Author Topic: Plastigage? and main bearings.  (Read 1575 times)

Offline Trigger

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Re: Plastigage? and main bearings.
« Reply #15 on: August 13, 2022, 07:44:38 PM »
Crank journal wear can be felt with the finger nail as, the shape of the shell. The centre part of the journal never touches the shell so, the worn part is always the two sides of the journal. The only time the centre part has any wear is, if the oil has contaminates in it. 
Just think of a crank rotating at 5,000 rpm for 40,000 miles, you will find some sort of wear to the running part of the journal and shell.  ;) 

Offline Seabeowner

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Re: Plastigage? and main bearings.
« Reply #16 on: August 15, 2022, 07:21:27 PM »
Rough calculation: Maybe about 250 million turns.
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange
1978  CB550K     Excel Black

Offline SumpMagnet

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Re: Plastigage? and main bearings.
« Reply #17 on: August 15, 2022, 08:54:51 PM »
so it's check clearances with plastigage and existing shells.
Work out if clearances are right ( need to dig out the digital manual )
Then buy shells based on what I find.

If the other journals are in spec...replace the one bad with a new Green shell.

If meaqsurements do not sit within tolernaces...work out what I might need. I know proper clearances are critical for these bearings, as the oil is pressyure fed into the middle...and excessive tolerances won't maintain the oil film needed to lube the surfaces. As will over tight ones.
CB750F2 - in pieces
CB900F Hornet - the daily transport

Offline Trigger

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Re: Plastigage? and main bearings.
« Reply #18 on: August 16, 2022, 06:58:07 AM »
so it's check clearances with plastigage and existing shells.
Work out if clearances are right ( need to dig out the digital manual )
Then buy shells based on what I find.

If the other journals are in spec...replace the one bad with a new Green shell.

If meaqsurements do not sit within tolernaces...work out what I might need. I know proper clearances are critical for these bearings, as the oil is pressyure fed into the middle...and excessive tolerances won't maintain the oil film needed to lube the surfaces. As will over tight ones.

If you need to replace any shells, they must be done in pairs  ;)

Offline SumpMagnet

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Re: Plastigage? and main bearings.
« Reply #19 on: August 16, 2022, 06:40:58 PM »
yup. That was the one bit I did know :)

Shopping for plastigage now....so hopefully I can do some measuring this weekend.
CB750F2 - in pieces
CB900F Hornet - the daily transport

 

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