Why such low oil pressure on these motors

[Grisolm1]

I have a Drag Specialties liquid filled gauge installed by the PO with tap in usual place near the clutch. Pressure is within spec per the yammy manual so I believe it to be normal but as some of you know it's essentially 0psi with a hot motor at under 2k rpm. I have to assume it's reading the other side of the relief valve or something.

 

Any of the experts here know why the readings are so darned low on a warmed up motor?

[dingy]

Attached are the lubrication routes for the 1st gen motor, would think the 2nd very similar.

 

It isn't real clear as to what circuit the side plug is in.

 

Page 8-23 appears it is on the line that feeds the cams.

 

Have a similar gauge mounted on scooter, haven't got bike running yet this year due to medical problem though. Shown in one of the pictures mounted on a VMax.

 

Gary

Edited June 22, 2011 by dingy

[Condor]

What weight oil are you using?? Around here I go to 20w50 during the hot months, and 10w40 during the winter.

[Grisolm1]

Mobil one 15-50 is what PO used and he gave me a jug for next change. I usually use Rotella synthetic in the blue bottle and will plan to for my future changes. Oil pressure is quite high when cold and again is within yammy specs so I think (hope) this is normal.

 

My gauge is very similar in type and install to Dingy's.

[Squidley]

They run about 5 lbs of pressure when the engine is hot and at an idle. The 1st time I saw a gauge with that pressure I had a bit of a pucker. Once your running down the road it runs up to about 30 lbs. Believe it or not, the big 3 did tests on oil pressure and 5 lbs of pressure is sufficient at an idle to keep the engine properly lubricated. Guaranteed Yamaha wouldn't offer a 5 year warranty on the bike if they believed the 5 lbs at warm idle wasn't sufficient. Old gearheads are just used to seeing 30 lbs warm oil pressure at an idle....

[Bubber]

I too have very low oil pressure when it is warm. Don't off hand know the brand name of the gauge. It is mounted on the handle bars and I just thought that, that may have something to do with it. Because the oil is not evident in the upper part of the clear plastic tube. I assume that it drains back to the engine when not running. I have been told more than once that the bike has a idiot light for oil pressure and if it ain't on you are good to go. I once suggested that a mirror be used to view the oil sight glass when sitting on the seat. And I got an ear full about the idiot light and there was no need to have a mirror to see the sight glass.

I have always followed that advice with out problems. So take it for what it is worth.

Let us know what you find out.

[Stache]

I once suggested that a mirror be used to view the oil sight glass when sitting on the seat. And I got an ear full about the idiot light and there was no need to have a mirror to see the sight glass.

 

 

I guess I'm old fasioned. Lights fail. Sensors stick. My buddy has a mirror rigged to his sight glass on his 1100.

 

I take a look at the glass every time I check the tire pressure, once every 2-3 days. Don't want to give MaYamaha an excuse if something goes wrong. "The oil level is low - when was the last time you checked it? That's what caused the failure, lack of rider maintenance, so it's your fault - no warranty coverage for you..."

 

For the amount of time it takes, it don't hurt. I pull the dipstick out of the truck and the car occasionally too.

[saddlebum]

There are many engines that run on what appears to be low oil preasure detroit two stroke diesel was one example big as it was it only ran between 5 and 10 psi. at idle and as little as 20 psi at high rpm. This was because they ran low preasure, high volume pumps. I suspect our engines may do the same. At MD I questioned V7Goose about the idiot light, Because mine would on the odd occasion come on under hard accelaration. He told me that the light is an indicator of oil level not preasure.

Edited June 22, 2011 by saddlebum

[V7Goose]

Yes the stock idiot light is a level light, which I think is a great idea. And it does occasionally flash on hard acceleration, especially at high RPM and going up hill (this is even documented in the owner's manual). BUT, that oil level light does not come on when sitting still until you are WAY low on oil, so checking the sight glass regularly is still a good idea.

 

The most value that the idiot light has is if it comes on briefly after a cold start (when the oil is still thick and not draining back down as fast as usual) or you happen to notice it is flashing more than usual during acceleration - that would indicate your oil level is going down, so better check into it. And it has no value at all as a level indicator with the engine not running.

 

And as others have already said, the typical 5 lb oil pressure at idle is normal. But I also believe this is a prime reason that Yamahaha specs the idle speed for this engine at 950-1050 RPM. I believe that it is IMPORTANT to set the idle correctly. Most of us prefer the way the engine sounds and idles at a much lower speed - the average person setting it by ear will leave it idling around 650; considering the low idle pressure, this is NOT a good way to set the idle! If you do not have a tach, find someone who does and compare the sound of your engine to theirs at the proper idle speed.

 

If you must set the idle by ear, I strongly suggest you first set it where you think it sounds about right, then crank it up more. Even then, you will probably still be under 1000 RPM.

Goose