« previous next »
Pages: [1]   Go Down

Author Topic: You're gonna hate this  (Read 1152 times)

0 Members and 1 Guest are viewing this topic.

Offline JimZ

  • Full Member
  • *
  • Posts: 21
You're gonna hate this
« on: February 20, 2015, 05:14:47 PM »
75 CB550. Oil leak.

I did a complete re-seal last summer. New head gasket, base gasket, and everything in between. Put it all back together and now I'm leaking oil. I traced it the best I could. Baby powder trick and all.

Here's what I've concluded to be the culprit: 3 of the bolts that hold the cylinder down just spin and spin. They are new oem bolts, so that means the threads inside the cylinder are stripped. That means oil coming through, and that means need a new cylinder.

Me and the little lady are closing on a house next week, so new cylinder is out of the question for a while. Here's the part you'll hate...

Since I'm going to get a new head cylinder at some point, how much can I mess with this broken one? Can I pull the stripped bolts out and cover them in loctite or something? Use a millimeter thicker bolt and drive it home? Does anyone have a head cylinder sitting around they could send my way?  :)

Spring is just around the corner. I'm broke, but I want to ride.
Logged

Offline cb550fnewb

  • Enthusiast
  • **
  • Posts: 130
Re: You're gonna hate this
« Reply #1 on: February 20, 2015, 07:22:20 PM »
could try helicoils?  Probably run 30 or 40 bucks for a kit.

I have used them for stripped exhaust studs and they torqued down fine as I put red Locite on the coil and let fully dry before torquing down. (outside of the coil only, you would not want to red Locite the bolt in) 
Logged

Offline calj737

  • Really Old Timer ...
  • *******
  • Posts: 21,017
  • I refuse...
Re: You're gonna hate this
« Reply #2 on: February 20, 2015, 09:28:19 PM »
I can't understand which bolts you are referring to that are stripped and leaking... You say "cylinder bolts" but the head is held to the block via studs that pass through the cylinders. The head is held down with nuts.

If you've overtightened the nuts onto the head studs, then it's quite possible you've stripped the studs into the block. If so, you'll either have to re-tap them or install helicoils.

Perhaps a better explanation and you'll get better advice?
Logged
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Bootsey

  • Hot Shot
  • ***
  • Posts: 383
Re: You're gonna hate this
« Reply #3 on: February 20, 2015, 10:00:44 PM »
There are two bolts that hold the head onto the cylinders - one front and one rear. They could be stripped very easily I would imagine if you were a bit over zealous. If those are what you're referring to, follow the above suggestions for the fix.
Logged

Offline tlbranth

  • Master
  • *****
  • Posts: 1,659
Re: You're gonna hate this
« Reply #4 on: February 21, 2015, 09:09:09 AM »
It's been a while but my 1970 had bolts, not studs and I stripped several of them when tightening to the correct torque. I replaced them with studs I bought at Tacoma Screw. I fixed the stripping with helicoils. I think I used 2 per hole but don't remember. I'd never used helicoils before and was apprehensive but it wasn't hard and they've been working ever since. If you do have bolts, replace them with studs and helicoil the holes. Won't cost much and pretty easy to do. Good luck.
Logged
Don't own a Vanagon
Don't work at Boeing
Life is good

1970 CB750 K0
1975 GL1000
1999 GL1500
2002 VT750-CDA ACE - Momma's bike
Terry

Offline JimZ

  • Full Member
  • *
  • Posts: 21
Re: You're gonna hate this
« Reply #5 on: February 22, 2015, 06:53:52 AM »
Helicoils! That's what someone recommended I try a while back. I didn't over-torque anything. A few if the bolts just never grabbed. It's been a while, but I'm realizing cylinder bolts was the wrong description. I think it was a few of the bolts that hold the rocker cover down.

I'll try heliocoils. Thanks!
Logged

Offline calj737

  • Really Old Timer ...
  • *******
  • Posts: 21,017
  • I refuse...
Re: You're gonna hate this
« Reply #6 on: February 22, 2015, 07:04:59 AM »
If it is the small screws/bolts that hold down the rocker cover to the head, then it's likely a PO overtightened them and stripped the threads. These are 6mm holes with a 1.0 pitch and don't take more than about 6-8 ft. lbs. of torque. Essentially, hand tight.

If there was a leak, someone probably over snugged trying to stop a leak and damaged the threads. It's a seal, not a gasket under the cover, and too much compression actually is worse than not enough.

Helicoils work well. Use some AntiSieze with a proper bolt going back.
Logged
'74 550 Build http://forums.sohc4.net/index.php?topic=126401.0
'73 500 Build http://forums.sohc4.net/index.php?topic=132935.0

"Of all tyrannies, a tyranny sincerely exercised for the good of it's victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies. The robber baron's cruelty may sometimes sleep, his cupidity may at some point be satiated, but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience." - C.S. Lewis

Offline Duanob

  • Bold Timer
  • Old Timer
  • ******
  • Posts: 4,009
  • Gotcha!
Re: You're gonna hate this
« Reply #7 on: February 26, 2015, 07:51:47 AM »
Quote from: tlbranth on February 21, 2015, 09:09:09 AM
It's been a while but my 1970 had bolts, not studs and I stripped several of them when tightening to the correct torque. I replaced them with studs I bought at Tacoma Screw. I fixed the stripping with helicoils. I think I used 2 per hole but don't remember. I'd never used helicoils before and was apprehensive but it wasn't hard and they've been working ever since. If you do have bolts, replace them with studs and helicoil the holes. Won't cost much and pretty easy to do. Good luck.

Gotta LOVE Tacoma Screw eh Terry? I've had to helicoil several bolt holes on my last 550. I think the engine got over heated at one point making the aluminum soft. It worked to get the bike back on the road with no leaks.

BTW the OP never pointed out where the oil leak was coming from. The front between the head and the jugs? On the sides? Either way you will be tearing the top end apart again so save some time and space in the new house. Hope it has a nice garage!
Logged
"Just because you flush a boatload of money down the toilet, doesn't make the toilet worth more",  My Stepfather the Unknown Poet

1974 CB360T
1976 CB550K2 Resurrected
1976 CB550F2 Barn Find
1979 CX500 VG "HONDA-GUZZI"
2007 Moto Guzzi Breva 750ie
2015 BMW F700GS
Another 1976 CB550K Cafe?

  __o
_- \_<,
(*) /' (*)

Offline socal1200r

  • Enthusiast
  • **
  • Posts: 179
Re: You're gonna hate this
« Reply #8 on: February 26, 2015, 06:24:21 PM »
I vote for helicoils as well.  I had to use them to repair some stripped valve cover holes on a 1978 Guzzi V50 I had, and they worked great.  Just go slow, put some grease on the bit to grab the aluminum shavings, use red Loctite when installing the helicoil and anti-seize on the bolts, and you should be good to go.
Logged

Offline mcswny

  • Hot Shot
  • ***
  • Posts: 548
Re: You're gonna hate this
« Reply #9 on: February 26, 2015, 08:23:53 PM »
If you can go with time-Serts. A little more expensive but a lot better quality and longer lasting.
Logged
1972 CB750 K2
1997 XR600r (street legal)
1975 XL250
198 XR80

Offline atm cycles

  • Hot Shot
  • ***
  • Posts: 323
Re: You're gonna hate this
« Reply #10 on: February 27, 2015, 11:25:28 AM »
If you're talking about valve cover I had same problem. I chased threads with proper tap and used screw just a bit longer. I lucked out as it worked
Logged
Pages: [1]   Go Up
« previous next »