I have problems with my new engine, YS 63FZ. It sometimes runs nice, and sometimes very erratic. I start it, the highspeed needle set to a few rpm below the max. Up in the air, at full throttle it runs very nice. It runs nice as long as i don`t work with the throttle. Take it down to half throttle and up again it starts to run erratic. Then i let it fly at idle for a few seconds and up at max again, it runs nice again. When i make lots of rolls it starts to fail again. The pressure in the tank is fine, as i disconnect the fuel line on the oneway vent i can hear that the pressure comming out. I have tried a new tank, same problem. Could it be the diaphragm that causes the problem?. I have run the engine for about 5 hours, so the runin should be done. I have checked the tapet clearance. The fuel is 5% nitro and 18% aerosave. I can not see that the low nitro causes it, because at times it runs very nice. Anyone out there that has a tips about what is causing the problem?

Bjarte
Norway

I have one and it is a sweet engine. It does like to be run on YS 20/20 fuel. The low nitro fuel makes the needles very sensitive to adjustments. Is it running rich in the mid range or is it going lean?? If it is rich try turning the regulator in about an 1/16 to 1/8 of a turn and see what that does to the engine.

Dru.

Seems like the damper in the carb passes the center and starts to close again a little bit at full throttle, if let it go as far as it can mechanical. When i run it on the ground, and go from idle to full throttle, it starts to richen after a few seconds. From full to idle it settles down to a nice idle. And from idle to full it goes right up with no problems. It is the erratic run that it gets in periodes that confuces me.

Bjarte

Based on what I read (and experienced 1 time), I think your problems will clear up with higher nitro. I keep hearing that ys loves 20% and higher nitro. I use 30% heli fuel. I do know one guy at my field who had erratic running problems with his ys (15% nitro). I gave him 1/2 gallon of my 30% and problems disappeared the first tank. He then tried using 15% again, problems returned. Now he only uses ys 20/20 fuel.

Guys at my field don't like ys engines. They say they are hard to tune. I believe it was because they never tried upping the nitro.

Do a search for ys in the glow engines forum. You will find a lot of info regarding ys and fuel.

I agree with the nitro content. This engine was designed to run high nitro. I started wuth 15% and the needles never did settle into a good run. After I filled the tank with YS 20/20 fuel I did not look back. It had more power, better idle and no sag in the mid range.

Dru.

It is the fuel. I use 30% heli fuel and the YS 63 loves it!
Use at least 20% nitro and a low viscosity oil.

Jim