Author Topic: Checking bearing clearance on CB 750..?..?  (Read 1229 times)

0 Members and 1 Guest are viewing this topic.

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Checking bearing clearance on CB 750..?..?
« on: June 25, 2009, 07:59:56 PM »
This is a bit like a poll, looking for answers/ thoughts,  from those who have used plastiguage and replaced at least one set of CB 750 bearings


Guy has a 30 yr old oneowner 750, say 30,000 miles, running fine.

It has a trans problem, and cases are coming out & getting split, to fix problem. Top end is staying on.

Not under a stiff time constraint, motor is apart a few days..

Upon inspection, berings & crank appear fine, look quite good.

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Hers is the Q, would you;
 put it back together cuz it looks good..?

 or..

 plastiguage it and check, seeing as it is already apart?
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 bucky katt

  • Old Timer
  • ******
  • Posts: 4,564
  • i am a pastafarian!
    • facebook
Re: Checking bearing clearance on CB 750..?..?
« Reply #1 on: June 25, 2009, 08:04:43 PM »
check it, no question about it.
Of all God's creatures there is only one that cannot be made the slave of the lash. That one is the cat. If man could be crossed with the cat it would improve man, but it would deteriorate the cat.
Mark Twain - Notebook, 1894

Offline mystic_1

  • Really Old Timer ...
  • *******
  • Posts: 6,071
  • 1970 CB750K
Re: Checking bearing clearance on CB 750..?..?
« Reply #2 on: June 25, 2009, 08:27:45 PM »
Do it.  If you don't, you'll forever wonder.  Only takes a little while.  Check the rods too.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0

Offline MRieck

  • Really Old Timer ...
  • *******
  • Posts: 10,565
  • Big ideas....
Re: Checking bearing clearance on CB 750..?..?
« Reply #3 on: June 25, 2009, 08:32:11 PM »
If the engine was running fine and the bearings look good why screw around with it?  ::)
Owner of the "Million Dollar CB"

Offline HavocTurbo

  • Angry little bastard of an
  • Old Timer
  • ******
  • Posts: 3,739
  • Can you tell?
Re: Checking bearing clearance on CB 750..?..?
« Reply #4 on: June 25, 2009, 09:53:54 PM »
If the engine was running fine and the bearings look good why screw around with it?  ::)

See that's what puts me on the fence.

I say go with your gut and see what happens. It's a tough choice for sure.
'48 HD Panhead - Exxon Valdez
'78 CB550K - Fokker CB.3
'78 Honda CB750K - Mavrik
'80 Yamaha XS850G - Kanibalistik
09 XL883L - No Name

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,923
  • Bought her new 4/75
Re: Checking bearing clearance on CB 750..?..?
« Reply #5 on: June 26, 2009, 10:13:58 PM »
6 of 1 or a half dozen of the other.

I say it all depends on how much cash you're putting into it.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: Checking bearing clearance on CB 750..?..?
« Reply #6 on: June 26, 2009, 10:19:19 PM »
They are not  really putting any cash into it, merely opened it up to change one part.. Motor/ lower end had never  previously been opened up.
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 CB750F2

  • Hot Shot
  • ***
  • Posts: 645
  • Pat's first Honda 750 F2
Re: Checking bearing clearance on CB 750..?..?
« Reply #7 on: June 26, 2009, 10:58:32 PM »
I would check the big end rod clearances but not the mains. The big ends are subjected to more abuse than the mains. Just my opinion, Pat
Regards
Pat from Australia

Offline bryanj

  • Really Old Timer ...
  • *******
  • Posts: 14,044
  • CB500 Number 1000036
Re: Checking bearing clearance on CB 750..?..?
« Reply #8 on: June 27, 2009, 05:31:58 AM »
If the shells are even grey and clean, bolt it back up with out silicone everywhere
Semi Geriatric ex-Honda mechanic and MOT tester (UK version of annual inspection). Garage full of "projects" mostly 500/4 from pre 73 (no road tax in UK).

Remember "Its always in the last place you look" COURSE IT IS YOU STOP LOOKIN THEN!

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,923
  • Bought her new 4/75
Re: Checking bearing clearance on CB 750..?..?
« Reply #9 on: June 27, 2009, 09:52:57 AM »
They are not  really putting any cash into it, merely opened it up to change one part.. Motor/ lower end had never  previously been opened up.

Throw her back together then rather than open up a can of worms.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline 754

  • Really Old Timer ...
  • *******
  • Posts: 29,058
Re: Checking bearing clearance on CB 750..?..?
« Reply #10 on: June 27, 2009, 10:01:57 AM »
Can is already open, and you can see the worms, and you have looked at the worm, and they looked good.. but do you want to measure the worms?.. to see if they will last a few months.. or another decade..

NOTE** I was referring to checking the exposed mains, not taking off the rods caps, in this topic.

 Some folks check their compression, just because
 Why? probably because they want some indication of engine condition.. I am thinking..
« Last Edit: June 27, 2009, 01:31:28 PM by 754 »
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 ofreen

  • Old Timer
  • ******
  • Posts: 4,034
Re: Checking bearing clearance on CB 750..?..?
« Reply #11 on: June 27, 2009, 12:31:34 PM »
If the engine was running fine and the bearings look good why screw around with it?  ::)

Agreed.  The only reason I'd do it is out of scientific curiousity, if I thought I was going to measure again in another 30,000.
Greg
'75 CB750F

"I would rather have questions I cannot answer than answers I cannot question." - Dr. Wei-Hock Soon

Offline mystic_1

  • Really Old Timer ...
  • *******
  • Posts: 6,071
  • 1970 CB750K
Re: Checking bearing clearance on CB 750..?..?
« Reply #12 on: June 27, 2009, 02:02:38 PM »
The only reason I'd do it is out of scientific curiousity, if I thought I was going to measure again in another 30,000.


This is exactly why I'd do it.  Knowing is good, and this measurement is so quick and easy to take when the motor is at this stage.

mystic_1
"A ship in harbor is safe, but that is not what ships are built for."
- John Augustus Shedd

My build thread:  http://forums.sohc4.net/index.php?topic=68952.0