RE: YS 170 DZ CDI
My new "revised" pump has the two diaphrams and seems to work well.
With regard to oil content and the cdi, IMHO YS needed to go low oil for a reason and it had nothing to do with smoke trail.
Simply stated (in my case) the less oil the better. My DZ170cdi on 20% oil in my Aries will oil up the plug unless it's set super lean (top and bottom) or you spend the whole flight doing outside loops, even 15% oil is/was a bit marginal if I wanted to spend a couple of minutes just cruising around upright instead of flying the schedule. On the ground an oil fouled plug might clear itself if you're really lucky.
10% oil seems to be the ticket for me now with a prop that will let me turn about 7.5K+ rpm.
I'd bet my Aries that everyone has their own thing that works for their particular engine. I also learned two very important things (among many) from my experience starting out with a brand new YS engine, (1) NEVER buy a second hand one and (2) if it's been running great for ages and then you have to start touching the needle or reg, it's getting close to rebuild time and needle fiddling is only going to delay it.
Cheers