Multiple oil puddles on ground after short ride

PDE 70 Commando · 2026-04-04T07:59:23-0600

MichaelB said:
Where does the reed valve vent to?

I added a port to the oil tank on the top right side, well above the level of the oil.

PDE 70 Commando · 2026-04-04T08:07:04-0600

B+Bogus said:
I'm guessing yours is the 'Hamcan' oil tank which forms the rear face of the air filter box?
The tank vent is an internal pipe which exits into the airbox, so it's just a hole in the front face of the oil tank. Have you checked if this is venting oil?
If this internal pipe has fractured it would dump oil into the airbox, and then everywhere else.
Later side-mounted tanks have an external pipe which plugs into the back of the airbox, so it's easy to check.
My '70 had a frustrating oil leak which turned out to be the triangular plate at the back of the timing case - a sliver of the thread broke away and wedged itself between the case and the plate; it took some finding
Happy to report it's now oiltight, so they're not leaky by design - as @ludwig says.
Incidentally, I removed the timed breather disc and plugged the pipe into a cheap PCV close to the tank, which worked well enough for a stock motor.

Yes, this is the tank I have. I wondered about a leak in that pipe and the effect it would have. I think that a leak in this pipe would have dripped out of the airbox vent hole during my overnight static leak test -- unless the fracture was ABOVE the level of the fluid that I used. Hmm...

Man, I don't want to pull that tank again! But I sure will if I have to.

Also, shouldn't I expect to have a very oily air filter element if this is the case? I guess "very oily" is a subjective assessment; there is some oil on the element. It's not dripping yet, but perhaps I haven't ridden it far enough.

kommando · 2026-04-04T09:34:54-0600

The engine breathes oil, not all gets removed at the oil tank so the oil tank breathes less but still some oil. Not enough to cause any dripping but the filter will shows signs of oil.

jseng1 · 2026-04-04T09:39:17-0600

Immerse the oil tank in water and use compressed air (low psi) to find the leak. For an oil tight Norton you need yamabond 4 or motoseal 1 for the cases, Pliobond on the HG, fiberglass reinforced silicone gaskets everywhere and oversized O rings. My Norton hasn't leaked a drop in years.

Multiple oil puddles on ground after short ride

PDE 70 Commando · 2026-04-04T19:16:20-0600

phippsy said:
When I fitted my reed valve to my sump I had oil every where all over back tyre drips everywhere. Long story short , I put an o ring on my oil tank filler cap as well as cork washer , I have to do it up with a wrench but no more oil . Worth trying sorted mine right out .

The top of my tank seems to stay dry. Not sure how!

robs ss · 2026-04-05T00:14:11-0600

phippsy said:
When I fitted my reed valve to my sump I had oil every where all over back tyre drips everywhere. Long story short , I put an o ring on my oil tank filler cap as well as cork washer , I have to do it up with a wrench but no more oil . Worth trying sorted mine right out .

That surely must be a sign of significant blow-by whilst running.
After the first few seconds of oil/air returning to the tank there should be almost nothing - other than blow-by gases (or an air leak into the engine, like an old breather connection not properly plugged)

Also - blowing into a sealed, pressurised oil tank will reduce the effectiveness of your reed valve.

Tornado · 2026-04-05T00:44:29-0600

I once had an oil line from pump to oil filter/return to tank develop a crack amd spew oil in the areas you describe. It was the flexible metal conduit on the hose that cut the rubber hose near the end...but of course you need to check all your lines throughly, esp if originals.

YING · 2026-04-05T04:13:50-0600

B+Bogus said:
I've never seen brake cleaner remove paint otherwise it wouldn't be fit for purpose. Maybe different formula in the US?
I've been using it for years with zero issues. Kerosene would be an option i guess, as this is what I have in my parts washer.

Bogus,
Like you, I have never had any problems using brake-clean. I use it all the time for various uses and wish it was available years ago!
Mike

Multiple oil puddles on ground after short ride

PDE 70 Commando

PDE 70 Commando

kommando

jseng1

PDE 70 Commando

robs ss

Tornado

YING

Pittsboro,NC

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