Oil pressure

Anonymous

Guest
I recently fitted an oil pressure gauge on my 72 Commando, connected it to the left hand rocker box fitting. The oil pressure is 10-15 psi, and it does not change much from cold to warm or with varying rpm`s. The bike suffers from wet sumping, so I am quite sure the oil pump is worn. Assuming the gauge is OK, is there anything I can do to the oil pump to make it seal better (besides changing it out)? I have heard about "lapping" the pump, what does that mean ?

Thore
 

Anonymous

Guest
Thore,
If you are confident the gauge is working properly, how many miles are on the bottom end? The gauge on my 850 hot rod will give me 60-65 psi when cold at anything over 2500 rpm and 15-20 psi at idle. When hot, this goes down to about 40 psi over 2500 and 5-10 at idle.
Since you are measuring what is sent to the top end, worn rod bearings could bleed the pressure from a well working pump before the oil (and pressure) reaches the top end.

It's simple enough task to pull the pump and disassemble it. Once done, the end plates should have any gear marks ground flat again and the rotor gears should be checked for damage and should be flush with the ends of the pump body. Be sure to seal the pump to the crankcases with a gasket and maybe some gasket cement to minimize wet sumping.

There is a better description of the procedure in the factory shop manual, available from most Norton parts dealers and a worthwhile investment.

Ron L.
 

Anonymous

Guest
Thanks Ron - where did you fit your gauge ?

What puzzles me is that the pressure stays more or less the same. I have no decent drawing of the lube system - is there a better place to put the gauge than on the left rocker feed ?

Thore
 

Anonymous

Guest
My gauge is tapped off the banjo for the cylinder head oil line at the timing cover. I don't know that it should make any difference if it is at the head or at the timing cover. The only place that oil pressure is really important in a Norton is at the rod bearings. Just how you configure a gauge to measure that I don't know. The gauges we use really only tell us that there is some oil flow, as the end of the cylinder head oil feed is at the rocker/rocker spindle bearing surface which is not really designed to hold pressure.

I am forwarding to you a copy of the lubrication system offline. Maybe that will help.

Ron L
 

Ron L

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Thore,

If you send me your e-mail address I'll forward you that lubrication diagram.

Ron L
 

Anonymous

Guest
I would be very grateful if you did !

My e-mail address is hs-berg@frisurf.no.
So what you are saying is that 8-10 psi at the rocker feed isn`t too bad then ?

After all, the oil has passed most of the pressure drop zones and there is not much left after the rocker box to cause any pressure read-out.

Regards, Thore
 

Anonymous

Guest
Thanks for the mail, Ron. It came out just fine. I tried to send you a reply but it got bounced by your e-mail server.
 
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