clutch cover leak 66 CA-77

[dreambike]

I have a 1966 CA-77 where the crankcase cover with new gaskets, leaks. I have tried 3 !!! gaskets, the first two attempts I used Permatex gray. I took the cover and carefully rotated it on a 1/4 thick glass shelf, marked it with an marker pen, and sanded until it was smooth.
The two guide pins are the same length, and were lightly sanded as well in case too much was taken off the cover.
I confidently thought now the cover's surface is flat (true) and the opposing side doesn't look like there is divets or deep scratches etc.
So I placed the new NOS gasket w/o sealer back on, filled with oil, and a few days later found it to drip at the buttom, in two places! what the hell can be doing this?
I did notice, on the clutch cover one of the two guide pin holes was deeper then the other, which I thought strange.Why ?
Does any body have comments or suggestions on why this cover is leaking, and why one guide hole is deeper then the other hole. Thanks for any comments

[DJM]

First, make sure that the leak is from the gasket and not the gearchange shaft oil seal.

When I rebuild my engines I have a set of socket screws (allen bolts) which I use for initial assembly.

Fit your side cover case and then using socket bolts instead of normal crossheads tighten the screws REALLY tight with an allen key. Leave the engine overnight for the gasket to 'settle' and then tighten them again.

Then take out the socket bolts, one at a time, and replace them with the correct crossheads, if you have one, use a decent tee bar screwdriver to tighten them.

When these engines were built at the factory the screws were put in VERY, VERY tightly and you will be lucky to get the side cover oil tight if you're just using a normal screwdriver.

My method takes a bit of extra time but the cases don't leak!

Just as an aside, the threaded holes in the crankcases are quite deep and it is usually possible to fit a screw one size longer than that specified in the Parts Book. This helps to get the screws really tight and gives the fifty year old threads a slightly easier time.

If you try this method and it works for you, please let us know the outcome.

[the-chauffeur]

If you're sure it's the cover that's leaking, you may be able to identify where the problem is by using very thin feeler gauges to trace around the join to see if there are any gaps. As you've identified, generally leaks occur where there are knock/locating pins that are poorly fitted which force the side cover out too far, or where the mating surfaces aren't flat to each other.

Personally, I avoid going too heavy on the cover screws - I've seen too many stripped mount holes. But that's just me. That said, if you're going back to screw head fasteners, turn them in and the tap them with a manual impact driver that's been set to tighten.

[DJM]

I've also heard of people using two gaskets with a sealant between them but if everything else is good it shouldn't be necessary.

Just something else to try though if all else fails.

I know how frustrating this is as Hondas just aren't supposed to leak oil!

Good Luck.