1981 CB750K oil pipe banjo fitting leak

[TBItruck89]

Howdy, I've been working on tuning up this bike I bought recently and have run into a snag.

The previous owner told me that there was a small oil leak that he couldn't track down, and I determined that it was coming from the top banjo fitting of the hard oil pipe that runs from the crankcase up to the cams. I took it off to clean it and noticed that the aluminum sealing washers were deformed like the banjo bolts had been overtorqued at one point. So I bought new copper sealing washers, put it back together, and the damn thing leaks worse than before. I can't even let it idle without making a mess

I can't find the actual banjo bolts themselves for sale anywhere, so replacing them might not be an option. Any ideas on how to fix this leak? I couldn't find anything about this problem on the CB750 searching online, but it seems like on other bikes people replace that pipe with braided line, which I wouldn't mind doing if I knew where to find the line and nipples etc.

[TOOLS1]

The banjo bolts might be available at an autoparts store. You would need to take yours in, and match them up. I wonder if the line/fitting might be cracked. With the oil pressure on that fitting, it would not take much for it to really leak. as for a braided stainless line, google, and see if you have a "Tompkins Ind" near you. I have them make up lines for me.
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[sgtslag]

I believe the parts you want are on BikeBandit.com's web site here:  #23, Washers; #11, Oil Bolt; #10, Oil Control Bolt; and #9, Oil Pipe.  The washers are available to ship, while the rest say they are not.  You may have to go to a shop to have them order directly from Honda, if they are still available at all.  If all you need are the washers, you won't have any difficulties, other than S/H costing more than the parts...

The max. oil pressure, at 7,000 RPM is 72 PSI, as per the FSM.  It will make a mess very quickly...  Had leaks on my oil cooler, on my '79 when I first installed it using worm clamps on the hoses, instead of the T-bolt clamps it needed.  Found out just how fast it could spew oil!  Came out like a jet-stream, took 5 seconds to make a puddle a foot across, beneath the transmission!

Best of luck.  Cheers!

PS:

Not terribly familiar with braided hoses, but you might get by using T-bolt Clamps on them, over the bolts.  I used T-bolt Clamps over rubber hoses, and they held perfectly, no issues.  I believe the inside of those steel braided hoses are rubber.  Maybe someone with more experience/knowledge can chime in and correct me, if I'm wrong?  Double Cheers!

[TBItruck89]

Thanks for the thoughts. I hadn't considered the fitting itself being cracked. Unfortunately, no Tompkins near me. I'll check around local shops and see if anyone makes braided lines.

I really like the idea of using rubber hose and t-bolt clamps at least just to get me running for the riding season. Looks like McMaster Carr has stainless clamps small enough for it, just need to find hose rated to high enough temp & pressure.

[TOOLS1]

TBItruck89 wrote

Thanks for the thoughts. I hadn't considered the fitting itself being cracked. Unfortunately, no Tompkins near me. I'll check around local shops and see if anyone makes braided lines.

I really like the idea of using rubber hose and t-bolt clamps at least just to get me running for the riding season. Looks like McMaster Carr has stainless clamps small enough for it, just need to find hose rated to high enough temp & pressure.

I would NOT DO IT! I lost an engine last year because of rubber hose. It's a cheap way to spend a lot of money.
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[TBItruck89]

Just to update, I found a local hydraulic parts shop that can make hoses with banjo fittings, which makes me feel better since the banjo bolts have pretty small orifices which I assume restrict the flow. They couldn't do nipples because of the coarse pitch of the threads (M10x1.25 instead of the hydraulic thread standard of x1.0).