Crank breather pipe routed to base of oil pan

Hey All,

Got a little mystery part that I was hoping someone knows something about.

Been rebuilding a 75 Z1 engine that was once in a drag bike and have come across something I've not seen before - a pipe routed from the bottom of the breather into the oil pan inside the engine.

Anyone seen one of these before?

Wondering if this was supposed to be part of an oil cooler?

Thanks in advance.

(pic taken from the bottom of the engine).

Thats a new one on me
Does it go deep enough to be submerged in the oil sump ?
Dave

Oh yeah. Looks to go down to within a 5-7mm of the bottom of the pan.

A pic would help.
Steve

This pic should give a pretty good sense of how deep it goes. Again, the engine is upside down on a stand and the other end slots into the rear breather hole.

I might be completely off the mark here but instead of being a breather maybe it's an oil return from the breather? Like the breather vents to a large can where the oil seperates from the vapers and returns to the crankcse.
Just a thought...

azman857 wrote: I might be completely off the mark here but instead of being a breather maybe it's an oil return from the breather? Like the breather vents to a large can where the oil seperates from the vapers and returns to the crankcse.
Just a thought...

That may be. My thinking at this stage was that it was unlikely to be part of a "conventional" breather system as surely as the oil heated and was sloshed around it would make its way up the pipe.

Have been wondering if it was meant to be some kind of return for an oil cooling system.

As mentioned this came off a bike that was formally a drag machine but was really just a roller when I got it and was mostly apart, with the whole top end off. It hasn't been run since probably the early 90s. The bike had a clubfoot swingarm, super long rearset pegs, and some frame-bracing. The engine had a number of drag related mods too, like the starter motor and mechanism had been pulled, head has some porting, what looks to be an aftermarket shift drum, welded crank, etc.

I've stripped everything down, added more bracing to the frame, swapped the swinger for a Zepher 1100 unit with Works shocks, zx7 front end and mags and now I'm re-assembling.

Engine-wise, I'm going with 1075 with Wisco pistons on this guy and some slightly more aggressive cams, a set of 29mm smoothbores and I have a Yoshi 4-1 pipe from the 70s that may or may not be genuine, as I can find no marking on it at all, though if it is a copy, it's a very good one..

Here's a pic of the chassis as it stands now. (please excuse the pic - need to take some better ones).

Unless it is a very bad design it cannot be a breather .
For that to work the end must be clear of the oil and then why not just have a pipe ending at the top of the oil filler cap as usual .
It's unlikely to be an oil return for obvious reasons.
So with it being in the oil it really has to be an oil pick up.
If the engine previously had a Rajay turbo fitted it may be the feed for a separate oil pump.
Rajays really need more oil pressure than the lowly 3psi or less that the zed pump kicks out or the centre plain bearing will run dry.
A pic of the other ( oil filler ) end would be good.

Below is a pic of the other end.

As you can see, it ends flush with the top of the case.

Also - the inside of the pipe is not threaded.

As others mentioned, it's probably an oil pickup. If it was anything to do with the breather, any positive crankcase pressure would push oil up the tube. A breather or oil return should end above the oil level in the crankcase.

It's a nice neat job but I can't see any point or use for it as it stands and in 35 years of racing i've never seen that done before and that is saying something.
It's no good as a breather and it would impede oil draining back into the sump via that tube.
Unless there is an 'O' ringed push fit extension as part of the breather cover enabling the attachment of an oil hose externally it is just extra weight.
Maybe there's something missing that got mislaid or not passed on when its racing life ended.

Thanks to everyone who helped out here.

As it seems that if it was part of a system (likely an oil cooling system), that is incomplete the mystery may never be fully resolved and I'll be pulling it as Zed1015 said, it's just extra weight.

Should really do a build thread on this beastie...