KH Over Oiling - a different question

[SteveHands]

Thanks Nev. Luckily it’s a steel pump so no worries there. I’ve never used running-in oil either but I’ve never had a KH before either!
I’ve now got the rockers fed from the return side so the original feed now just goes to the gauge, which now shows 100psi when first started up.
The biggest reduction in smoke occurred when I added a non-return valve to the breather. There’s definitely not one in the breather/pump drive fitting despite what the manual says and Drags listing one!
I think you may be right about the relief valve, I was suspicious of the weedy spring that was in it originally and replaced the whole thing with new from Drags. Their spring was much stiffer so maybe it’s too strong. I shall make another test rig and compare the two and report back.

[Paul Slootheer]

100psi When cold is very good! My former KH’s also showed 100psi cold, and aprox. 60-70 on working temperature. Idling they gave aprox. 20-25 when hot.
I’am surprised there was no breather! I guess because it was absent this initiate the smoking?

[SteveHands]

The breather is just a hole in the top fitting of the oil pump drive shaft. There is a ball bearing in it but it’s a thrust bearing, not a one-way valve as described in the handbook. Maybe earlier models had a valve.

[nevhunter]

You don't NEED 100 Psi any time. It will load up the skew drive gear as well and put end thrust on a camshaft . 50-60 PSI should be ample oil pressure. The RELIEF valve should do it's job. Some breathers could be inadequate and cause oil leaks. A thin metal disc is the best flap valve in a breather as it has little mass. It doesn't require a spring and only moves about .030" and it will be audible when Idling. Properly designed it will even provide Negative pressure.(also prevents DUST going in when idlling). Nev

[Paul Slootheer]

100psi in my case was just for a ample few minutes when stone cold… nothing to worry about. In practice it will settle down very quickly in the region of 60-70psi which is a very healthy figure imo.

[Chris Sealy]

I found that when I fitted a Draganfly supplied oil pressure relief spring to my Mk1 squariel. The oil pressure gauge, which I had checked for accuracy, registered 105 psi. As Nev says, this will stress the skew gear; and also the pump itself. It probably isn't good for the big end and plain bearing journals either.
My solution was to cut a single turn off of the spring, then bend the end of the spring inwards to stop it from winding itself passed the split pin.
It now registers 60psi cold, which I believe is safer all round. I read somewhere that even race car engines use the rule of thumb, 10psi per 1000rpm.

[Paul Slootheer]

I would agree when oil pressure would be maintained on 100psi, but thats not the case. This figure is only reached when the engine is started from stone cold, but it will drop quite quickly to the region 50- 70 (riding condition, and depending which viscosity…) Starting a cold engine with shell bearings, (like a KH) causes most of the wear. This is a general assumption. Firm oilpressure for these moments (starting) would be beneficial in my opinion.

[nevhunter]

If you rev the engine straight away you MIGHT damage a bearing. Its grit that wears bearings. It's NOT safe to achieve those high pressures. It's loading things too much. The days of running race engines at high oil pressures are Long Gone. Nev

[Paul Slootheer]

It seems every now and then insights on specific subjects change for some reason. When you start for example a topic about oil (no don’t do it, stay away) dozens of opinions will show up. Some more convincing than others…

But to stay on topic: did sorting out the breather reduced the over oiling?

[nevhunter]

IF you read about oils on line you are entering really WEIRD territory. There is a very wide range of Offerings available, Probable very few specifically for Our motors.The Camshaft lobes and followers are the Most critical surfaces to lubricate and High Local temps a big consideration. I don't consider ALL oils are the same. Best oils could cost More but it shouldn't be outrageous. Cat. converters make some additives non permissible so think on that. I have run Aero engine oils. 100 equals 50 weight.