All Sportsters have oil pressure, even Ironheads. It's also been said that putting an oil gauge on an ironhead is useless due to the low oil pressure they operate on. However, most Sportsters operate off low oil pressure especially during hot idle.
The first answer is just to rely on the oil light. But also checking oil pressure will tell you more about the health of the oiling system. An oil gauge can be fitted to any Sportster to accurately measure the pressure against the specs in the respective FSM and then removed if desired.
When checking oil pressure, it's important to note that you are not testing pressure at a dead stop standpoint (as in a dead end of pipe). The oil is flowing into the engine at the same time you are testing from the test site. And the resulting pressure reading is a reflection of current pressure near the source WHILE oil flows downstream and out from there. Oil pressure will be lower downstream of the oil pump depending on the restrictions in the oil path and how big the outlet holes in the top end as well as the pinion to flywheel path.
Rocker box oil pressure (Evo).
Evo Oil pump pressure does feed up into the rocker arms via the lifters but is heavily restricted by the path through each lifter and slightly restricted further by elevation.
Cam cover oil pressure (All).
Oil pump pressure is always present internally in the cam cover with the engine running.
That is also a deceiving statement. Pump pressure runs through internal cavities in the cover to get from the top to the bottom of the cover and to the pinion shaft.
However, oil pump pressure is confined internally in the cover and does not pressurize the cam chest.
Click Here to view “Installing an Oil Pressure Gauge” in the REF section of the Sportsterpedia.
ALL PRESSURE SPECS IN THE FSM ARE FOR HOT OIL (at operating temp).
For an accurate reading, run the engine until the oil reaches normal operating temperature (ride at least 20 miles at or above 50mph first).
Compare pressure reading against the expected figures in your respective FSM as in below:
As tested with hot oil and a gauge mounted off the oil pressure switch location at the oil pump; The oil pressure switch has to be removed for the gauge to be installed. Oil filter is on the return side of the oil pump and should not hinder pressure reading. |
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Year Model | Minimum | Normal Riding Conditions | Max Riding Conditions |
1957-1969 Sportsters 1) | 3-7 psi (idle, with spark retarded) | 10-14 psi (6 psi at 20 mph) | |
1970-1978 Sportsters 2) | 3-7 psi (idle) | 4-15 psi | 15 psi (60 mph in high gear) |
1979-1985 Sportsters 3) | 4-7 psi (idle) | 4-15 psi | 10-20 psi (3500 rpm) |
As tested with hot oil and a gauge mounted; 1. Off the plug hole on the engine case between the tappets; 2. Off the oil pressure switch location at the oil filter pad. Oil filter is on the feed side of the pump giving higher pressure on the pressure gauge. Note: Oil pressure will be lower when checked between the tappets but the FSM specs use this hole for testing. |
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Year Model | Minimum | Normal Riding Conditions | Notes |
1986-1990 Sportsters 4) 5) 6) | 1-7 psi | 5-30 psi (2500 rpm) | tested from plug hole between tappets. |
7-17 psi | not specified | tested from oil pressure switch location at the oil filter pad |
As tested off the oil pressure switch location at the oil filter pad. Oil filter is on the feed side of the pump giving higher pressure on the gauge. |
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Year Model | Minimum | Normal Riding Conditions |
1991 Sportsters 7) | 7-12 psi | 12-17 psi (2500 rpm) |
1992-2004 Sportsters 8) | 7-12 psi | 10-17 psi (2500 rpm) |
2013 XR1200X 9) | 16-20 psi | 40-44 psi |
Has oil pressure relief set at 50 psi. 10) Includes an oil cooler w/ thermostat opens at 190ºF (88ºC). |
Installing a gauge at the rocker box is basically useless in diagnosing from the FSM.
There are no specs in the manuals to support any readings taken from the rockers.
Oil pressure will most likely be measurable on startup but low to nil when the oil gets to operating temp.
However, below are some noted pressure readings from XLFORUM members.
A 0-15 psi gauge (although it will max out with a cold motor) will give you the most accurate readings with hot oil. 11)
A 0-30 psi gauge is only useful at cold temps.
A 0-60 psi gauge is useless when testing from the rocker box.
All of this depends on the oil you are running also.
Multiple viscosity oils will show low to no pressure at running hot or cold idle.
50 wt in the summer shows lower pressure while 60 wt.
Other XLF member results noted from the rocker box:
When a problem is suspected, it helps to have a reference graph against which to compare the results. 13)
It is, therefore, advisable to map an engine shortly after it has been run in, and then use this baseline for comparison with later graphs.
Any change or drop-off in the graphs should be investigated.
First, check the pump (and pressure-relief valve if applicable).
If no fault is found with the pump, the engine itself should be inspected for excessive leakage.
A chart similar to the one below can be used to keep up with successive pressure readings.
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