Hi Troy -- greetings.

I have a YS110 with about 7-8 gallons through it or so. I have been experiencing something strange with it recently. It now idles really well and will transition very well on the ground and for the first couple of flights. Then on the third flight, the motor will not transition well at all, sometimes refusing to go above the mid-range, even with wide open throttle. This has happened about 3 times over the last gallon of fuel or so. I thought maybe it was overheating, but it does not feel scalding hot on the ground and the first couple of flights are fine. The engine has plenty of smoke on it during flight and especially when increasing the throttle. Temps over here are about 60 degrees or so when I'm flying. Any thoughts?

Are you flying flights back to back to back. Or do you let the engine cool in between flights? This is important in HOT temps.

60deg F is what I'm assuming 60deg C would be really hot. At these lower temps I would bet you are a little rich on the top end. If the transition and idle are excellent then I would try leaning the top end just a little and see if that is the solution.

Another option could be a partially clogged fuel filter. Or some dirt or debris could be in the regulator. When the engine sits the dirt gets stuck to the side of a passage and then after its run a bit the dirt or debris gets loose and partially blocks a passage.

I would try to lean it out a little and see if it goes away. Be careful you don't want it to start detonation or backfiring. It is more likely a borderline too rich condition, but its tough to diagnose any problems like this over the Internet. If I heard the engine I could tell you but alas I'm not in Cyprus.

Another thing is you have a few flights on it. Is it the original Glow plug? I end up changing plugs about 6-8gallons usually. This may be an issue but if it runs fine for a couple flights then acts up, then the next day out its fine again probably not the plug but it could be.


Troy Newman
Team YS Performance

Thanks, Troy -- I have been cautious about leaning the top end ever since it backfired one time and tore my aluminum spinner in half -- I will try leaning it a bit though. I have changed plugs about 1 month ago so I think thats fine. I also let the engine cool down between flights. I will also check the fuel filters and look into the regulator. Thanks again.

Somes its just about 2 clicks on the HS needle that can have the affect.

Also of note, sometimes a glow plug could cause this even if it only has 10 flights on it.

Troy

In December I flew my 110Fz and after the day was over I put after run oil in the engine ( the correct one from performance specialties). On the next outing a couple of weeks later the engine would not start and was not getting any fuel. I took apart the reg. and noticed that I had put to much ARO in because everything was gummed up. After flushing it out, the engine ran fine for the rest of the day although it was a little hard to start. At the end of the day I drained the tank and ran the engine dry and did not use ARO. Now approx. 3 months later the same starting problem happened. When this happens I noticed that when I relived the pressure from the tank there was very little. After many tries she fired up on her own and except for one other accurance she was fine for the rest of the day.

You might run some fuel through your check valve. The oil can gum up it a little. Pumping fuel through it will help clean it out. Also you can pump fuel to both sides of the regulator and it will help this situation as well.

Another trick

with No glow attached. Open the main needle 2 turns more than its set running position( this means you would be like 3.5 to 4 turns open). Open the throttle to full power. Again NO GLOW attached. turn the engine over for a 10-20 secs with an electric starter. You will hear it when the RPMs change and it gets "wet"

Now close your HS needle back down to the running position close the throttle to idle. Apply glow and start.

Works 95% of the time.

Troy Newman
Team YS Performance