XJ550. How much oil pressure should I have?

Does anyone know what oil pressure I should be seeing from a 550? My shop manual says the bypass valve opens at 14psi but that sounds a bit low to me. Maybe i'm not understanding how the bypass valve works?

 

Their terminology is a bit foggy, so I'm not 110% sure;

however, the RELIEF valve opens at 72psi. I'm pretty sure the bypass valve just bypasses the filter; the relief valve "pops" at too high of an oil pressure.

None of the manuals says squat about "normal" or expected pressure.

 

I've heard it's really - REALLY low at idle, like 10 PSI,
which would scare anyone familiar with hot-rod V8's, where I've seen 70PSI at IDLE on a cold motor. (a few times)

I've never measured a bike.
Maybe someone here has ??

 

The XJ motor uses oil "jets" for cooling as well as lubrication. As such, the oil pressure is vastly different depending where in the lubrication system you take a pressure reading; the large passages and galleries will have little or no pressure, as the passages and orifices get smaller the pressure increases.

Take a good look at the lubrication schematic in the back of your factory manual.

Where to take a reading?

This might be a clue: http://xjbikes.com/Forums/viewtopic/t=40711.html

 

I'm going to do some more research on this. I did find a few sites that show as low as 8psi at idle on some modern yamaha bikes. Per another website the XS1100 pushes around 40PSI when at 55mph in top gear. The oil light comes on at 4psi so 10psi at idle could be valid. I'll see what I find out.

 

The whole family of motors are pretty similar; and the 550 and 1100 are the most highly-stressed of the lot, because of their positions at the extremes of the displacement scale. As such, both are pretty unique unto themselves, as opposed to the 650/700/750/900 family.

An oil pressure "operating range" of 10psi ~ 40psi sounds quite reasonable.

Remember that the 550s have an oil pressure operated primary chain tensioner; and that it's a "true" primary chain in that it provides the drive from the engine to the clutch/transmission. (The big bikes have a gear-driven primary, their jackshaft chain only drives the alternator, and is driven by the starter.)

So again, the oil pressure being read will greatly depend on WHERE the reading is being taken, and on what motor, and under what conditions. Unfortunately, the only really solid answer for you will have to come from a 550. The shafties are built and lubricated differently; and the 1100 is different than the whole 650/700/750/900 genre.

Fun, huh? Keep us posted.

 

Hold on - -
The XJ's oil light goes on due to LOW oil LEVEL -
not pressure related.
*and*

the best place to take the "blood pressure" is just after the filter. and before any of the bearings. This would be the maximum pressure the motor would see.

 

I had a talk with a friend of mine. Now I understand why I was confused by this. The 14 psi filter bypass is based off differential pressure and not total pressure. For example, if the pressure into the filter is 40psi, the bypass won't open unless the pressure out of the filter drops below 25 (due to a blockage in the filter).

1986 FJ600 11.4psi, 1200rpm, hot. The same manual says it should stay below the relief valve value when reving. So my guess on the XJ550 would be around 10-12 at idle and up to 60 pushing high rpm. I plan to tap a set of sending units into my oil cooler plate so i'll report my findings

 

the po of my 550 was going to put the engine in a 4 wheeler as well, that f***er must be pretty quick!

 

I got my motor out of a 550 that must have sat outside for more than 10 years. The top covers on the carbs were rusted off. Old grass/leaves had been sitting on the motor for so long that they decomposed back into dirt. The wiring harness was also eaten by mice. Other then that it was in good shape.


I cut my thumb pretty bad so no garage time for a another week or two.