Motoscrubs.com

Meantime, I'm looking into measuring pressure at the crank axle.
I see some automotive oil pressure gauges switch as low as 0.1 bar, or 1.4 psi.
I don't know if that's not still too high.

I haven't been able to find a comprehensive catalog with all specs, including switch pressure point.
There is partial info here and there.

So I think my flow testing arrangement should work for pressure as well, just plumb a low scale gauge where I was suggesting fitting an open tube to a jug for flow, I think the pressure will be so low that it would'nt blow past the rubber seals on the bearing, but you would probably need to block of the primary gear feed drilling in the crank to stop any pressure loss there.

Cheers,
George

I made some photos and a video of a test to see oil flow from drive side crankshaft end.






Video:
https://youtu.be/5oyKRn_83P4

The driving primary gear is drilled to allow oil to flow to it from the big end bearing area. It happens against centrifugal force.
It was left as is.
I replaced the ball bearing in the clutch cover with a sealed type (after George's suggestion), and plugged the oil hole with a piece of O-ring, visible in the photo above the bearing.
That prevented oil from leaking away and allowed it to go outside the engine, where its flow could be seen.
The 8mm plug screw was removed from the crankshaft end.
An adaptor was made up to screw into the plug hole in the clutch cover, and a banjo attached.
A clear line was taken from the banjo and secured to the top triple clamp level.
With engine running oil flow in the clear line was almost immediate, confirming residual oil pressure even with feed to primary gears.
Only slow revs were tried so far. Later I'll do a high speed test to see what happens.

Well done! That is known as empirical evidence.

Hi Jordan,
Well done! nice to see an idea put into practice.......and your initial findings are pretty much what I would expect at low rpm, how ever the faster you run the motor the more centrifugal force will come into play (I think?) however as the revs go up so in theory will the flow/pressure so maybe this will overcome the centrifugal effect, really interested to see what happens at high/higher revs........great stuff
Cheers,
George

Excellent work Jordan, nice to see someone take up the experiment! It will be interesting to see what happens at speed when the engine is hot, I await with interest for updates!

Regards Nigel

Nice job Jordan, there was quite a good delivery, considering the low RPM, and the oil is still exiting at the primary gear, was that with a hot or cold engine? As Nigel said it will be interesting to see the result at high RPM when higher centrifugal force comes into play.
Working that one out mathematically is above my pay grade, accepted the delivery to a roller bearing is about flow not pressure, thinking about it logicically, the oil in the crank radial flow to the B/E is also under centrifugal influence, which in theory is assisting the flow into the B/E. Accepted there is oil escaping at the B/E bearing, but is the positive centrifugal input helping to overcome the negative force output to the primary gear ?
Your ongoing test's will hopefully answer the question.

The engine was cold.
It had no trouble getting as high as the top triple clamp.
It's easy to stop flow by closing off the end of the tube with a finger.
We'll see how high it gets when hot.
I'm thinking to ride the bike until nice and hot, then put it on its stand and do another test at higher revs.

I think "veloduke" Max had a good analogy of the situation, imagining a pipe with a hanging loop in it.

I think to be safe and not potentially cause a mess I would temporarily plumb your test pipe into a plastic bottle up at the top triple clamp rather than leave it open in case at higher rpm it hoses you down with lube
Cheers,
George

Wear a raincoat