Leaky tach cover - help, please

[305explr]

Hi everyone,

My bike is a 64 305. I know there's no indication of an oil seal on the camshaft behind the tach cover, but...is there one?

I've had a pesky leak from beneath the cover for some time. I HAD a seal there (??) and upon removing it (bc it's not pictured or listed, and my local vintage Japanese tech said to remove it), the bike leaked profusely and immediately upon start up. Very much unacceptable. Yes, I have a factory gasket and I'd coated it lightly w sealant in attempt to halt what was originally just a drip. Upon removing the seal, the leak got worse.

Everything is apart and cleaned. I'm open to advice before reassembly.

Thanks

[DJM]

Are we talking here about a GASKET between the tachometer drive casting and the cylinder head or an OIL SEAL on the tachometer drive cable.

I can't believe any competent mechanic would suggest leaving either of them off as they were / are both there for a purpose, so YES your bike should have both.

Make sure that your fixing screws aren't too long otherwise the screws will bottom in the holes in the cylinder head and not pull the parts together enough to give a good seal, or any seal at all.

The oil seal on the tach cable is easy to loose and replacements are not shown in the parts book but I have a part number somewhere for the seal if you find yours is missing.

Shouldn't be too difficult to get a good seal if you use all the correct bits and a bit of care.

[cknight]

Also, check to make sure that the left outboard cam bearing is not sticking out too far from the machined surface that the tach drive tightens against. You should be able to hold the tach drive casting against the head without the gasket in place, and have less clearance than the thickness of the gasket. If the tach cable does not have a seal (part number 91256-VD6-003, Honda Power Equipment), make sure that the one you install has the flat surface pointing away from the engine. Regards, Chase

[305explr]

These are helpful replies, thank you each. They have introduced another problem: I did NOT have the seal that sits at the end of the tach cable. I did look inside my original cable that I'd kept in my spare parts bin and I saw what you each were referring to.
My aftermarket tech cable does not have a cup in which the seal can sit, however; that surface is flat. And, it's a different o.d.
I may revert to my old, original cable.
HOWEVER, the seal I'd begun this post in regards to is a different one. (!) I'm talking about a seal that sits against the camshaft bearings.

DJM:

[305explr]

I'm sorry. My phone did not allow me to continue that post.
Please see the attached pic of the seal I was told to remove. Should there be a seal in this location?

[DJM]

There is no oil seal against the camshaft bearing, just the gasket, no room for a seal anyway it isn't required.

[305explr]

Okay then. Thanks for clarifying.
Hmm...I am not sure what the problem is at this point.

-I dble checked the depth of the camshaft bearings and there's ample room for the cover flange.
-The cover sits snugly against its mating surface.
-I'll double check the depth the bolts will need, but everything's stock.

Maybe a crankcase breathing problem?