Is anyone out there using onboard glow on their YS? I have a 140 sport that has 1 gallon through it. I know it's still breaking in. At first it was mounted upright on a break in table, and it was spitting fuel badly. But it was rich and that's what I wanted. As the gallon got used up, I slowly adjusted the regulator in until the dripping pretty much stopped, and the transition is good. But I still think it's a bit rich on the regulator because when I put it at about 4000, it will get rich and lose RPM's. But the regulator is only about 1/2 to 3/4 turns OUT from dead bottom. I'm afraid to lean it anymore.
The idle isn't very consistent. I can get it down to around 2000, and sometimes it will idle pretty much forever without loading up. However, twice on final (since mounting and flying) it has died on me. Once I restart it, it runs great and idles fine. But I don't feel like it's a very reliable idle right now. I was wondering if onboard glow would make the idle more reliable, or is it a break-in tuning issue?
For what it's worth, the engine is mounted on it's side in a 10.2 lb ultimate. After flying, the engine is hot, but not scalding hot. I always touch the head after landing to make sure it isn't getting too hot, and it's not.
Maybe the regulator needs to be cleaned???

I have never seen a YS that needed an onboard glow to sustain a good idle, and your 140 shouldn't need one either. Do you use a filter on the fuel line? If no, you should. Does the idle improve if you leave the glow starter on? If yes, it is too rich. Remember, the regulator has very little effect on the engine at 2000 rpm. I would start by cleaning the regulator out. Your symptoms COULD be caused by debris in the regulator, considering how far you have the screw turned down.
Paul

2slow2matter:

There is a known issue with some of the 140 sport engines. I think you should check yours, because it sounds like it might be at the heart of some of your problems.

I have one that I could not get the low end to lean out enough to idle smoothly. After hours of adjusting and re-adjusting, I finally got it to run OK on the high end, pretty good in the mid-range, but it would only idle down to around 3000 RPMs. If I tried to get it to idle any lower, it would run rough, spit fuel, and eventually die. I had the air bleed screw out so far it was about ready to fall out of the carb completely, but it was still too rich. Leaving the glow ignitor attached helped, but didn't completely solve the problem. I finally gave up and called YS, and spoke to one of their chief technicians about it. He listened to my description and quickly told me that some of the 140 sports were made with the wrong size hole in the barrel of the carburator. This hole is the one through which the engine draws air while idling, the one that is blocked/unblocked by the idle screw. He told me to take the barrel out of the carb and drill the hole out to 1/8" inch. (It's the only hole in the barrel) I did and my problem was solved. You might want to check yours and see if it's undersized, as it will cause you to chase your mixture settings all over creation.

If you have to drill the hole out, make sure you don't allow any burrs to remain when you re-assemble it. Reset your regulator screw to flush with the housing, and start the motor. Adjust the high end first, lean it until you see or hear maximum RPMs, and then richen it until the RPMs drop three or four hundred. Now throttle back to around 4000 RPMs and adjust the regulator for best running. You should need only small adjustments here, like 1/8th of a turn or less. Once you have the mid range adjusted, go back and re-adjust the high end. Do this until you can't improve either one any more at all before you mess with the idle. By the way, the high speed screw is a regular needle valve, so CW leans and CCW richens.

Now throttle down to as low as it will run and keep running, and begin adjusting the low speed air bleed screw. Remember, it's bass-ackwards, opposite from the HS needle valve, so CW richens and CCW leans it. Leave the glow ignitor on in case it's rich, until you get it close to correct. Lean the low end for smooth idle, let it idle a few seconds and check the transition. If it cuts out suddenly, it's probably a fuzz lean, if it coughs and sputters and then goes it's probably a little rich. You should be able to get the idle to around 2000-2500 without any problem, and without the need for an on-board glow ignitor. Mine will idle at around 1500 if I want it to, and will idle all day and then spool up immediately when I say "giddyup".

You might want to call YS and talk with them yourself about this problem, after all, I'm just a "voice" on the 'net, but if you'll do a search I think you'll find some previous threads on this problem. I hope you get it worked out, and I hope this helps.

David

Dave,
That helps tramendously. That sounds like my problem exactly. I'll take the barrel out and see if it's 1/8 or not. I can lean lean lean and it still idles rough and never speeds up like it should. And, like you, I felt like the air bleed screw was about to fall out.
Of course I use a filter, and to me this has been a problem since I first started it, and it was brand new.
Thanks again...

Great!

By the way, I meant to say something in the first post about this, but I forgot. YS engines are known to run hot. That's just their nature, and also a function of the higher nitro percentage. But yours has probably been running lean because you've had the regulator turned way in trying to get it to idle right. Once you get the situation sorted out, I think you'll find it runs a lot cooler. Once I got mine fixed and set right, it started putting out a stream of smoke that almost looks like the plane has a smoke sytem in it. I've thought about trying to lean it up a bit to save fuel, but it's running so good I'm afraid to touch it. Once you get these YS motors right, nothing runs better or has more power.

Funny thing is, the motor cutting out on final is why I came to own this plane and this engine. Another member of my club had bought the plane and motor together, and on the second flight was turning on final when the engine quit. It was too far down wind for him to hear it, and there were other planes in the air, too, so he didn't realize it. He continued his turn and stalled the plane, and it crashed before he could save it. He thought he had simply pulled his throttle stick back when his throttle trim was all the way down (JR radio), and assumed it was his fault. He bought another plane, installed the engine, and then discovered it wouldn't idle. He sold it to a second club member, who messed with it for two or three months with no luck, who then he sold it to me. (I got a steal of a deal!) I have quite a bit of experience with small engines and glow engines, so I figured I could fix it in no time. After I had pulled all my hair out, I called YS. Now I have a sweet running YS 140 sport on a sweet flying 72" QQ Yak-54. Life is good!

David

Well, I'm definitely going to look into that. I'll get back with you on this post when I do.
I got this engine, NIB, at a swap meet for 200 bucks, and it came with a central hobbies pattern header. I use the header with no muffler, and it looks good and sounds even better on my seagull ultimate....
On the top end, it has lots of smoke. I can see the smoke from a long ways away. Mid throttle also has plenty of smoke, but the low end not so much, but it still idle's rough. Like you, I've chased the needle all over the place.
Well, instead of typing, I'm going to go get it out right now and look into it.
Thanks again...

David,
Problem solved.
I took the carb barrel out, and the air bleed hole was definitely smaller than 1/8 inch. So I drilled it out. While I was at it, I cleaned the regulator, but I didnt' really see anything in it, so I don't think that did anything. But while I had the carb barrel out, I noticed that the bottom O ring on the intake manifold had been pushed down and out of its seat, and was 1/2 hanging in the carb. So I took the engine off, took the carb back plate off, slid out the intake, fixed the O ring, and put it back together.
All of this, and I was able to richen the regulator back to flush, and it will idle all day at 2100 to 2400. And I'm getting good smoke all the way through the range. And, the top RPM's on my 16X10 APC went from 8400 to 8700 like that, and it's still a bit rich....Probably turning 9 in the air....perfect.....
All of this and no onboard glow! Today I ran two tanks (48 oz) through it, and it never once died unless I killed it with the trim slide. I was able to idle down on final without worrying about if it was going to die or not. I did countless touch and goes with no problems.
This engine is a horse!!!
Now, if my Bridi Killer Bee maiden in the morning goes this well then I'll be VERY happy!!!
thanks again!!!
Carl

Good Job! Sounds like your motor had more problems than a run-over cat.

Good luck on that maiden flight, too.

David