1995 RK, with a 107" Sputhe motor, SS oil pump. Big cam, Branch Heads, big valves. Was running 20-50 HD oil, now using 60 wt. HD oil. All dino oil. On a cold start, Oil pressure will go up to 45 50lbs with a little throttle, or fast idle. But on a hot day, after a long ride, the oil pressure goes away and oil light will stay on even at 35mph (in 5th gear). I also have a pressure gauge, and it is at zero also. At about 50mph, it comes up to about 8lbs. My oil temp is around 175f to 180f at that time. Not getting any lifter noise, or any other unusual noise. I KNOW that EVO's run low at idle, but this is too low. I did a complete enging rebuild 2 yrs ago, and put the new SS pump in then. It is not hi pressure, or hi flow, just the regular pump.
Would a synthetic oil help prevent this? I have a V-twin 3 spring kit that is supposed to help, but I really don't want to start messing with spring until I get a better grip on what is going on.
Thoughts?
Steve

 

No synthetic won't help.
Either go with a heavier oil or rebuild your pump.

 

I agree with Texas, synth will do nothing to help. I have a 107" crate S&S engine and no idea what pump it came with, but it would be worth identifying which model of pump you have and checking with S&S if it is man enough for your engine. They have been very helpful answering my technical queries. Alternatively call Sputhe themselves.

 

My thought is you are lugging the crap out of the motor...can't be good for it.

 

He's already running straight 60 weight oil. I think his problem is well beyond thick oil. My Evo runs 13 lbs on 60 weight oil at idle and 105° ambient temp. I'd sure be checking that oil pump before you do start hearing noise. Then you'll be posting a build thread.

 

Not at all. Slowing down to 35 from freeway speeds. And light comes on, and stays on until I speed up. I never lug it.

 

With 60 weight you should have a lot more when cold and still atleast 6-10 lbs at idle.Tear it apart and check your clearances on the gears, your gonna need to either rebuild or replace.

 

I have a Sputhe set up on my 63 flh ie: electric ignition on the cam side and shovel heads. First start good pressure, when hot low oil pressure no valve noise. I know on the older bikes like my bike oil pump just correlates the oil its not a pump per say. Oil gets hot lower pressure this is something that was told to me. So I am interested in what you find out. Was going to take the oil pump apart and look it over but I think I will wait and see first.

 

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1963 FLH, Sputhe Shovel heads,5 speed trans one up 4 down, electric start, open primary, all belt drive, electric ignition, fast 93inch