how much idle oil pressure does an evo need?
Cruiser
Joined: Nov 2007
Posts: 216
Likes: 2
Typically most agree that very little pressure is required. In actuality, just enough head pressure to pump the oil up to the rockers, which is way less than a pound. The key is to have oil flow. My old Ultra has about 8 psi at idle on a hot day after riding awhile. With the original jetting in the carb, it would drop to 0 with the oil light flashing occasionally at idle. Now with it jetted richer, it runs noticeably cooler, and the pressure reads higher. I know these numbers are accurate as I tested my oil sender and gauge. My gauge actually reads 3 psi low, and my light comes on just about 2.5 psi.
Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
As a rule of the thumb you want about 7-10 lbs per 1,000 RPM's. However on a hot day and a slower than 950 RPM idle (you know, so that you can get that cool sound) you can get what looks like 0 lbs on your gauge. As long as the engine doesn't start making funny noises you should be OK, however we don't reccomend those slow idle speeds as it is not good for the engine.
Ultimate HDF Member
Joined: Jun 2007
Posts: 9,193
Likes: 494
From: Richmond, VA
May I chime in. Oil pressure is always a debated topic. The problem is so many people make intelligent arguements based on info they get from crappy gauges. Gauges like Drag Specialties, V-Twin, Harley-Davidson and the cheap asian copies, rarely if ever give accurate readings, and almost none of them are accurate over the entire band of temps. Once you get a decent gauge thats actually designed for an air cooled motrcycle, not a car, you can get reliable pressure readings. Harleys AWLAYS have some oil pressure unless they are busted. All you need is a gauge that functions properly at very low presssures our bikes make when they are hot. I put one of these on my Shovel years ago and its still going strong today. As a Lawyer, I learned early on to gaurentee nothing to anybody, but I gaurentee that you will like this gauge if you install it.
http://www.ertproducts.com/PROGAUGE.htm
http://www.ertproducts.com/PROGAUGE.htm
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Tourer
Joined: Apr 2007
Posts: 356
Likes: 3
From: VB, Virginia
i'm looking for an actual number on an accurate gauge. anybody know the spec for low oil pressure at idle when it should go into the shop for a bottom end or whatever?
btw, my pressure is fine.
btw, my pressure is fine.
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Ultimate HDF Member
Joined: Jun 2007
Posts: 9,193
Likes: 494
From: Richmond, VA
Yes, below 2 lbs with a gauge thats accurate.....is bad. But even thats relative. Since different oils in the same bike will produce different pressures at given RPM's or temps. What does your bike idle at? A high milage bike might only make 2psi with a thin synthetic 20-50 @ 950 rpm, but raise the idle and the same bike may then make 4-5lbs with a different brand oil @ an 1100 RPM hot idle. I would say if you can't get at least 2 lbs at over 1000 rpm hot, your probally not making enough oil presssure.
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Seasoned HDF Member
Joined: Aug 2007
Posts: 21,736
Likes: 17,577
From: Driftless Area
Mine is significantly higher after adding an oil cooler.
Before= 2-4 lbs. (HOT) @ idle. 15-20 lbs. (HOT) going down the road @ 3000 rpm
After= 12-15 lbs. (HOT) @ idle. 22-28 lbs. (HOT) @ 3000 rpm.
Before= 2-4 lbs. (HOT) @ idle. 15-20 lbs. (HOT) going down the road @ 3000 rpm
After= 12-15 lbs. (HOT) @ idle. 22-28 lbs. (HOT) @ 3000 rpm.
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Tourer
Joined: Apr 2007
Posts: 356
Likes: 3
From: VB, Virginia
that is very impressive! whats the longest you've rode with the cooler and down to 12 psi? what about the 2-4?