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First you need proper testing equipment to yield correct results. I agree with anyone giving sound reasonable procedures. I haven’t seen any in this post yet that fall outside of those guidelines. The diagnosis process is to eliminate parts of a system to come to a solid conclusion of what has caused the current issue.

You could drain the oil and depending on your comfort level, you can inspect the oil or send it out for testing, to look for excessive bearing material. It might give you a better look inside. if it looks clean then you might at your discretion run the bike. In a perfect world you could drained the oil, heat the block, heat the oil to operation temps. Put the oil in the engine and run a quick pressure test. Maybe someone has a better idea. Just error on the side of caution and consider the worst till you find different. In life it’s always best to prepare for the worst but hope for the best. 

Do you think this kit will give me a more accurate reading? It tops out at 140psi vs 300 on the one I was using before. 

www.harborfreight.com/engine-oil-pressur...fnmOmqRoC7D0QAvD_BwE

 

I suspect the pressure regulator is faulty.
Steve

Based on your earlier testing, it seems like the relief valve and pump are working when the oil is cold.  The focus should now be to measure the pressure when the engine is warm, when the light is coming on, and make sure it's in the 28-36 psi range.  This is the range you really care about, so I would find a gauge that would give very accurate readings over this range.  For this task a 50 or 60 psi gauge would be better than a 140 psi gauge, even if you wouldn't be able to use it to measure the cold pressure.

Mikaw's suggestion for oil analysis is a good one.  I have used Blackstone Labs many times and their reports and comments are very useful.  If you write a detailed note describing the issue you are having and what you are looking to get out of an oil analysis, they generally will provide a detailed response based on the results.

www.blackstone-labs.com/

Regarding further testing, I would be inclined to replace the oil filter with a new one, maybe a different brand, and see if that make a difference, ideally by measuring the pressure with an accurate gauge.  I'm not sure I would try to run it without a filter, simply due to the complexity of the process of getting it into that state (hot and no filter).

Another thing that might be good to do is remove the cam shafts and check the cam bearings.  If the engine is really starved for oil, you might see damage on these bearings.  You could also measure the bearing clearance with plastigauge while you have them out.  Cam removal is often part of a valve adjustment, so it's generally not a ton of work to do.  If you have a problem with the crank or rods you may not see any issues in the top end, so it may not answer your question at all.  But if you do find a bearing issue you'll know that you shouldn't continue to ride it.

 

I would drain the oil into a clean pan for a later reuse. Remove the oil pan, remove the oil pump, dissamble  the oil pump and visually inspec the pump internals.
A weak oil pump can build up oil pressure in cold condition (low viscosity) but not in hot condition (high viscosity).
A weak oil pump and/or clooged oil pump screen can´t suck hot oil out of the pan and can´t build up oil pressure!!!

No eBay APP ID and/or Cert ID defined in Kunena configurationIf your a minimalist, who dosent want to aquire many tools. Replace the pressure switch and see if that keeps the light off.
On the other hand, If you like to experiment and like having tools, Get the HF gage set, but add a 0-60 gage.



You can ride with the gage attached and verify the pressure the light comes on at.
 

Just a short story form my first Z1 engine rebuild i did 20 years ago. I disassemble the oil pump for a inspection (all part are good) and bolt it back into the engine.
On the first ride when the engine oil warm up, the oil pressure light came up flickering on idle but not on high rev. Long story short, had to remove the oil pump because i forgot to tighten up the oil pump housing screws to the correct torque. 

I took apart my oil filter assembly yesterday and realized that it's missing a washer (92022). Could this be contributing to my issue?

Doubtful. I think it’s only mission in life is to protect the rubber seal on the filter from getting gnawed on by the spring. I inadvertently  ran without one with no ill effects.

Replaced the oil filter and checked pressure with my new gauge, which read 70psi cold. Went for a 30 minute ride and the oil light did not come on. Got back to my garage and checked pressure again, came out to about 30psi warm. Still no oil light. Looks like I'm in the clear, I guess the filter was the culprit. Thank you everyone for all your help!

 

Good to hear it was simple. Ride on!

wrote:

Replaced the oil filter ...

Thanks for the update.

What brand was the suspect filter?

Good Ridin'
slmjim & Z1BEBE