Author Topic: Which engine bearings to replace?  (Read 1050 times)

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Offline Nicolai

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Which engine bearings to replace?
« on: May 15, 2012, 02:42:49 AM »
Hi All

I have my engine apart at the moment and are replacing a bunch of stuff. However I am not sure about how to check if the different bearings need replacement. Are there any "guidelines" about which engine bearings that is most important to replace now that the case is open?

Nicolai
'77 CB500 K3

Offline Blasbo

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Re: Which engine bearings to replace?
« Reply #1 on: May 15, 2012, 04:35:55 AM »
I don't know if any are more critical than others but you measure the wear with plastigage. Put it on the bearing, re-assemble and torque to spec. Then dis-assemble and see how much the plastigage is "squished" and compare to the guide that comes with it. It's described pretty well in the manuals. I haven't done it, but it's next on the list.

Offline Rigid

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Re: Which engine bearings to replace?
« Reply #2 on: May 15, 2012, 04:42:29 AM »
They use colors to designate various clearances from the factory.  I have measured the OD of the crank journals with a micrometer and then compared it to stock.  The crank seldom wears but the bearings are designed to wear.  You can then replace the bearings matching the original colors and be reasonably certain the clearances are proper.
36 years of this stuff, here to help.

Offline nayto550

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Re: Which engine bearings to replace?
« Reply #3 on: May 15, 2012, 06:45:35 AM »
In addition to the crank main bearings, while you have the engine open it would be a good idea to check the transmission mainshaft bearing that is pressed into the case.  Roll it with your fingers, if there is any resistence or rough spots, replace it.  Also grab the inner race and try to move it up and down, if there is enough radial play that it can be felt, replace it.  Also do the same with the transmission countershaft bearing that is pressed into a carrier plate that mounts to the left side of the engine.

If you do have to replace one of these, make sure to ask specifically for non-sealed bearings, otherwise they will try to give you a sealed bearing.  I hate having to go back because I got the wrong part.  :P
« Last Edit: May 15, 2012, 06:47:08 AM by nayto550 »
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Offline lucky

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Re: Which engine bearings to replace?
« Reply #4 on: May 15, 2012, 08:24:04 AM »
REPLACE ALL of the bearings!!!

Some large ball bearings only cost $6.00 at the bearing supply house.
Do not buy them from Honda. They will be way overpriced.
Get grade 5 bearing or better. make sure the seals are the same or better.

Offline Cain74

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Re: Which engine bearings to replace?
« Reply #5 on: May 15, 2012, 08:40:53 AM »
Lucky - Do you have a link to the proper replacement bearings to buy?
(2) '73 750's Currently spread around the garage

Offline Nicolai

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Re: Which engine bearings to replace?
« Reply #6 on: May 15, 2012, 08:45:28 AM »
Yes it would be with some links to the proper bearings
'77 CB500 K3

Offline lucky

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Re: Which engine bearings to replace?
« Reply #7 on: May 15, 2012, 01:05:46 PM »
Lucky - Do you have a link to the proper replacement bearings to buy?

Just take them to the bearing supply and they can get you the correct bearings.
Many of those bearing in the Honda engine were made by one of the big bearing manufacturers anyway.

The crank main bearings is a separate issue.
Same with the rod bearings.