Topic: What is normal oil pressure?

[Tom Stark]

I have a 74 750 that I just got running.  I have built LOTS of car motors, and am a bit of a gear head, not a newbe.  I have 60 PSI at idle, and it goes to about 80 before the relief valve kicks in.  I figure this is pretty good.  I just would like to hear from guys in the know with bikes, if this is just typical, or a little high or low.  Would find it VERY hard to believe it is low, so I figure average or maybe a little high. 
thanks for your time.
Tom

[Steve F]

60 psi at idle is good, assuming that the oil is still cold.  80 psi is typical for the higher rpm.  You may find that the pressure will drop to 10 psi at idle when the oil gets good and hot.  I use 20W50 with an oil cooler, and it still can go this low if you get stuck in traffic.

[snyquist53]

i just ran the same post a week ago.  i'm running some thin oil and my oil pressure at idle after it warms up is around 10 and it shoots up to around 30 to 40 while i'm running but the wierd thing is when i down shift it shoots up to 60 or 70.  it also seems to spike at random, which kinda worries me. i have only run it for small spurts of a couple miles.  i'm still scared to run it for a long time.

[andy750]

I checked this at the weekend when I was riding in 75 - 80F heat, running 20w50 in my freshly built motor of my CB750K4. I was getting 60psi when riding at 80mph and depending on how hot the motor was getting, dipped occasionally to 50 - 55psi. Ive noticed this before on previous trips (kong distance ones) and consider it fairly normal all things considered (oldish oil pressure gauge).

cheers
Andy

[HondaMan]

Honda's spec on the oil pressure switch is: the light goes OFF when the pressure rises to more than 50 PSI, and the hysteresis holds it OFF until the PSI drops below 10 again. This seems optimistic: I have tested some recently and found they turn OFF at 40 PSI and turn back on at 8 PSI, cold oil testing (hand pump).

If you add a little to these numbers, like 5 PSI, it should give you a good idea of normal ranges. My 750 runs 60 PSI hot at 4000 RPM with 10w50 and 75+ hot with 20w50. At idle, it can drop below 20 with 20w50 and under 15 on 10w50, particularly in heavy stop-and-stop traffic with long red lights.

One day I will find my "bearings-vs-oil-PSI" notes from long ago and publish them here. In general, though, the dry sump 750 pressures are much higher than the wet sump 500/500/350F/400F engines and all those "other" wet sump inline fours.

[Tom Stark]

Thanks for the replies.  With as hard a life as this bike had before I got it, I just wanted to be sure things were cool.  The only thing I did not do on this is build the engine, or trans.  Bike stripped down to bare frame, all new wiring, all sorts of things needed to be welded back onto the frame, (centerstand mount, side cover tabs, etc.).  Just about ready to ride.  Should have it on the road Friday.  I have some photos and an ongoing story about hte bike up at http://www.absolutetops.com/750Four/bike.htm  Need to update the photos and story, will do so in a few days.  Got the bike to run, static timed it, and adjusted the newly rebuilt carbs on the bench, and fired right over.  I still have to put on the new chain, (here now), and new sprockets, (on the way).  Hope to paint the tank, side covers, and rear fender Tuesday or Wednesday after work.  Right now will jsut do the black base coat/clear coat.  Will add the flames later.  Just need to ride it now! 
Tom

[maksuttt]

Honda shop manual for reference (i think oil is 10W40)

[kghost]

Not a honda number but........

Useful for Plain bearing engines in general.

If you have less than 10 psi per 1000 rpm it would be considered bad.

Up to the pressure limit....running anywhere from 60 to 90 depending on the engine.

10 psi = 1000 rpm
20 psi = 2000 rpm

etc

Just a general rule of thumb for plain bearing engines.