Might be low oil pressure

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Beemer

Beemer

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Well , being bored with to much idle time I put on an oil gauge plumbed into the rocker feed,
Motor is a 69 750 rebuilt with 4K miles. I have the fancy SRM relief valve, oil light, 20/50 Castro oil. Bike runs great and good oil return. My oil pressure is 40 at start up, after a 10 mile hard run I see 5 psi at idle and 18-20 at 4000rpm. My thoughts are to take a look at the cover seal and service the pump. Or just let it be. Any thoughts? Thanks in advance.
 
My 850 C shows similar PSI on the rocker line feed at same times. 40-ish at start ups, 5-10 at idle after a good run, and roughly 10 psi per 1k rpm during riding. Oil grade can make fair changes to these numbers.
Have also heard the oil flow is actually more important than pressure. So if you've got good return flow, you're good to go.
 
Possible rocker spindle flats are backwards installed in the head. Your oil pressure seems a little low at start. Should be around 50 to 60.
 
Have thought about installing SRM relief valve they talk a good talk, I'd put my old relief valve back on to just to see. I'd like to know results!!!!
 
60# on start up, a little higher when very cold.
normally around 18#-20# warm
maybe 10#-12# when really hot after a good run in the summer heat
SRM valve, big end bearing installed upside down, drilled rockers and guage feed off of left rocker hole.
 
If the bike is running fine and has good return to the tank then I wouldn't worry about it.
 
Mine runs very similarly to yours. I think sometimes after a whole day of riding the pressure is even lower. I have put about 20,000 miles on this bike with it running this way. The pressure is not getting lower, it was always like that. I don't think any wear is occuring on the big ends. Probably it could use some new big end shells. The main think is at normal road speeds there is pressure. Also there is no knocking sound. Badly worn big ends will give a double knocking sound.
 
SRM is set at 60psi, and that's what my gauge reads when starting cold. Many possible causes for low OP, from rocker spindles, to a worn pump, leaking timing side crank seal, and worn big end shells. First 3 are easy to check, add a dab of thread sealant to OPRV threads in the timing cover in front of the cross drilling when reinstalling.
 
baldy said:
Possible rocker spindle flats are backwards installed in the head. Your oil pressure seems a little low at start. Should be around 50 to 60.
Click to expand...
NOC Commando Service Notes: rocker spindles are fitted with the flats outwards -away from the holes in the rockers - because otherwise too much oil swamps the head. It doesn’t say it affects oil pressure.
 
With a failed timing cover to oil pump seal (MKIII) the return flow is excellent with zero pressure; I've had it happen twice - caught with a pressure gauge. My 60 psi gauge is pegged hard cold, runs about 40- 50 psi on a temperate day cruising but will drop, as I remember, to about 15 idling after a long highway run on a very hot day.

Failed seal dumps into the timing cover, it flows to the sump where it's duly returned to the tank having done little work.

Yes, I know I should have an 80 psi or higher gauge but what I attempt to do is to keep it off the peg - running slow until the oil warms up to avoid blowing another seal. I finally figured out that when the bike starts to wet sump, it normally doesn't, the seal has probably begun to split but hasn't yet failed.
 
illf8ed said:
NOC Commando Service Notes: rocker spindles are fitted with the flats outwards -away from the holes in the rockers - because otherwise too much oil swamps the head. It doesn’t say it affects oil pressure.
Click to expand...
It may not say the oil pressure is affected but having an open hole in any high pressure circuit does reduce the pressure in that circuit. This is both theoretical and confirmed in practice, a worn set of shell bearings reducing the oil pressure is exactly the same as introducing a hole.
 
Not to mention the PRV.
I would not like to see 20 PSI on a flat road on a cool day let alone in a high gear up a hill.

The oil pump has very narrow pressure side gears so there are limitations.
 
My old beaten on P11 has 60psi at cold start and 18psi at hot idle. I think mine is a little low. I'd prefer to see 23-25psi at hot idle. I have no idea what it should be. The conrods are still on the inside of the crank cases, so that's a good sign.

My 100psi oil pressure gauge is plumbed into the left front exhaust spindle cover. The gauge itself is up by my speedometer. I have 48psi or higher out on the road. I don't look at it that much when riding. Kind of a distraction. Actually considering taking the gauge off.
 
Tornado said:
My 850 C shows similar PSI on the rocker line feed at same times. 40-ish at start ups, 5-10 at idle after a good run, and roughly 10 psi per 1k rpm during riding. Oil grade can make fair changes to these numbers.
Have also heard the oil flow is actually more important than pressure. So if you've got good return flow, you're good to go.
Click to expand...
Mine is pretty similar.

Motor was rebult by probably the best builder in NZ about three years ago now. No fancy OPRV. Drilled spindles and take off to the guage from the spindle plate.
 
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