How to increase oil pressure?

Your engine is a little older than the ones that had crankcase fretting and a hot engine is harder to turn by hand than a cold one.

After the engine is warm and you advance the throttle and then bring it back does the oil pressure get lower when you advance the throttle and then go back up again when you return to idle? This type of low oil pressure could be caused by a poor ground wire. You may have a ground, but a poor one. To test it pop the panel out and use a wire with an alligator clip on it and hook one end to a known good ground and the other to your guage. The other thing that causes it to fluctuate is a sensor starting to go bad. If it's an original oil pressure sender I would definitely replace it. I would replace the oil pressure sender if it sin't a poor ground. This is the #1 cause of pressure issues for the average person. Don't look for exoctic issues because it usually a simple common cause and fix.

The next easy step to take iwould be to put a new oil pressure regulator spring in and get rid of the ballbearing and put the newer style mushroom pressure regulator in especially if these are originals. Just takes a few minutes to do this. It's the plug that should be safety wired under the oil filter on the bottom of the pump.

The oil pressure can be raised, but I highly advise against using a shim until everything has been ruled out. You almost never need to take this step and many who have failed to do COMPLETE diagnostics do raise the pressure and then unbeknownst to them it's actually above max because they never found the original problem and tried to put a bandaid on it.

Roger,

thanks!

As to your first question: no the oilpressure is 2.0-2.5 at 5000 rpm and a bit less at lower rpms.

Thanks for the tip with changing the spring etc. Is there a Rotax part-# for the "mushroom" type valve? then I will try that first and only add the shim if it's still not better.

I also will do the complete 5 year rubber replacement, which after 15 years is more than overdue, in in the course of this will look at the oil pump as well.

I also have never taken the carbs apart, all I did is renew the rubber flansh several years ago and balanced them every 200hrs or so. I now have 750hrs on the engine and am a bit hesitant to take the carbs apart, they run just fine now....

Again thanks

Joe

GOOD advise roger . On my 912 ULS wIth similarité problem, new spring and mushroom plug fix the problem

https://www.cps-parts.com/catalog/rtxpages/912914oilpump2.php 

You want #41 mushroom and #3 spring.

I would replace my oil pressure sender if it's fairly old.

Excellent advice by Roger Lee.

His advice also fixed my low oil pressure problem (2006 - 912 ULS).

Thank you again, Roger!