I'm currently having some growing pains with a DZ 140. I have been running other YS engines for years with great results but this one has me a bit stumped. Being that it does not pressurize the fuel tank it is a bit different then other YS engines or any other glow engine I have ever run.

So here is what is going on. Fuel is Wildcat 20/20 all synthetic, plug is OS F and prop is Engle CF 16x10 three blade. I do have the YS filter clunk in the tank and a filter prior to the pump.

Top end is great, I have the engine mounted on a Circus Hobbies Reed Falcon that weighs 9 lbs. I have not put a tach on it but running slightly rich it sounds in the ballpark of 8,000 to 8,500. The issue is that the mid range is lean. We all know what the YS lean transition sounds like. On my 115 WS I richen up the high speed needle and the detonation goes away, no big deal. With the 140 in order to do this the high speed needle has to be so far open that there is no power increase between 1/2 and full throttle. Obviously it goes through fuel really fast this way and that was cause of my first dead stick today. So I went back to peaking out the high end but still rich from peak and the poor transition is back. Next option was to richen up the low end. I adjusted the pump regulator in until the transition was flawless. The engine now runs flawless except.............the idle IMO is way too rich. When I remove the glow driver I have to have the idle rpm rather high and then the rpm drops much more then what I am comfortable with. Although the last flight today was Flown this way and until a fuel line came off the regulator it ran great. Dead stick # 2 and a scuffed wing tip....ugggggg.

The fuel line that popped off is the one that runs from the regulator to the carb and it did have a fuel line clamp on it. Anyone else have this issue? The next thing I plan to try is upping the nitro to 30% to help my confidence with the idle rpm drop without glow. Any other ideas?

Thanks in advance.

Make sure you run heli fuel. The high vis oil makes a difference in your settings and could be the problem.

You may be on to something. The one thing I wanted to try today was a bit more nitro. I took the half gallon of Wildcat 20/20 that I had and mixed in a half gallon of 40% home brew that contains 20% Cool Power synthetic. On the advise of Richard Verano over the phone today I changed the plug. I also leaned the diaphragm screw just enough to keep the transition detonation free. Today I had 3 flights where the engine ran well. Not spectacular but well. I will have to check into the viscosity of the Power Master oil as my plan was to have my buddy that mixes fuel to make up a few gallons of 30/20. I'm hopeful that these changes and a bit more run time will get the engine to settle down a bit more. Thanks for the oil tip, I will follow up on that.

Shawn
The 30% sounds like a good idea, as these engines seem to like their nitro. I have a bunch of 30% nitro, 21%syn that I mixed for heli use. If you want a gallon to try pm me and you can have one.

Scott, that would be great, I should come up and fly with you and your group for a day. I didn't know you flew Helis as well. I'm just getting back into them as well. Currently building an old Heim 222, remember those?

Me - Fly Helis!!! God no. I have enough problems keeping an airplane in one piece. One of my best friends, who passed very suddenly and unexpectedly, flew helis. I mixed all of his fuel since YS120's have a habit of being thirsty. I have some 30% and I have ingredients to make whatever I need. Come up and make some noise. Jeff was supposed to bring a hot rod up here sometime too.

Scott