Author Topic: HELP! bad crank from cb750k 1977  (Read 786 times)

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Offline la ca fe

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HELP! bad crank from cb750k 1977
« on: April 04, 2019, 07:31:59 PM »
I have a '77 k motor with a bad crank.
Does anyone know if other cranks from other year cb750 's will work or are they year specific?

Do I need a replacement crank from a '77k only?
1973 cb750
1977 cb750k
1975 cb750 f

Offline 754

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Re: HELP! bad crank from cb750k 1977
« Reply #1 on: April 04, 2019, 08:31:46 PM »
70 to 78 should work, except for Automatics.
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

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It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Tracksnblades1

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Re: HELP! bad crank from cb750k 1977
« Reply #2 on: April 04, 2019, 08:49:29 PM »
It's a selective process. The main bearing journals can have different size bearings from the factory. Same with the four rods. Read your codes on crank and case.
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Offline Tracksnblades1

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Re: HELP! bad crank from cb750k 1977
« Reply #3 on: April 04, 2019, 08:53:31 PM »
This may help....
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Offline 754

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Re: HELP! bad crank from cb750k 1977
« Reply #4 on: April 04, 2019, 09:02:40 PM »
They all fit all the years, put the crank markings and case markings together and select your bearings.
 Some run all one color and clearance be damned.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Online Don R

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Re: HELP! bad crank from cb750k 1977
« Reply #5 on: April 06, 2019, 12:08:37 AM »
 A friend of mine has been building and rebuilding 750's for years. He buys green bearings for everything and checks clearance with plastigauge. Rarely makes an adjustment. That said it can't hurt to read the sizes since these are all over 40 years old.
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Offline la ca fe

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Re: HELP! bad crank from cb750k 1977
« Reply #6 on: April 16, 2019, 08:29:08 AM »
Thanks for the replies everyone,
I found a motor that is the same year that I am going to take the crank out of to use.
I wonder if the bearings will work? Same year.

1973 cb750
1977 cb750k
1975 cb750 f

Offline 754

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Re: HELP! bad crank from cb750k 1977
« Reply #7 on: April 16, 2019, 08:55:44 AM »
Year has nothing to do with it, read the codes on the case, both sets.
 If the same, then you might be able to swap bearings .
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline la ca fe

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Re: HELP! bad crank from cb750k 1977
« Reply #8 on: April 16, 2019, 09:20:48 AM »
Thanks!
1973 cb750
1977 cb750k
1975 cb750 f