[LotusSevenMan]

We have all heard the old jokes about Royal Oilfields blah blah.
Well mine has started this weep from the primary case.

Traces of oil underneath prmary case so:-

1) I took the cover off and moved the 'O' ring seal around the locating slot. Back together. Leak.
2) New 'O' ring seal bought and fitted. Leak
3) The new 'O' ring fitted with Hylomar non setting sealant/gasket. Leak
4) Cover tried with fairly loose hold down nut right through to fairly tight. Leak
5) Suspect cover is warped. Had it checked for straightness on a surface table. Perfect!
Geez, what can I do to sort this weep?
I am considering a paper gasket but ?

HELP 

On another note I have stopped a leak that was coming from the gearbox via the shift/kickstart shafts with the use of external 'O' rings squeezed up against the casing by the shift lever etc. Mine is a right side shift and the slight leak meant oily marks on the exhaust can. Looked horrible. Not now 

[PhilJ]

There's got to be a better answer but on an old Triumph 1964, me thinks, I took everything apart and use 3M  monkey snot, I don't know it was yellow, that worked. But where you need to take the cover off periodically, it could be done but would be a hassle. But in '64 every thing about Brit bikes was a hassle. 

[ace.cafe]

First thing is to make some attempt to identify if there is some particular spot where it is leaking. It could be everywhere, but it is most likely to be at a certain place.
That is where you can start.
It's hard for any of us here, who can't see what's going on, to be of much help.
But, if you can locate the main spot of the leak, then it may become clearer as to what needs to be done to fix it.

Even if the cover is perfectly flat, it is possible that the bolt that holds the cover on is slightly canted, thus causing uneven pressure to be applied all the way around. Or it is possible that the machined surface under the nut on the fixing bolt might be machined not parallel to the cover mating surfaces, thus causing uneven pressure around the mating surfaces.
These are possibilities, and the issue could possibly lie somewhere beyond the simple mating surface expectations.

[cyrusb]

Don't take it so hard, It's a Royal Enfield remember? A little weep? Mine has the same story, thats what rags are for. I'm just so damn happy my crank hasn't broken in two.

[LotusSevenMan]

Ummm. A little weep. True, but it annoys me so WILL get sorted somehow.
Might be the size of that 'O' ring seal as it appears to be the same size as the original but?
Ace.Cafe.
Of course the oil gathers at the lowest point of the case then drips onto the concrete area I keep the bike in. Grrrrrr. Yes, I could/will  use a drip tray but that's not the answer.
The 'O' ring seal is rather 'soft' so the same size but a harder grade might help as I'm sure it just compresses completely in the scallop in the main case.
Cyrusb
LOL. Defeat is not an option!!!! 

[Spitting Bull]

I would find this really annoying, too.  Do you find the oil after a run, or after the bike's been parked?  Do you park on the sidestand or the centre stand?  Reason I ask is that when using the sidestand, people have found oil on the bottom of the primary chaincase but it was actually coming from somewhere else.  The lean of the bike when parked meant that the primary case just happened to be where the oil ran to before finally dripping off.  Just a thought, as the work you have done on the primary case should have stopped any small leak there.

Tom

[ace.cafe]

Well, I sort of gathered that it was collecting on the bottom and dripping off.

What I really meant was, where is it actually getting past the seal?
Very rarely does oil pass a seal all along its length. It almost always finds a certain  spot where it goes out, and then collects on the bottom and drips off.

If you park the bike, wipe it off clean, and watch for the oil to start appearing somewhere along the edge(if that's where it's coming from), then you'll know.
Yes, it takes some time, but could yield success.

I was a professional British car mechanic for about 15 years "back in"the day", so I have learned a thing or two about oil leaks in my time
Patience and detective work pays off..

[LotusSevenMan]

Saw my local dealer today. He suggested a couple of things.
Firstly, had the inner case come slightly loose and  is it allowing oil to run down that way and secondly could the 'O' ring groove be machined to deep?

When I said that even on very low poundage on the hold-down nut the casings seemed to be flat against each other (metal to metal) he said that didn't seem to happen on others he has. A quick look confirmed that the inner and outer primary cases on other bikes appaer to have a tiny but viewable 'gap' between them.
Doesn't happen with mine.

Ace.Cafe.
I can see your reasoning but I am too active to watch paint dry. It seems to take an age to leak as in overnight, but leak it does.
Might try the fluid loss test with auto transmission flud in the case as thinner so might seek out the 'leak' easier/quicker!!!!!!

[Jon]

It's called character,steal the cat's litter box and shove it under the bike. This
will of course piss off the cat and possibly the wife if you use the cat to wipe up
the oil. It'll stop the cat from rusting though.

On a less whimsical note could the leak be coming from the gearbox or
clutch oil seal and running down the back of the inner case?

[petefletcher]

Just something to check.
I thought I had a leak from the bottom of the chaincase but finally found it was coming from the alternator wire sealing grommet. A new grommet sorted it but was a pain to fit. I had to cut the connectors off the wire and remake the connections. Dry as a bone now.

[LotusSevenMan]

Jon

It'll stop the cat from rusting though. LOVL 

Well I might have found an answer (though if it is THE answer only time will tell). With cover removed I considered what Ace.C said. Could it be running down the outside of the INNER casing via the lower fixing c/sunk screw? Worth a look. Removed alternator. You can see the three c/s screws and get to them OK with an extended allen key. "Bet they're tight" says I.
Err, no. I got about an eighth to a quarter turn on them (difficult to say with accuracy). Loosening off or gasket compression? Who knows/cares?
Certainly not tight tight if you get my drift. Put it all back together (cut-out rectangles of plastic milk containers make great non-metallic shims for refitting the alternator).
Filled it all back up with the requisite amount of oil. Ran it for about ten minutes. OK. Keep checking it now about every half hour. OK so far for two hours. Fingers crossed.

PeteFletcher.
My alternator wire sealing grommet is pretty poor, but no worse than it has been all along.
The leak showed without it running you see so must be lower than that. Good one to watch though. Thanks!

[LotusSevenMan]

Still dry 3 hours + later!

Whey hey!!!!!! 

[LotusSevenMan]

Update.
Rode out yesterday and with a couple of stops for a cooked English breakfast and and icecream (decadence eh?) I covered 128 miles.
Bike primary case side dry as the proverbial bone.
Very satisfying to have sorted it. 

[PhilJ]

Good on you LSM, perseverance pays dividends. Now we have something else to ponder.

[ace.cafe]

Glad to hear you fixed it.
Good work.