oil light

Joined
Sep 8, 2007
Messages
33
Country flag
Just bought a '73 850 commando, the oil light (red on head light) is staying on, how do I confirm I am getting flow?
Thanks,Larry
 

L.A.B.

Moderator
VIP MEMBER
Joined
Nov 20, 2004
Messages
17,998
Country flag
Larry said:
Just bought a '73 850 commando, the oil light (red on head light) is staying on, how do I confirm I am getting flow?

The 'red' light is not an oil pressure warning light. There is no oil warning light on a Commando as standard.

It is a charge control warning light.
So should go out when the engine is running above idle speed, so either the assimilator is faulty (quite common) disconnected, or not connected correctly? Or there may be a problem with the charging system? You may need to do some electrical checks to confirm this. Does the headlight brighten slightly when the engine is revved off idle? If so , there may not be any problem with the charging system.
 
Joined
Mar 11, 2006
Messages
98
Larry said:
Just bought a '73 850 commando, the oil light (red on head light) is staying on, how do I confirm I am getting flow?
Thanks,Larry

Just in case your worried about your oil as well. Take the cap of the oil tank when the engine is running and you will see the oil jetting out of the return pipe back into the tank.
 

L.A.B.

Moderator
VIP MEMBER
Joined
Nov 20, 2004
Messages
17,998
Country flag
mike916sp said:
Take the cap of the oil tank when the engine is running and you will see the oil jetting out of the return pipe back into the tank.

That certainly would give an indication of oil flow, at least in the scavenge side of the system, and also an indication of feed flow if a long enough watch of the oil return is maintained. However, evidence of 'oil flow' is no actual guarantee there is adequate 'oil pressure' which of course is important, low pressure from worn big-ends, the relief valve stuck open, rocker spindles orientated the wrong way or a leaking crankshaft seal would all reduce oil pressure but without having any affect on the oil flow rate.

So a check of oil pressure with a test gauge would give a better indication that the lubrication system was working correctly, in my opinion, although as this is a case of 'mistaken identity' -the red warning light not being anything to do with the oil system there is probably nothing wrong with the lubrication system anyway..
 

Ron L

VIP MEMBER
Joined
Feb 27, 2004
Messages
3,111
Country flag
Keep in mind that in an engine with roller (or ball) bearings, oil flow is more important than oil pressure. An oil pressure gauge at the rocker arms will give the uninitiated some heart palpitations. When the oil is hot, the pressure can read as low as 2-3 psi at idle and only 15-20 psi at speed.
 

L.A.B.

Moderator
VIP MEMBER
Joined
Nov 20, 2004
Messages
17,998
Country flag
Ron L said:
Keep in mind that in an engine with roller (or ball) bearings, oil flow is more important than oil pressure.

As I see it oil pressure is just as important if not more so, as the big-end plain bearings (and valve gear) are what is actually supplied with both flow, and hopefully, pressure, from the oil pump.
The main bearings rely on splash feed only. The big end bearings being far more likely to suffer first from any lack of lubrication pressure/flow than the main bearings, in my opinion.
 

Ron L

VIP MEMBER
Joined
Feb 27, 2004
Messages
3,111
Country flag
I don't disagree, it is just that on a ball/roller bearing engine, maintaining that pressure (because of that splash/squirt lubrication) is like trying to keep it in a tea strainer. If you could tap an oil pressure gauge between the pump and crank, you would see more normal pressure. However, by the time the flow gets to the rocker feed, much of the pressure is lost.
 

L.A.B.

Moderator
VIP MEMBER
Joined
Nov 20, 2004
Messages
17,998
Country flag
OK Ron L, only your initial reply appeared to suggest that oil pressure in a Norton Commando engine was of little importance as it was a ball/roller bearing engine? That's how I read it anyway, and I suppose could have been taken by others to mean that literally?
 

Ron L

VIP MEMBER
Joined
Feb 27, 2004
Messages
3,111
Country flag
Yeah, it was not very well stated. I guess I should read what I write before I send it!
 
Joined
May 22, 2004
Messages
522
Larry ~

My alternator failed in peak hour traffic in Brunswick in Melbourne in 1996!
Well the battery expired.. but the Gods were looking after me as the bike conked out 500 feet from Union Jack Motorcycles.. ( Now tell me that was not divine intervention!)

AND there was no red light warning.. after the stator was replaced ~ I continued the journey and 600 miles down the highway the red came on ~

And as L.A.B. suggested the lights increased with revs ~ so in short I pulled out the assimilator and bounced it off the nearest wall !! (The aluminium can in the spring coil .. make sure you don't remove the trafficator can by mistake ! :lol: :lol: )

The bike still runs just fine ~ in fact never misses a beat !!
 
Joined
May 13, 2007
Messages
4,153
Country flag
Stuart SS said:
My alternator failed in peak hour traffic in Brunswick in Melbourne in 1996!
Well the battery expired.. but the Gods were looking after me as the bike conked out 500 feet from Union Jack Motorcycles.. ( Now tell me that was not divine intervention!)

AND there was no red light warning.. after the stator was replaced ~ I continued the journey and 600 miles down the highway the red came on ~

Bummer. In my experience the warning light assimilator is pretty reliable, though of questionable value. It's just a relay connected across the alternator winding ahead of the rectifier. Theory is that if the alternator fails (below about 6vac) the battery will illuminate the warning lamp.

I've had it in mind to design a solid state replacement that actually senses charge current. Maybe some day...
 
Joined
May 22, 2004
Messages
522
Maylar
I think there are solid state units available (?)

LAB ~ yuor link did not open ~
 
Top