Help with an oil leak - Rebuilt CB77

[Spargett]

Got an oil leak that I can't seem to solve for the life of me. Looking to the forum's wisdom to lend its creative thinking or experience.

Spend a year restoring and rebuilding (engine) the CB77. Had 2nd gear go on me, split the cases and ended up replacing the transmission with a low mileage from a CL.

Upon reassembly had an oil leak that would come from the right side, and paint the tire with oil from the chain. First thought is oil seals. Replaced the clutch rod seal. Still persisted. Ended up splitting the cases again and redoing everything with new gaskets to oil seals. Leak still persists upon reassembly all the same. Replaced clutch rod with an NOS thinking it could be worn. Leak still persists.

All the evidence points to the clutch rod seal, which leaks onto the sprocket/chain and makes quite a mess. Been trouble shooting it for over a year. I'm really at a loss. Any ideas or help is great appreciated. Look forward to hearing from you guys.

So the questions:

• 1. Could it be really bad luck with the seals?
  2. Could there be added stress from the clutch somehow which opens in the inner portion of the seal enough to let oil out?
  3. Could there be too much oil pressure and that's the weakest link?
  4. ???

You'll see there's a bit of sealant around a couple of the seals. I first installed everything without per recommendation, then tried with sealant as well.

[kirbb9]

sparget, We have used arid extra dry deodorant to check for leaks. It sprays on in a dry white powder and shows immediately where the leak is coming from. Also could have a crank oil seal leaking and getting to the sprocket?

Brady

[LOUD MOUSE]

Good question and great pics.
I can't see where the TOP VENT HOSE is located so I would ask"is it installed at the case hole"?
If it is and you have had the top engine cover and gaskets off tis possible the gaskets are installed incorrectly.
That said.
If the gaskets are installed with the oval holes to the rear of the engine you will "PUDDLE" oil in the top and the vent hose will blow the oil through the tube and "ALL OVER YOUR ENGINE".
Any questions on this you can CALL ME AT 830-895-0654. .......lm

Got an oil leak that I can't seem to solve for the life of me. Looking to the forum's wisdom to lend its creative thinking or experience.

Spend a year restoring and rebuilding (engine) the CB77. Had 2nd gear go on me, split the cases and ended up replacing the transmission with a low mileage from a CL.

Upon reassembly had an oil leak that would come from the right side, and paint the tire with oil from the chain. First thought is oil seals. Replaced the clutch rod seal. Still persisted. Ended up splitting the cases again and redoing everything with new gaskets to oil seals. Leak still persists upon reassembly all the same. Replaced clutch rod with an NOS thinking it could be worn. Leak still persists.

All the evidence points to the clutch rod seal, which leaks onto the sprocket/chain and makes quite a mess. Been trouble shooting it for over a year. I'm really at a loss. Any ideas or help is great appreciated. Look forward to hearing from you guys.

So the questions:

• 1. Could it be really bad luck with the seals?
  2. Could there be added stress from the clutch somehow which opens in the inner portion of the seal enough to let oil out?
  3. Could there be too much oil pressure and that's the weakest link?
  4. ???

You'll see there's a bit of sealant around a couple of the seals. I first installed everything without per recommendation, then tried with sealant as well.

[Spargett]

Thanks for the reply LM. Didn't catch the email notifying me.

The top vent does not have a hose on it, and I have not found any oil coming from this area. I will give you a ring to discuss in person. And make sure to share any valuable info with the forum. Talk soon, and good to hear from you!

- Scott

[SMBH]

Hi Spargett, hope you sorted your problem im no expert so I canot help you. I am new to this forum as I have just purchased a CB77, my reason for posting is can you please tell me the following -

SIZE OF FRONT TYRE AND MAKE

SIZE OF REAR TYRE AND MAKE

SIZE OF FRONT WHEEL RIM IS IT 1.60 WM1 STANDARD

SIZE OF REAR WHEEL RIM IS IT 1.85 WM2 STANDARD

How do's the bike handle with the change of tyres at the moment the bike I have has standard 1.75 front and 3.00 rear. I wish to change the tyres on my bike and was wondering about the clearance by putting larger tyres on.

I have don a search on the forum but and red all there is but your bike looks just great.

Thank you for your time.

[e3steve]

@Scott: Your bike looks lovely in that garage picture! The throttle cable arrangement doesn't look right though; seems a bit uncomfortable. It should exit the grip pointing forwards and then pass above the headlamp 'ear', between it and the headlamp bucket.

Have you tried running the bike with the r/h engine cover off? That's what I did in order to locate my leak. I was then able to observe the oil 'bubbling', when hot, from the crankcase facings. Run the bike up to temp first, on a short ride, then whip off the muffler and the casing, pop the muffler back on and run the motor, whilst on the centre stand, and work up through the gears until you attain aground 3Krpm in top. I'd suspect the output shaft seal, in your case, but that remains to be seen(?).

I arranged mine on its stand so that I was able to turn the bike a bit and have the front tyre in contact with a brick wall (just in case.....).

@SMBH: where in "England"; I'm in Southern Hampshire. I have many spare parts, should you find the need.....

[SMBH]

Hi e3steve I live in Redditch 16 miles south of Birmingham.

See my posting in the "Help wanted on how to ship to the UK" thread this will explain the bike I have just purchased on page 2.

Not yet in my hands waiting for cheque to clear thanks for the offer of help with any parts I hope not to want many the bike has cost me a lot of money.

Cheers Mike.