R65 Oil Pressure

[Bob_Roller]

Considering installing an electric oil pressure indicator on the '81 R65 .

Anyone know what kind of oil pressures these bikes have ?

The set-up I'm considering has 80 psi as it's highest graduation marking on the indicator face, I'm not sure if this is high enough .

I keep 20w50 oil in the bike all year long, and I'm sure during the colder temperatures, the oil pressure is quite high on first 'cold' start of the day .

[Justin B.]

I don't think 80 psi will get it as I think I've read they run north of 90.  I was looking at 110 psi gauges once upon a time so maybe I read something that made me think that would work.

[Bob_Roller]

I think I'm going to go with a 150 psi indicator, that's the highest range that VDO has .

I thought I saw something in print, that in cold conditions, 160 psi on start-up wasn't uncommon .

This may explain the crushed oil filters .

[Barry]

Doesn't the pressure relief valve open at 75 PSI to limit the oil pressure. It will still rise a little above 75 psi but I don't know by how much. Psychologically I would want a gauge to read at least 2/3rds up the scale at normal running pressure.

I have an oil pressure gauge in the car and it maintains the max 3 bar hot or cold presumably due to the pressure relief valve or maybe the gauge is against the stop. Either way it comes to no harm.

Our bikes have a high performance oil pump hence the concern about collapsed oil filters if the pressure gets too high.  I read that when airheads were raced the oil pump was redesigned for reduced output as it consumed several horsepower at high revs.

[Bob_Roller]

I posted this on Boxerworks, and the only response of real world information was, about 100 psi on cold start-up, around 80 psi at normal running speeds, and around 40 psi at idle .

So if your low oil pressure light comes on, it's set to activate at about 7 psi, you've got problems .

[Barry]

Those figures sound realistic.  

It makes you wonder though why the switch that operates the low oil pressure light is set so low.  By the time that light comes on the damage could be already done - which is where you came in with a gauge.

[Bob_Roller]

I did some research on oil pressure sending units, and the average range for low pressure switch activation, seems to be in the 7-10 psi area, this is for VDO parts .