oil pressuer on commandos

concours · Nov 23, 2014

kerinorton said:
I think one of the easiest checks is to take the filler off after any run you do and see that the oil returning to the take is satisfactory. I just checked mine a few minutes ago and gave it a rev, It nearly splashed oil out at me so much was being returned.
Dereck

A failed timing side crank seal would show normal scavenge flow, but with no oil pressure to the rod bearings.

kerinorton · Nov 23, 2014

That would be right. We are stuffed then eh.

Hobot · Nov 23, 2014

ah drereck, more seasoned Nortoneers open oil cap while carefully blipping and holding light and head off to one side for the likely over shooting of oil till fully satisfied. Oil fliters may not always filter but by golly they always flow even if clogged up.

kerinorton · Nov 24, 2014

so whats the answer to the problem of the oil seal in the timing cover shitting itself. Has anyone had the problem and how did they know they had a problem.
Dereck

JimNH · Nov 24, 2014

concours said:
kerinorton said:

I think one of the easiest checks is to take the filler off after any run you do and see that the oil returning to the take is satisfactory. I just checked mine a few minutes ago and gave it a rev, It nearly splashed oil out at me so much was being returned.
Dereck

Click to expand...

A failed timing side crank seal would show normal scavenge flow, but with no oil pressure to the rod bearings.

'Zactly! The best reason for a gauge!

auldblue · Nov 25, 2014

I spoke to Mick hemmings after I fitted a temporary oil pressure gauge about two years ago , holy shit Mick does not like them, wouldn't even talk about it. Even now two years on when I ask him anything about the bike ,he always says you've got one of them gauges fitted. No idea why he doesn't like them but it does show some odd readings to sat the least.Micks advice has always been first rate and he's easy to talk to, except oil pressure gauges.

J

Hobot · Nov 25, 2014

IIRC Norton has part number for oil pressure guage that was meant to fit tempoary for initial start ups to measure PV spring setting for cold oil then remove for real life. I'd guess the recoiling of Mick is its common for Norton not to develope the 10 PSI per 1000 rpm so likely had so many returns from his rebuilds he soon learned to hate oil gauges. Mr. Hudson also of same official Norton Service Notes opinion.

SteveA · Nov 25, 2014

hobot said:
Norton knew not to fit pressure guage so early on warned diistrubutors and owners not to. I can not find a reference to factory ever selling them.

Oil pressure gauges on Commandos tell you very little
If you read the appropriate section in the Service Notes you'll find the opinion that use of such a gauge is somewhere between a bad and terrible idea. Not only is it useless once the motor is warmed up, because most of the oil from the pump is doing its work on the bottom end and only a trickle is coming up to the rockers. If it breaks, you might not notice until you've lost your top end. John S. Morris (jsm@mediaone.net) on NOC-L 28th. Aug 1997

Click to expand...

Mr Hudson Service Notes quote that relates back to oil coolers.
OIL PUMP: The oil pump takes a long time to wear out, but when the mains go it's a good idea to recondition it, as
all those bits of bearing have to go through the oil pump on their way to the tank-full instructions are given for this
operation in the workshop manual. Usually, you'll be glad to know, no new parts are required. If you have changed
the cover, the gasket, or the oil pump, check that the little conical black rubber on the pump is just compressed-it
shouldn't be possible to push the cover quite home by hand. If the cover is very proud, check that there aren't too
many shims on the oil pump under the black rubber. They tend to stick together and not get noticed. For the hat few
years these shims haven't been used, a paper washer between the oil pump and the crankcase is used instead. I have
heard of engines which ran quite successfully for a while without the rubber seal-because somebody forgot it (no it
wasn't me)-the theory is that the centrifugal whirling of the crankshaft forces oil out into the big ends and draws oil
into the crank. The output from the pump is enough to drench the hole so that air isn't drawn in. No oil goes to the
rocker gear, though, as this requires pressure.
Mention of pressure brings me to another point-the fitting of oil pressure gauges. On the Commando (and for similar
reasons. most bikes) an oil pressure gauge is more of a liability than an asset. It is of necessity, fitted on the feed side
where any failure of pipe or gauge is disastrous to engine and rider--it's touch and go whether the engine seizes
before or after you fall off with oil on the back wheel. On the Commando this failure could be caused by engine
vibration in the same way that early rocker pipes failed. (We're coming to that.) The other reason that a pressure
gauge isn't much good is really twofold. At high speeds and high oil temperatures the pressure can drop to nothing
on the gauge because the pump can hardly keep up with the rate the stuff is flying out of the big ends. The
centrifugal force can keep the pressure at the big ends above the danger point, so there's no real panic--but the gauge
would inspire you with horror. Then of course if you did seize an oil pump by the time you noticed that the pressure
had dropped the big ends would have gone (. . . through the hole in the crankcase, with average N.O.C. luck!). If you
want an interesting gauge to frighten yourself with, but, which is inherently safer and can give useful information, fit
an oil temperature gauge in the oil tank. Let me know what it reads as you change into top for the Mountain Mile on
both the fourth or fifth lap! The latest Racing Nortons (we can't call them J.P. Nortons any more as they've stopped
the bikes from smoking) had a new type of oil pump-I wonder if this is because the ordinary pump can't keep up?

Now why didn't you just quote 'Mr Norton' in the first place Steve....he knew a thing or two....and says all you need to know on this topic right here.....

Any constistent pressure reading above the setting of the OPRV means there is a 'restriction' somewhere or the OPRV valve is incorrectly set....

The use of a OP guage is for maintenance, to check/set the OPRV, and identify other issues, i.e. wear! 0 OP when running at moderate RPM is not really good!

Put it back in the tool box when you are done.

acotrel · Nov 25, 2014

Matt Spencer suggested a good answer to the oil pressure gauge problem. Part he early oil pressure relief valve and the indicator button from a 50s Triumph twin fits in place of the domed cap of the Norton relief valve. I've been looking at gauges on the web, and there are digital ones for $20. However when you fit one and take the bleed from the rocker gear, you present another chance of failure. To my mind, it doesn't matter what the oil pressure is as long as it is there when the engine is very hot. Al I've ever done is look at the indicator button at the end of a race. On public roads you would usually have time to glance down at it now and then.

Time Warp · Nov 25, 2014

acotrel said:
Matt Spencer ... and the indicator button from a 50s Triumph twin ... On public roads you would usually have time to glance down at it now and then.

Perhaps it could be remote mounted in the seat foam. ?

kerinorton · Nov 25, 2014

Time Warp said:
There is also pressure induced scouring of the bearing surface but doubt that would happen on a Commando. (even with a minimal clearance)
Does the Commando crank run 0.001" per inch of journal ?

Most modern journals run 1 thou total clearance to 1.5 thou. preferably the 1 total thou .

kerinorton · Nov 25, 2014

Time Warp said:
acotrel said:

Matt Spencer ... and the indicator button from a 50s Triumph twin ... On public roads you would usually have time to glance down at it now and then.

Click to expand...

Perhaps it could be remote mounted in the seat foam. ?

And wouldn't that be a thrill.
Dereck

Time Warp · Nov 25, 2014

kerinorton said:
Time Warp said:

acotrel said:

Matt Spencer ... and the indicator button from a 50s Triumph twin ... On public roads you would usually have time to glance down at it now and then.

Click to expand...

Perhaps it could be remote mounted in the seat foam. ?

Click to expand...

And wouldn't that be a thrill.
Dereck

For some of the members I am sure it would be....

If I was that worried about oil pressure there might be a consideration given to a adjustable Hobbs switch fitment.
It could be wired to a light or buzzer.

I remember a 'Two Ronnie's sketch where a headset with a wooden rod came off the front with a light on it, I seem to remember it was to alert deaf folk to the telephone ringing but could be adapted to a crash helmet.
Of course you then have the chance of dismounting forgetting the wires running to the switch.
Its never easy in the land of Classic motorcycles.

oil pressuer on commandos

concours

kerinorton

Hobot

kerinorton

JimNH

auldblue

Hobot

SteveA

acotrel

Time Warp

.......back to the 70's.

kerinorton

kerinorton

Time Warp

.......back to the 70's.

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