I've got a YS 140 DZ that is not idling right. It runs fine above idle, but when you go to idle, the rpm's go up and down quite a bit (surging), and the engine eventually dies suddenly. I've tried a new glow plug (OS "F" type) with the same results. I've also tried adjusting the low speed regulator at least a full turn each way with no change.
My next step is to check all my fuel lines for holes/splits. Other than that, I'm at a loss.

Have any of you experienced a similar problem, or does anyone have any other ideas as to what my problem might be?

Thanks, Jim

What fuel are you using?

Magnum 30% nitro fuel, special blend for the YS 140 DZ. Similar to Omega 30% heli fuel.
The engine has been running great for 20-30 flights. It just started doing this all of a sudden.

Thanks, Jim

Jim,

surging is a lean condition. Dial the pump in to richen. You said that you tried it either way a turn but go in.....then maybe a little more. Another thing that may be the issue is an air leak somewhere. The DZ is less sensitive to these leaks compared to the other YS motors but it could be sucking air. Check the carb bolts, valve cover and backplate bolts for leakage....


Another thing to check is the rotor and make sure the pin (brass) is not loose. This can cause some grief. I have seen it a couple time....Don't just check the set screw...try pulling the pin out or see if the rotor is floating back and forth a little.

When re-installing the set screw rotate the pin off of the old mark. This way the set screw is grabbing fresh metal.

Another thing is most of the motors will have a double set screw....Tighten the first one up then run second screw down on top and it acts as a jam nut type of deal.

I would say I'd come up and work it out with you...but we are still not back in Colorado. No more Atlanta....been in Phoenix, AZ for about a week now. And the plan till about mid April.


Troy

Hey Troy,
Thanks for the suggestions.
I'll try them out and see what happens..

Jim

As a follow up I thought I'd let you guys know what the problem with this engine was, even though I'm a little embarrassed to say because I should have found this sooner.
It was very simple. Troy was right. One of the valve cover screws had fallen out and I guess it was sucking air in through the valve cover seal.
A new screw and it's running great again.

Thanks for the help, Jim

Jim,

Good news. How do you like the Colorado scene?

I'm currently in the Phx, AZ area. Been here since Jan1 and its been nice to be a snow bird type. Its starting to get hot now. high 90's yesterday was like 97-98.

Where re you flying? There is Loveaire which is a good field a little drive but good...Its over by Greely. Also a few miles south is the new LAMA field. There are some good guys there...but I have not been to the new site. The old site was excellent not sure about the new one.

I know that there used to be a club behind JAX army surplus in Fort Collins. But I think the houses have taken a bit of steam out of the group.


In any case glad to here your Dingo is working great!

TN

Hey Troy,
I'm really loving it here in Colorado. I've only been flying once since I've been here and that was at Love-Air. The move and getting reorganized really took up a lot of my time for a while. I sold a lot of planes before I moved and I'm putting together a new fleet of lighter planes for myself here in Colorado. I hope to be back flying soon, especially since the weather is really getting nice here now. Like you said, Love-Air is a nice field. It's about a 1/2 hour drive for me, but that's O.K. I've joined up there and will fly there more soon.
I visited the club behind Jax and it is fading out because the area is getting built-up around them. They have a new location further north, up around Wellington I think, but I have not visited there yet.
Does the LAMA field have a website? I haven't heard of them yet.

So are you coming back to Colorado mid April?

Jim