Topic: Oil pressure question - cb750

[macvit7906]

Happy 4th everyone!

Getting prepared to start my rebuilt engine this week. A few months ago had 60psi oil pressure on a bench test with the starter cranking the engine.

Got the engine in the frame.
Had to re-prime the oil pump because of an air lock (tipping engine to get into frame) - pump wasn't taking oil

after re-priming, the pump takes oil but only reading 20 psi on the oil pressure gauge - visibly getting oil to the top end.

Same oil pressure gauge, same starter. What could cause the 40 psi drop in oil pressure from bench to engine? The only change I made was from 10w-50 to 10w40 oil.

Theoretically, the  oil pressure should get higher with higher RPMs correct? Am I safe to do first start up in this condition or should i try to get 60 psi on the starter first?

[Jerry Rxman Griffin aka MuthaF'er]

You have pressure. The starter is not that strong. Fire it up. Watch it pop to 70psi.

[ekpent]

 Those first start-ups are always a little fretful but rewarding. Seems my projects never have a pressure gauge but I always look into the oil tank with a flashlight right away checking for good circulation,bubbles and other good stuff. Good Luck when you hit that button !

[macvit7906]

Appreciate it guys. I guess I'll just fire it up.

Just bothering me that there is a 40 PSI pressure drop from bench to frame. Could switching to 10w-40 oil do that?
Also i suppose the temperature is warmer now compared to when i did the bench test.

[Bowswell]

I use 20/50w and cold 60lbs and hot engine it?s 20lbs in idyl.