Mailing List Message #67397
From: William Jepson <>
Subject: Re: [FlyRotary] Re: Premix vs OMP
Date: Sun, 26 Feb 2023 09:53:50 -0800
To: Rotary motors in aircraft <>
Richard and Mark, 
One other solution is to run a 2 stroke oil tank and “short circuiting” the plumbing. Richard didn’t you have a separate tank system for 2 stroke oil? All of the later model 2 stroke motorcycles came with this system. The last Kawasaki 2 stroke H2, (the 750cc triple) had a involved system that injected oil into the carburator float bowls and also fed the main bearings. Still in the combustion path on a 2 stroke. The rotary would be much simpler with only the feed to the rotor housings needed.

On Sun, Feb 26, 2023 at 9:24 AM RICHARD E SOHN <> wrote:
The difference between premix and OMP is the two stroke oil you would use in premix. The OMP is using motor oil with all the disadvantages it has when it gets into the combustion chamber. Also, you can not use synsetic oil in the engine when using the OMP. 
There is a lot more info available in rotary engine related discussions on the internet.

From: "Mark McClure" <>
To: "Rotary motors in aircraft" <>
Sent: Sunday, February 26, 2023 8:01:41 AM
Subject: [FlyRotary] Premix vs OMP

I now have 2 engine cores. One is set up for premix and one is set up for OMP.  (I of course just purchased a set of SS braided OMP lines before acquiring this 2nd engine)

My search of the listserv (2006-2010 results) shows that overall premix yields a better distribution (at least for the RX-7 engines with 2 OMP lines). 

Is the general consensus still that premix is a better distribution? Still recommending .7oz to 1 US Gal?


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