I have a 2021 800 trail. 146 hours, 1100 mi. It's been flawless up till now. Of course it's out of warranty. My last ride out the oil light started flashing at idle. I got it back to camp brought it home put a gauge on it and I have 5 PSI at idle, and 25 PSI at 4000 RPM. Assuming it was either a stuck pressure relief valve or what I really guessed it was bad Main or rod bearings on the crankshaft. So I pulled the engine out took it completely apart and I can't find anything wrong. There was some flaky material on the oil pump pickup screen, pieces may be a 1/8-in wide and 3/8 in long a couple of them that were maybe .003" in thickness. I've already ordered and received a new oil pump new pressure relief valve and bearings just because. But I really don't want to put this thing back together and fire it up and have the same issue again. I have blown out the oil cooler lines with high pressure air and it does seem some what restrictive to me. I've torn the engine completely down from one end to the other and the shavings I found I cannot find where they came from. Like I said I'm really having an issue putting it all back together and back in the buggy to find out I didn't change anything. Anybody got any insight

[2015 Z Force 800 53/Trail EPS]

A lot of the smaller stuff is common but the larger stuff may not be. Some of it looks to be rubber off cam chain tensioners and may be extra casting materials. Also as they has a shared sump prior to 2022, some of it may be from the transmission. You said the oil cooler seemed restrictive...this reminds me of another member that also had a low oil pressure problem and found that his oil cooler was almost completely plugged with trash from manufacturing. He got that fixed and fixed his problem. I would inspect, then plasti-gauge one of the rod bearings to confirm that are OK then if so, replace the oil pump and relieve parts (as well as the rest) and as there are better oil coolers out there, replace it with a better one before re-assembly.

The clearance on the rod in main bearings is .0015", so That's not the problem obviously. I will give the oil cooler a shot remove it and see what I can find there. Thank you for your help

It's fixed! Although I put a new oil pump and oil pressure relief valve inside also changed the main and rod bearings none of those things appeared to have anything wrong with them. I fully believe it was the oil cooler being partially plugged. It now runs at 35 PSI at idle when it's warm, and 70 PSI at 5500 RPM. I am very happy with the results but that was a lot of work.

[2015 Z Force 800 53/Trail EPS]

Great news. So sounds like your advice to everyone with this issue is to first, look to the cooler, the relief valve and the pump first before full engine disassembly. This is at least the second time the oil cooler had been the issue that I have heard of. I suspect one could rig a bypass line to test it while having a pressure gauge on it to see. 

Great detective work and good outcome, just too bad it took so much work.

It's fixed! Although I put a new oil pump and oil pressure relief valve inside also changed the main and rod bearings none of those things appeared to have anything wrong with them. I fully believe it was the oil cooler being partially plugged. It now runs at 35 PSI at idle when it's warm, and 70 PSI at 5500 RPM. I am very happy with the results but that was a lot of work.

Wow great info.  what is the process for flushing the oil cooler or is it just a swap out with a new one?  What would give us any indication a new CFMOTO cooler would not have factory casting trash or other issues plugging it? 

I'm thinking I will run some sea foam in my oil, get it nice and warm, and let it sit in there.  I Live in Wisconsin and we have very few winter UTV trails so it will be tough to get many miles on until spring but I think as long as I get it warmed up and pumping good the treatment should flush through the oil cooler and get through the oiling system.  it can sit in there until at least spring and then I do an oil change to start the season.

[2015 Z Force 800 53/Trail EPS]

Not sure I would do that. Anything it breaks loose in the cooler..or anywhere after the filter.. will be pumped straight to the rod bearings first..I believe..not the filter. Then...that's it.