Author Topic: oil leak?  (Read 1588 times)

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Offline HonderCB

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oil leak?
« on: July 10, 2012, 04:41:50 PM »
my 77 F2 is developing quite the oil leak.  I always just assumed it was the gasket between the jug and head, but it is now getting worse and is all over the fins both above and below that gasket.  When i ride i end up with oil spray on my shins.  It is happening on both sides, but much more prominent on the "passenger" side.  Any body know what causes this?  Need an idea before i start dissecting.

Dunno if you can tell much from the pic, but it is all over the fins above and below the gasket
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline MCRider

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Re: oil leak?
« Reply #1 on: July 10, 2012, 05:07:18 PM »
If its in the fins above the head gasket, its the 6 pucks underneath the cam bearings. If the engine has been worked on and the four cam bearing hold down studs were removed and reinstalled, they can wick oil to the outside as well and deposit it about halfway down the head fins, same as the pucks, where it moves to the front at rest or the sides while in motion.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline HonderCB

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Re: oil leak?
« Reply #2 on: July 10, 2012, 05:16:46 PM »
thanks for the quick reply ron, how hard are those pucks to change?
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline MCRider

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Re: oil leak?
« Reply #3 on: July 10, 2012, 05:41:07 PM »
thanks for the quick reply ron, how hard are those pucks to change?
Not too hard as these things go. If you don't have a frame rail kit, you'll need to pull the engine. Then rockerbox, rocker arms, and cam shaft. Then the cam bearings. That's as far as you have to go. The head stays oon, you don't disturb the head gasket.

The pucks are on the bottom side of the bearings, aka cam towers, aka cam blocks (there are 2, each with 3 pucks). Put fresh soft pucks in with a little sealer, reassemble and go.  They are rubber discs about the size of a quarter+.

Shop time would be about 3-4 hours, if you had the parts, knew what you were doing. Out, fix, and back in.

Figure a weekend, 2 six hour days otherwise.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline HonderCB

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Re: oil leak?
« Reply #4 on: July 10, 2012, 05:48:19 PM »
no frame rail kit... might be a good excuse to put one in ;)  know of a good source?

Thanks for all the info, its greatly appreciated
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline goldarrow

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Re: oil leak?
« Reply #5 on: July 10, 2012, 06:04:52 PM »
i think you're referring to cb750 frame kit?  check out this thread http://forums.sohc4.net/index.php?topic=101832.0
Life Is Full Of Challenges - And My Backyard Is Full Of SOHC4's

CB550 K0
CB750 K0, K2, K23 JDM, K45, K5
And the little ones z50r, xr50r, st90


750k5 http://forums.sohc4.net/index.php?topic=114817.0

Offline HonderCB

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Re: oil leak?
« Reply #6 on: July 11, 2012, 02:48:11 PM »
If its in the fins above the head gasket, its the 6 pucks underneath the cam bearings. If the engine has been worked on and the four cam bearing hold down studs were removed and reinstalled, they can wick oil to the outside as well and deposit it about halfway down the head fins, same as the pucks, where it moves to the front at rest or the sides while in motion.

Ron, do you (or anyone else for that matter) have a part number for these rubber pucks?  I cant find them in the parts diagram
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline jtb

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Re: oil leak?
« Reply #7 on: July 11, 2012, 03:07:39 PM »
Pretty sure it is #18 on the cylinder head diagram at service honda. 

6 required
RUBBER, SEALING
91318-300-013
http://www.servicehondapsn.com/fiche_section_detail.asp
1977 CB750F
1985 V65 Sabre
1986 VFR 750 (gone but missed greatly)

Offline MCRider

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Re: oil leak?
« Reply #8 on: July 11, 2012, 05:10:26 PM »
Pretty sure it is #18 on the cylinder head diagram at service honda. 

6 required
RUBBER, SEALING
91318-300-013
http://www.servicehondapsn.com/fiche_section_detail.asp
That be they.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline HonderCB

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Re: oil leak?
« Reply #9 on: July 12, 2012, 05:44:15 PM »
Sweet, thanks for the help guys, i got the seals ordered.  Hopefully i can get the engine pulled and fixed soon.
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline HonderCB

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Re: oil leak?
« Reply #10 on: July 18, 2012, 11:38:34 AM »
Just got off the phone with Carpy, and i ordered his frame kit.  I wont be doing any serious aggressive riding, and from what i have read his kits are pretty stout, so i dont think there should be any problem having it on my bike.  I like it cause it looks like i wont have to do any torching or welding to install, so i can do it with the engine still in the bike... i really didnt want to pull it for this.  Plus it will be easier to pull the engine some day when i need to  I might even make some brackets to tie into the upper frame rail also to make it stronger.  Now when everything gets here i can start on my first ever mechanincal SOHC project and hopefully get this oil leak sorted out.  Everything i have done to either of my bikes to this point has been cosmetic, and i have never had an engine apart bigger than a single cylinder atv top end.  Wish me luck!
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD

Offline MCRider

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Re: oil leak?
« Reply #11 on: July 18, 2012, 11:45:49 AM »
Just got off the phone with Carpy, and i ordered his frame kit.  I wont be doing any serious aggressive riding, and from what i have read his kits are pretty stout, so i dont think there should be any problem having it on my bike.  I like it cause it looks like i wont have to do any torching or welding to install, so i can do it with the engine still in the bike... i really didnt want to pull it for this.  Plus it will be easier to pull the engine some day when i need to  I might even make some brackets to tie into the upper frame rail also to make it stronger.  Now when everything gets here i can start on my first ever mechanincal SOHC project and hopefully get this oil leak sorted out.  Everything i have done to either of my bikes to this point has been cosmetic, and i have never had an engine apart bigger than a single cylinder atv top end.  Wish me luck!
I have an APE frame rail kit, from the 80's. No longer available. Carpy's is a knockoff, though actually a little better. Never had a problem with mine, many many miles. I had some brackets made to tie up to the backbone just as you mention. Don't know if its any better, but it feels good.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline HonderCB

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Re: oil leak?
« Reply #12 on: July 18, 2012, 11:55:47 AM »
thanks for the reassuring words ron, i think i will be happy with it.
-Scott, just a F'er from Illinois-

77' CB750F
81' CB650C - SOLD