many engines with new OEM bearings. Those bearings are only one size so if you have the original caps and the cams are true (using a dial indicator) and you have checked the diameters you should be good to go. I have never checked those bearing with plastigage and would only do so if I was not sure about the original caps or cams. I think the main problem has been those aftermarket bearing shells. Looking at them they don't look as nice as the OEM ones. 

I also think about how Maui's 73 is doing ,dont give up.

Cra-z1 wrote:

After hearing about some of these failures with the aftermarket bearings, I myself have decided to use only OEM bearings. I have a set of aftermarket bearings and quite frankly was afraid to use them on the last engine so I bought OEM. I have done many engines with new OEM bearings. Those bearings are only one size so if you have the original caps and the cams are true (using a dial indicator) and you have checked the diameters you should be good to go. I have never checked those bearing with plastigage and would only do so if I was not sure about the original caps or cams. I think the main problem has been those aftermarket bearing shells. Looking at them they don't look as nice as the OEM ones. 

I also think about how Maui's 73 is doing ,dont give up.

Only my opinion but for the time it takes it's worth it (I am a "belt and braces" kind of guy) yes the bearings are only available in one size but if the clearance is too small these failures are expensive. The bearing journals on the cams can be "ground" to get the correct clearance (should never be needed with OEM parts)

I have a cautious but optimistic update, my bike is running. I went back to the original bearings I found in the bike when I pulled it from the weeds. A friend cleaned up the exhaust cam on a lathe and I did some clean up on the rest. I never found any issue with the oiling system and I confirmed all my hard parts were well with in spec.