Oil travel (or not) along rocker pipe

[Phil C]

Evening all,  Bit disappointing.  I made a new rocker oil feed pipe (no hose segments at this stage, just metal.)  Before fitting I blew through the end and the route along the pipe to both banjos seemed to be clear. I fitted it, turned on the oil, and, with the top off the oil tank, started kicking the engine over whilst watching for the oil returning to the tank, which it duly did. I expected that soon afterwards it would also appear at the banjos, which I had left loose.  But about a hundred kicks later, no sign of oil at the banjos. Any ideas why please?   Phil

[DAVE BRADY]

Hi Phil,

Did you try blocking the return to the tank with your finger?  This will cause the returning oil to push up the rocker feed pipe.

Dave.

[Phil C]

No I didn't, Dave.  I guess maybe I should have.  But then I wouldn't be doing that if the engine were running.

By the way, here is a pic of the pipe. I wouldn't have thought any of the bends too tight?

Phil

[Phil C]

Oh, by the way, actually when I said "I made a new rocker oil feed pipe" I was taking credit where it wasn't due. I actually bought a pipe (with the t-piece at right angles) and bent it to fit.   Phil

[DAVE BRADY]

No not while riding but it would show that the oil is getting there.  Not a huge amount goes up there any way but once you have it up there by blocking the oil tank return tighten the banjos and kick a few more times.  Start the engine and slacken one banjo to see if the oil is getting up to the rocker box.  As it is on the return there is no pressure so a trickle rather than a squirt.

Dave.

[Phil C]

But obviously I wouldn't want to have to put my finger over the hole every time I start the bike? I don't understand why it's not getting there without that.   Phil

[DAVE BRADY]

No, but once you know it is getting there you will know it is OK. 

Dave.

[Beesy]

The oil pump will be spinning several thousand times faster when the engine is running too. That will probably produce a bit more pressure than your foot on the kick start.

[Blackthou]

Firstly, that's not a pipe, it's a work of art!

Path of least resistance I believe Dave is saying. By puttingf your finger over the pipe the oil can't take the easy option. By kicking the engine over the pump delivery rate is small in comparison to the engine running. WIth the engine driving the oil pump, not only will it return to tank but be of sufficient flow to circulate to other parts.

I always loosen the banjo bolts with the engine running after a to end overhaul just to be sure. Once I see it, I forget about it.

[chaz]

nice bit of pipe bending..
personally I would have kept the run as clean and smooth as possible. its something I was told as an apprentice, plumbing and electrical, to minimise bends and if you have to have them sweep rather than sharp, eases the flow and in the case of electrics reduces hot spots.
do you know if there is a restrictor in the return pipe?
The tee piece in mine has one end , the one closest to the oil tank is squashed in this increases the pressure to the rockers.

as Dave says, once you have proved the oil flows freely you can tighten and forget. hence when rebuilding cranks and oil pumps I squirt oil through the oilways to ensure they are clear and prime.

[Phil C]

Yes, I'm not really very happy about the shape of the pipe. Too many sharp bends, especially the W shape near the banjos. Might be asking for trouble.Thinking about starting again. Maybe I should melt the solder and turn the t- piece upside down, cut it to a stub, and use hose and jubilee clips ( as pauldemob suggested recently.) Decisions, decisions...

[Phil C]

Or maybe even make a bespoke one from scratch. Or maybe I'm getting a bit carried away.  Phil

[Phil C]

I've just stuck my finger over the return pipe hole, as Dave advised, whilst kicking the engine over with the banjos loose. Sure enough, oil dribbled from the banjos. Tightened up the domed nuts (over my kitchen gas ring-annealed washers) and the dribble stopped.  So that appears okay if the pipe shape doesn't cause problems. Phil

[Bess]

Hi Phil,
            The pipe looks great and too short to cause an issue, don't worry.

Best wishes...