Oil Pressure Questions

My 74 Z1 has always had the oil light come on unless I "overfill" it with oil by about a quart or so.
I did an oil change a few weeks ago and filled it up with the "proper" 4.2 qts and fired it up last night to sync the carbs. The oil pressure light goes out on initial startup then comes back on after a bit and stays on. I put in another quart of oil and it's fine.

I put in a new oil pressure switch over the winter as well to rule that out. Does this mean my oil pump is bad? Or should I just accept mine likes a bit more oil in the crank case? I had the oil pan off a couple years back and the pickup screen looked fine, no blockage.

Also, I'd like to run an oil pressure gauge. What do you guys use? I know they are really low pressure and I'm having a hard time finding one.

HHmmm, this is kind of a puzzle. The oil level should have no impact on oil pressure; provided of course, there's enough oil to reach the pick-up and ultimately the pump????

Your oil pressure light should not come on even if your running 1 quart of oil. Adding oil should not effect your oil pressure uless you are empty. Are you sure you have the correct amount of oil when you fill it?

Yeah, that is what I was thinking. As long as there is enough oil to reach the pickup, there should be no issue? I put in the 4.2 quarts. I can measure it in the window of the crankcase with the bike level, but that never is enough to shut off the oil light.

Another thought....stuck open pressure relief valve? Or I saw where one guy had buildup inside of his screen, but again...oil level wouldn't matter.

With the correct level of oil ,
! when started cold is the light off , and once warmed up the light comes on ?
2 If this is the case is the light on only at idle ? Or does it stay on at higher RPM ?

Street Fighter LTD wrote: With the correct level of oil ,
! when started cold is the light off , and once warmed up the light comes on ?
2 If this is the case is the light on only at idle ? Or does it stay on at higher RPM ?

Cold start/correct oil....I didn't notice it right away...but I also was focused on syncing carbs at the time. But possible that it wasn't on at first.

If light is off after filling it up further to put the light out..... the light will come on after hard acceleration up through gears then go off after a while of normal RPM range.

Just so it is clear, you are running as much as 5.2 qts (= 4919 cc) of oil in a lower end designed to hold 3.7 liters (3700 cc) of oil?

Mcdroid wrote: Just so it is clear, you are running as much as 5.2 qts (= 4919 cc) of oil in a lower end designed to hold 3.7 liters (3700 cc) of oil?

Yes. Had a 5 qt container. Put in the 4.2=light. Put in the rest of the 5 qt=light. A bit more from another quart=no light.

I'm getting the feeling I'm going to be pulling the pan here in the near future to pull the pump out and inspect.

bLodi wrote:

Mcdroid wrote: Just so it is clear, you are running as much as 5.2 qts (= 4919 cc) of oil in a lower end designed to hold 3.7 liters (3700 cc) of oil?

Yes. Had a 5 qt container. Put in the 4.2=light. Put in the rest of the 5 qt=light. A bit more from another quart=no light.

I'm getting the feeling I'm going to be pulling the pan here in the near future to pull the pump out and inspect.

Although it is very rare for Z1 oil pumps to fail...you might want to inspect the pump. If it needs to be replaced, they are very inexpensive on eBay (because folks rarely have to replace them).

Ok, I just ordered another oil pump just in case (like you said they are cheap) and will dive in this weekend if time allows. Looking at photos of the pump...is it possible that the hole in the side also leads to the pickup? Maybe my screen is clogged and when I fill it up higher...it's getting to this hole and getting picked up?

Cant check pump from here but if your new to the bike here is a fyi

My bike has a gauge which reads zero to 15 psi
Starting engine stone cold pressure reads up to 15 pounds. Gauge acts like a tach as pressure bounces from 3 to 15 pounds while revving motor to keep it running till motor is hot , ( Turbos are real cold blooded and refuse to run smooth at a given rpm till warmed up.) Then settles down to next to nothing at idle when hot which makes my lite come on until I give motor some throttle which brings pressure up to 3psi and the lite goes back out.
Are you adding a quart of cold oil to your bike to over fill it which in its self might rethicken the oil and make the lite go off.
These motors rely on oil flow more than pressure
Hope this helps
Dave

I would insure that the light is working properly. If you want to verify there is no oil being pumped while the light is on. First fill the bike to the correct level. loosen up the main oil galley bolt located on the right side of the motor. I just hand tight it. Then start the bike. while the light is on, loosen the bolt and see if it shoots oil out. That will tell you if its pumping. If you don't get any oil, then I would remove the pan and inspect everything.