flyslow

Hi there I'm having problems getting a smooth transition with my new YS50. The engine has had about 20 flights now. The muffler I'm using is the Funtech 3D. The problem is in the transition from idle to greater than half throttle and the reverse, and also using throttle hold for autorotations. The low speed needle valve is currently set at 1 3/4 turns out and the main needle is about 1 3/8 turns. If I lean out the main needle valve any further i get engine flame outs when reducing throttle on approach to land. It seems like the engine isn't getting enough fuel at the low end and has a lean cut out. In addition when advancing the throttle from idle, at first there is very little smoke then at about 1/4 throttle there is a significant increase in the amount of smoke. There is not a linear increase in smoke. When using throttle hold when conducting autorotations, the throttle hangs for about 1-2 secs before reducing to idle, there is not an immediate cut to idle - this usually indicates a lean situation. If you let it idle for about 20 secs the when advancing the throttle it hesitates quite badly but to me it sounds like a rich situation. I have tried fuels with various amounts of nitro but its the same on all fuels. I am already 3/4 of a turn greater than the reccommended for the low speed needle so i am hesitant to go any further. I have also tried a different check valve but once again no improvement. My thoughts are leading towards a problem with the carburettor? Any suggestions would be greatly appreciated

petec

My Feedback: (58)

I fly YS engines in my planes so I pulled the OS out of my Raven and put the YS 50 in as soon as I could get one. I can tell you this much as I am still breaking mine in, this thing is a monster.

I had the same issue you did, it would hang or flameout on transition. After chasing my needles all over the place I arrived at this. My low speed needle is at 1 1/8 turns out and the high speed needle is at 1 1/4 turns out. The YS engines I have tuned always were slobbering rich at the recommended needle HS needle setting and this one is no different. It is just easier to tune an airplane engine since you can make changes while it is running

I am running the same Powermaster YS 20/20 mix I use in my 4 stroke YS engine with no issue, an OS #8 plug and a Youngblood MP2 pipe.

I gave a friend of mine my old OS 50 for his Raven and he was there when I first fired up my YS. To say the least he was impressed and so was I. The head speed is up a noticable amount and I will have to modify my thottle and pitch curves.

Just be aware that these needles are EXTREMELY SENSITIVE so make minor adjustments.

Troy Newman

I don't have a huge experience with the heli engines. However what you are describing is a slightly lean condition on the low end.

Also think glow plug too. The engine is new and its breaking in...at this point in their life...small little bits of metal are grinding away inside the engine and it breaks in. This are microscopic pieces that are being clearanced as the rings, bearings, and other parts seat themselves.

If these little bits get on the glow plug coil nit will burn a hot spot in it and burn the platting off the plug coil. The glow plug can still glow....but it won't be as effective...You need to change the plug when this happens. Its a common thing with all glow engines that are breaking in.

This problem is very noticeable in the 4 stroke engines as they use the type #F plug of the YS plug. This is a hot plug...The #8 that you would use in the heli engine is a colder plug and would be less susceptible to this problem but it could be the easy solution.

After about 15-20 flights the engine will be broken in and this will be much less of an issue and the glow plug will last much longer periods of time.

Troy Newman
Team YS

flyslow

Thanks for the replies,
I'm still not convinced its just a tuning issue, I had 1 flight the other day and the engine was lean right from the start when no settings had been changed from the previous days flying. I'm heading back out to the field tomorrow and I think I'll start with the factory settings again (and a new glow plug), but this will be the fourth attemp at tuning from the factory settings by 2 experienced heli people with no luck. Beyond this I'll be looking for something physically wrong with the engine etc.

One thing that was bought to my attention is that Funtech is now making a a pipe for YS50 its model is A395 HN-50 Type TE-3D, the current pipe that i am running is the A170 HN-50 Type R-3D. Has anyone had any experience with this pipe / engine combination?

Flyslow

Troy Newman

The engine can act lean when it first starts up. This is because pressure has not built up in the tank. You need to get the engines to warm up slowly. On the airplane engines I tend to run them at about 1/3 power for 30-40secs and then take them up to full power...If it starts to act lean I back it down and slowly come up again.

When the engine is cold and the pressure in the tank is not up spec there is not enough fuel flowing through the regulator when you are at high power settings. This is becasue the regualtor and needle valve are adjusted for the engine under operating temps and pressure in the tank.

So to help the situation. Fill the tank with fuel, close off the pressure line with the check valve and add a little extra pressure with your fuel pump. This will give the tank a little head pressure to start off. It will help it get up to pressure quicker.


Troy Newman
Team YS

flyslow

Troy,
I think you misunderstood what I was saying. Flying the heli the previous day and the tuning for the top end was ok. The next day of flying it was lean on the top end without changing any of the settings, not that the engine was lean on start up. Today the heli was richened and the glow pulg replaced, but it had no power and headspeed was down. I find it hard to believe that this is just a tuning issue, two of us have been working on this heli for the last 12 flights with no avail. It has been a most dissappointing experience so far.
Flyslow

Troy Newman

If the engine is running inconsistent like this and its not a tuning issue it could be other things like fuel, or at worst case something internally wrong with the engine.

It may need to be sent to YS for service. I know you are in Australia you need to deal with the importer down there.

Troy Newman
Team YS

archiebald

Don't know if your problems are fixed, and sorry for the long story but here goes.....

I bought a YS50ST back in early summer to replace my venerable TT46Pro. (BTW, I am not a tuning expert, just reporting what I found)

I couldn't get the Hatori 522 pipe I wanted for it at first so I ran it on my old Funtech HN50 that was far too restrictive on back pressure (causing spit back and no power), but the engine ran sweet while I was breaking it in on my standard 23% nitro and OS#8.

When the Hatori arrived, I was excited but severely let down by the engine cutting out in the mid-range, just as described above. After I finally managed to get it off the ground, I had several flame-outs and a couple of bad autos resulting in crash damage. I put new fuel and clunk lines on everything, cleaned everything and I had even tried a YS#2 plug but nothing would really get it transitioning right.

It was so bad, I put my old TT back in the heli just so I could get some flight time. By this time, I had probably about 25~30 tanks through the YS.

I then decided to give it one more chance before sending it back to the factory. I stripped and cleaned the carb and regulator (found nothing), cleaned the check valve (nothing) and re-assembled. However, things were definitely better and during testing of needles, fuel and plugs, the best settings I have found so far are;

30% nitro, Enya #3, low needle 1/2~5/8 turn out, high needle 1 3/4 turn out. (It still doesn't like the OS#8)

Actually, I think I am still too rich on the high needle, because the crank case doesn't even get hot to the touch after flying FFF for a minute or two so I will be trying another couple of clicks in this weekend.

I know the low needle setting looks too lean, and it does hang a little when returning to idle, but believe me, overall it runs best at this setting. I tried all settings on the needles before and if the low needle is too far out, the transition problem just gets worse and worse. There is no way mine will transition at all if I were to set the idle needle to 1 3/4 as described in the OP.

Also, I played with my throttle curve in Normal and I have found best results at 0 - 38 - 40 - 55 - 80. The important point is step 2 at 38%. If I set it back to 20~25% it seems to be worse. My Normal pitch curve is low -5deg, mid 0deg and high 10.5deg (Idle 1 and 2 are straight -10.5, 0, +10.5). I think this relationship between throttle and pitch in Normal helps the engine to get on song before the rotors start going positive pitch.

The only difference between the earlier testing and now is the air temp. In summer it was 30+degC, now it is around 12~15degC. I guess this has helped me somewhat so I await next summer with interest (by the way, my altitude is 700 meters ASL)

With these needle settings, it is necessary to raise the idle trim several clicks to start her up, and then bring it down to normal after starting. But, otherwise, no problems.

Now, I know I can at least trust the engine so I am making a bit of progress on fine tuning.

The biggest test I give this engine is to land, let it idle about 10 to 15 seconds and then bang the throttle up to full. Right now, it is picking up instantly, but like I said, with the idle needle out any more, it will just bog and die in transition.

Even with these settings now basically working, I still have to nurse her through the transition on the first take-off, but after that, pick-up is nearly perfect. I am assuming that this is because the tank has not got up to full pressure on the first lift-off.

And just to re-iterate a point made by petec above - I have found the idle needle to be extremely sensitive to change. I am barely moving it by the width of a screwdriver blade and seeing differences in mixture.