« previous next »
Pages: [1]   Go Down

Author Topic: Will loose studs cause head to leak?  (Read 1828 times)

0 Members and 1 Guest are viewing this topic.

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Will loose studs cause head to leak?
« on: August 24, 2012, 09:44:18 PM »
Hey Guys,

I'm rebuilding my head for the second time due to a solid leak on my right side. I'm thinking it could be from the front right cylinder stud being completely loose. So I might as well tighten (and check the rest!) to spec.

I looked in my manual and couldn't find the spec. I know 750's are 15-18 ft pounds (which seems REALLY high?).

Do you think having a backed out/super loose stud would cause a head gasket leak??

Thanks

Daniel
« Last Edit: August 25, 2012, 09:27:17 AM by danfr »
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline camelman

  • Man... Myth... Legend
  • Master
  • *****
  • Posts: 1,899
Re: CB350F Stud Torque?
« Reply #1 on: August 24, 2012, 11:48:24 PM »
14 to 16 if my memory is correct.  No books handy though.
Logged
1972 350f rider: sold
1972 350f/466f cafe: for sale
1977 CB400f cafe:sold
1975 CB400f rider: sold
1970 CB750 K0 complete bike: sold
2005 Triumph Sprint ST 1050 rider

We've got to cut it off... and then come down on rockets.  (quoted from: seven minutes of terror)

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: CB350F Stud Torque?
« Reply #2 on: August 25, 2012, 12:45:39 AM »
I found a thread that said 8 ft pounds for the 750. I decided to play it safe and torqued it down to 8. I know they are prone to stripping out.

Hopefully that is the only issue causing the leak. I'll check the cylinders with a straight edge tomorrow. I chased all the stud threading while I was at it. Fingers crossed!!

Thanks
Daniel
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: Will loose studs cause head to leak?
« Reply #3 on: August 25, 2012, 09:29:30 AM »
has anyone else had a head leak from loose studs?
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline KB02

  • Take it easy there, Sonny, I'm an
  • Old Timer
  • ******
  • Posts: 3,759
Re: Will loose studs cause head to leak?
« Reply #4 on: August 25, 2012, 09:59:56 AM »
That's what I am hoping has been my problem. I just re-torqued my head. Now I have to time the cam and button it all back u and go from there.
Logged
1978 CB750K Project
2000 Ducati ST2
...and a pedal bike

Join the AMA today!!

My project thread Part I: K8 Project "Parts Bike"
My project thread Part II: Finishing (yeah, right) touches on Project "Parts Bike"

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,715
Re: Will loose studs cause head to leak?
« Reply #5 on: August 25, 2012, 10:04:37 AM »
Some confusion here. Do yo mean a loose stud or a loose nut on the stud???

Also cam timing is set when you install the cam into the cylinder head with all of the correct marks lined up.
Setting your engine timing with the points is electrical timing.
Two separate things.
Logged

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: Will loose studs cause head to leak?
« Reply #6 on: August 25, 2012, 10:16:04 AM »
Quote from: KB02 on August 25, 2012, 09:59:56 AM
That's what I am hoping has been my problem. I just re-torqued my head. Now I have to time the cam and button it all back u and go from there.

Please let me know how it runs! Thanks

Quote
Some confusion here. Do yo mean a loose stud or a loose nut on the stud???

Also cam timing is set when you install the cam into the cylinder head with all of the correct marks lined up.
Setting your engine timing with the points is electrical timing.
Two separate things.

I mean loose stud into the lower case.

(I've rebuilt a few CB's and haven't had any issues set up the cam timing).
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,715
Re: Will loose studs cause head to leak?
« Reply #7 on: August 25, 2012, 10:27:18 AM »
Can you turn the stud with your fingers? Is it stripped?
Logged

Offline 70CB750

  • Labor omnia vincit improbus.
  • Really Old Timer ...
  • *******
  • Posts: 14,817
  • Northern Virginia
Re: Will loose studs cause head to leak?
« Reply #8 on: August 25, 2012, 10:31:35 AM »
Loose lips sink ships  ;D
Logged
Prokop
_______________
Pure Gas - find ethanol free gas station near you

I love it when parts come together.

Dorothy - my CB750
CB750K3F - The Red
Sidecar


CB900C

2006 KLR650

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: Will loose studs cause head to leak?
« Reply #9 on: August 25, 2012, 10:37:55 AM »
Quote from: lucky on August 25, 2012, 10:27:18 AM
Can you turn the stud with your fingers? Is it stripped?

I could turn it with my fingers. I tightened it up to 100 inch pounds. (8.5 foot pounds) and checked all the other studs to see if they were a minimum of 100 inch pounds.

Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,936
  • Bought her new 4/75
Re: Will loose studs cause head to leak?
« Reply #10 on: August 25, 2012, 10:40:01 AM »
Sure, but there are multiple other reasons for a head leak also.
Logged
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: Will loose studs cause head to leak?
« Reply #11 on: August 25, 2012, 10:53:22 AM »
Quote from: Jerry Rxman Griffin on August 25, 2012, 10:40:01 AM
Sure, but there are multiple other reasons for a head leak also.

I resurfaced the head and cut the valve seats. New head and base gasket.
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,936
  • Bought her new 4/75
Re: Will loose studs cause head to leak?
« Reply #12 on: August 25, 2012, 11:28:19 AM »
To name a few: Stud oil return seals and rubber pucks under cam towers. Cam tower studs leaking through/around threads.
Logged
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline danfr

  • Enthusiast
  • **
  • Posts: 211
    • Apollo Motorcycles
Re: Will loose studs cause head to leak?
« Reply #13 on: August 25, 2012, 11:42:28 AM »
Quote from: Jerry Rxman Griffin on August 25, 2012, 11:28:19 AM
To name a few: Stud oil return seals and rubber pucks under cam towers. Cam tower studs leaking through/around threads.

My bad, it's a 350f so no towers with troublesome pucks underneath.

I put in new rubber seals around the dowels between the head and cylinder. I'll wip it back together tonight and see what happens.
« Last Edit: August 25, 2012, 12:38:11 PM by danfr »
Logged
Apollo Motorcycles
-------------------------
71 Commando
74 CB750K
74 CB350F

Offline lucky

  • Really Old Timer ...
  • *******
  • Posts: 6,715
Re: Will loose studs cause head to leak?
« Reply #14 on: August 25, 2012, 11:58:58 AM »
Quote from: 70CB750 on August 25, 2012, 10:31:35 AM
Loose lips sink ships  ;D

What is it you are trying to say????
Logged

Offline Jerry Rxman Griffin aka MuthaF'er

  • This MuthaF'er is getting to be a
  • Really Old Timer ...
  • *******
  • Posts: 14,936
  • Bought her new 4/75
Re: Will loose studs cause head to leak?
« Reply #15 on: August 25, 2012, 03:23:18 PM »
Loose nuts sink head?!  ;D
Logged
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)
Pages: [1]   Go Up
« previous next »