Just got back from the Field. It was a bit windy -- perfect for flopping waterfalls into the wind. I was coming down to the bottom of a waterfall ...(It was about my 10th consecutive full power for 5 seconds power off for about 5 seconds). thinking one more flip and I will fly out when she(YS110) quit as I went from idle to full throttle. I did not have enough room to get the speed up as high as I would have liked for my landing and pancaked it out cracking the bottom side of the cowl and bending the stock tail gear.

I walked up the the plane & the first thing I checked was my throttle servo--when I went to full I notice a lot of fuel running down the muffler. The fuel just kept on coming as if the system was releasing pressure - - like there was a leak in the system. When I went to grab my spinner to feel the motor it came off in my hand & then noticed that my prop (16 x 6 top flight super M-wood) had come lose. I pulled the plane back to the pits and pulled my vent line expecting that the system was already depressurized, but to my surprise it was not. I pulled the cowl to investigate and found nothing out of order so I mounted the prop and spinner to feel the motor and all seemed good. I ran it with the cowl off thinking I may have to richen up the regulator, but the motor ran so good again I did not see any reason to start messing with the needles.

Not sure what happened as this motor has never quit on me before(3 gallons of fuel) -- it appears that It must have went lean on the transition, but why? I may richen the transition up a bit as today it was spinning up to 10,200 and slowly pulling back to 9500 as it moved on to the high speed. Also, it is a mystery to me why so much fuel came running out when I opened the throttle after landing? As if I was too rich not lean?

Please if you have any insight for me?

Sounds like the plunger may have become stuck. Could have been a piece of crap that blew through. Do you have filters on both lines? It's important to have one between the engine and the check valve as well as one on the incoming fuel line.

Try going to www.ysperformance.com and going through the setup instructions. It will help you get the regulator set correctly.

Good Luck!

Yes I do have filters on both lines. I will clean them out.

According to the setup instructions the regulator is set up correctly at the factory setting...have not needed to touch it.

OK if I understand this correctly...what most likely happened is the plunger got stuck open causing the motor to flood and back fire when I went to full throttle.

Dave, I really do appreciate the support & answering questions even on a weekend...a holiday weekend!!! That is stellar support. It is your support that gave me the confidence to try a YS and it has made my hobby all that more enjoyable. Thank you!!!!

If the regulator sticks, it's nearly always in the open position. When you throttle back the regulator spring pushes the plunger down harder on the seat, letting less fuel in. My hunch is that your reg is set a bit too rich. Try going in 1/4 to 1/2 turn and see what happens. YS engines do not like to be overly rich on any of the settings except idle.

I disagree with not adjusting the regulator. The factory setting is just a starting point, and sometimes it's right. It will vary with type of fuel and variations in weather. Don't be afraid to adjust it, that's why it has a screwdriver slot.

They usually stay set once they are adjusted, unless there's a big change in fuel or temperature.

Thanks for the advise. I have not moved the regulator because it seems good....

1) Plenty of smoke on transition, but no bogging. Seems plenty rich because of the smoke and seems plenty lean because transition is so fast that It can hardly be detected.

2) My initial RPM is very high. Was over 10,000 with the 16 x 6 wood! It is typically 9,900 or so with a 16x6 APC. Then it takes a few seconds for it to bog back to the high speed needle, wich I usually set at about 9,500 or so on the ground because I am thinking it will lean out a bit in the air.

Do you have any more spicific instructions that will help me determine the correct setting of the regulator?
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The instructions I found don't really say how to set it or am I missing something?.....

1. Be sure that the engines has fuel lines connected per the instruction sheet supplied with the engine.

2. Open high-speed needle valve 2 turns.

3. With fuel tank filled completely and the fuel lines connect properly, prime the engine by running it at full throttle with the starter for 5 - 10 seconds. DO NOT CONNECT THE STARTING BATTERY WHILE DOING THIS.

4. Set throttle at 1/4 open. Have a helper hold the airplane if so mounted.

5. Connect starting battery and apply starter. Engine should start immediately. If it does not, check for fuel delivery and make sure the glow plug is operating properly.

6. Upon starting, allow the engine to run at 1/4 throttle for at least 30 seconds.

7. Advance throttle to full and adjust the high-speed needle to a slightly rich full power setting. When set, slowly reduce throttle to a fast idle.

8. Allow the fast idle to continue for a few seconds, then advance the throttle to full. If the transition from low to high is rich, the regulator screw should be turned clockwise. If the transition is lean, turn the screw counter-clockwise to richen. Adjustment should be made 1/4 turn at a time until you are very close then 1/8 turn for fine adjustment. DO THIS ADJUSTMENT WITH THE ENGINE STOPPED FOR SAFETY.

9. When the transition is set correctly, then reduce the throttle to full idle. If the idle speed slowly rises, screw the idle screw clockwise to richen. If the idle speed slowly drops, open the idle screw to lean. Work 1/8 turn at a time with the idle screw adjustment. Correct idle speed is 2200 to 2400 RPM. At this point the engine should be set correctly. FURTHER ADJUSTMENTS WILL BE REQUIRED AS THE ENGINE BREAKS IN.


Again thank you very much for the help.

I really can't explain it any better than I did on the site. It tells you exactly how we set them here. I also have a hunch that your HIGH SPEED needle is set too rich. YS engines do not like a super rich top setting. The engine will not lean out in the air. That is the beauty of the YS fuel system. A couple clicks back from the top rpm setting is rich enough.

Am I missing something on the sight? All I found was #8 above in bold...

8. Allow the fast idle to continue for a few seconds, then advance the throttle to full. If the transition from low to high is rich, the regulator screw should be turned clockwise. If the transition is lean, turn the screw counter-clockwise to richen. Adjustment should be made 1/4 turn at a time until you are very close then 1/8 turn for fine adjustment. DO THIS ADJUSTMENT WITH THE ENGINE STOPPED FOR SAFETY.

I cannot find more of a description -- am I missing something?

I was afraid that I was setting it too rich but...

1) The only time I have much of a smoke trail in the air (yes on 30% heli) is at lower throttle settings. BTW, I did not notice an increase in smoke when I went from YS 20/20 to CP 30%.

2) The motor seems to be pulling the 16 x6 more toward the top of max rpms. I have leaned out the high speed enough to see it transition to 9,900 and pull back to 9,780 with a 16 x 6 apc on the high but as I went leaner I did not gain any RPM so figured I was maxed.

Thanks for your help Dave

There are 9 steps in the adjustment instructions. If it still shows only #8 when you go to the site, hit your refresh button. I just went there and all is fine.

You are running an OS Type F aren't you?

What I was looking for were more specific instructions for adjusting the regulator. For instance what to look for that would tell you the motor is rich or lean on transition.

It is #8 on your list.

8. Allow the fast idle to continue for a few seconds, then advance the throttle to full. If the transition from low to high is rich, the regulator screw should be turned clockwise. If the transition is lean, turn the screw counter-clockwise to richen. Adjustment should be made 1/4 turn at a time until you are very close then 1/8 turn for fine adjustment. DO THIS ADJUSTMENT WITH THE ENGINE STOPPED FOR SAFETY.

One more thing, how fast should I be comfortable spinning the YS110? I am thinking I might have to jump up to a larger prop or drop back to YS 20/20 fuel. --maybe it is not an issue with the style of flying I do because I am rarely at full throttle for extended periods of time.

At what RPM would you expect the valves to float?

Thanks Dave

You have to be the judge as to whether the transition is lean or rich, I can't teach it.

Not over 10000 static, ideally 9000 to 9500.

Valve float at probably 12 to 13000 depending on how good the springs are. Don't know, no reason to run one at that rpm.

Thanks for your help. I am running the F plug.

If I could be in 2 places at once I would see you at the show.

Tough to do.

Good Flying!