CB77 - Oil leaking woes

[ryan305]

Hey guys,

So this past year I did a bit of a mechanical restoration on my 66 cb77. Ive had my fare share of struggles with the bike but manage through. Two issues were difficult to find for me, blocked gas cap vent and points cover arcing. Those ignition and fuel issues are gone now and it's time to finally enjoy it.

After my first long ride in a while, I noticed the crank seal is leaking (again) and the tachometer cable is leaking too. I have replaced both multiple times.

The RH crank seal I have not been confident with my installating as it always feels like it drags going in. This is using NOS Honda crank seal. (I'm talking about the large seal not the small one on the starter sprocket). When I inspect the seal, it is always leaking on the outside edge. The cases are clean with no scoring.

The tachometer cable I have replaced the original with one from classichondarestoration and from Thailand eBay Honda replica. Both cables leak at the tachometer creating the leak onto the fender.

For the crank seal, does anyone have any recommendations, tips or tools they use to install these properly? Should I try freezing the seal?

For the tach cable, are the replica cables just poorly made? Or could there be something in the tach drive housing that I missed or misinstalled? How do I resolve this?

Thanks for your time and any knowledge you might be able to share.

Ryan

[LOUD MOUSE]

The case edge is sharp and I recommend you use a sharp object (knife/edge scraper) to angle it.
Then you can tap in a circle to install the seal. ..........lm

Hey guys,

So this past year I did a bit of a mechanical restoration on my 66 cb77. Ive had my fare share of struggles with the bike but manage through. Two issues were difficult to find for me, blocked gas cap vent and points cover arcing. Those ignition and fuel issues are gone now and it's time to finally enjoy it.

After my first long ride in a while, I noticed the crank seal is leaking (again) and the tachometer cable is leaking too. I have replaced both multiple times.

The RH crank seal I have not been confident with my installating as it always feels like it drags going in. This is using NOS Honda crank seal. (I'm talking about the large seal not the small one on the starter sprocket). When I inspect the seal, it is always leaking on the outside edge. The cases are clean with no scoring.

The tachometer cable I have replaced the original with one from classichondarestoration and from Thailand eBay Honda replica. Both cables leak at the tachometer creating the leak onto the fender.

For the crank seal, does anyone have any recommendations, tips or tools they use to install these properly? Should I try freezing the seal?

For the tach cable, are the replica cables just poorly made? Or could there be something in the tach drive housing that I missed or misinstalled? How do I resolve this?

Thanks for your time and any knowledge you might be able to share.

Ryan

[cknight]

Some of the IMPEX brand replacement cables have the seal installed backwards. Make sure it's facing properly (flat side toward the tachometer), as no oil should be going up the cable. Regards, Chase

[border0_3]

Ref the tacho cable, we had a new one with no seal which caused a bit of grief.

The seal or o-ring should be the last item on the cable and fit tight against the tacho drive end.

Maybe the seal it too thin or the cable nut not done up tight enough?

All the best.

[cknight]

The seal is Honda part number 91256-VD6-003, measuring 5x14x3mm. Thanks, Chase

[ryan305]

Thanks everyone, going to order a new crank seal and the tach cable seal and give it another go.

Ryan

[Nick]

When installing the crank seal, use gasket sealer on the outer seating surface of the seal. This makes the seal easier to install, will help prevent damage during installation and will also help prevent leaks.

As with any engine, excessive oil leaks can also be caused by combustion pressure leaking past the rings and pressurizing the crankcase.