YS 120 SR, Starts- but when you go to spook up it stalls.

[KingJoe]

There are 3 guys at the field that have 120's that run fine, and the same guy's have 3 seperate motors (in seperate heli's) that start fine, but will stall every time when going to spool up.
We sent one engine into Richard at YS, but I am afraid with a bench test, this will not show up.
Enya 5 Plugs
Cool Power 15% YS Blend
Needles-
High 1-1/4
Mid- 1-3/4
Any Ideas?

[Kneedragger75]

It most likely needs more fuel. Have you tried tuning it? Add a few clicks of high needle,
try spooling. Does it get better? Just because the needles are at "factory settings"
does not mean it will run properly.

[Kneedragger75]

All 3 needles need to blend into each other for true smooth operation. I bet with some experimentation you will hit on it.

[KingJoe]

We have 3 guys that know how to tune having the exact same problems.

The one guy took the needles completely out, and it made no difference.

YS has some type of issue, and it is not a field tuning problem.

We were told to take regulator off of good running engine, put it on bad running one to see if it makes a difference.

I do not want to spend 4-6 hours on the bench to find out what I already know- it is some type of YS problem.

NO WAY do the guys that I am talking about have tuning problems on one, and a strong running engine on another.

A little more than a coincidence to me.

[600bob]

If it just up and dies as you open the throttle I would say it's lean on the low end screw.

[Kneedragger75]

Perhaps a post in the engines forum will get some other 120 users to chime in.

[KingJoe]

There are 3 guys at the field that have 120's that run fine, and the same guy's have 3 seperate motors (in seperate heli's) that start fine, but will stall every time when going to spool up.
We sent one engine into Richard at YS, but I am afraid with a bench test, this will not show up.
Enya 5 Plugs
Cool Power 15% YS Blend
Needles-
High 1-1/4
Mid- 1-3/4
Any Ideas

[KingJoe]

We have 3 guys that know how to tune having the exact same problems.

The one guy took the needles completely out, and it made no difference.

YS has some type of issue, and it is not a field tuning problem.

We were told to take regulator off of good running engine, put it on bad running one to see if it makes a difference.

I do not want to spend 4-6 hours on the bench to find out what I already know- it is some type of YS problem.

NO WAY do the guys that I am talking about have tuning problems on one, and a strong running engine on another.

A little more than a coincidence to me.

[latte]

Every YS120 I have heard of, needed quite some richening on the idle-needle before it would run properly. Including my flightbuddy's which is running totally awsome now.

[Blink 182]

Do you have good fuel pressure?

[rcflier1]

sounds like my 91. it idels fine, but as it hits 1/2 throttle it quits instantly. i gave up and bought a new engine, which is fine.[ the problem engine came in a used heli]

[Jermo]

get the YS manual and follow the directions. In addition one tip I found on my YS 61 that wasn't in the manual is having a fuel cutoff on the carb line. Keep the fuel cutoff on at all times unless starting/running and vent the pressure after flying. This keeps the engine from getting flooded. For me it was getting the engine warmed up, setting the high needle, mid needle then idle. Tweaking them in that order.. someone else was helping me but it made sense after he explained it.. the real key to getting idle and transition was not having the motor flooeded..
Jer

If you find the engine idles fine but won't transition to the different needles it's typically a wrong setting. Start with the factory suggested settings and get each working first and in order.

[Glenn Goodlett]

Mine does the same thing. I tried a Enya 4 which did not make any difference. Now I pulse the throttle quickly up an down to get it over the hump, then it is fine. Seems like it is more of an issue when the motor is warn. I think if anything it is too rich because if I leave the glow igniter on it spools up with out hesitation.

[wacojoe]

Make sure the check valve is not installed backwards. You gotta have the constant tank pressure for that motor to run perfectly. I have forgot to hook the tank line up after fueling and had similar results. After a few try's I did get it to spool up and then in the middle of the flight it up and died on me, and was forced to auto the heli in. I then realized I had forgot to hook the tank pressure line up.

[stics]

Just spent a few hours at the field with mine doing EXACTLY the same thing. On mine, the idle needle was way too lean from the factory. After tuning that, was able to spool up just fine

[jwatts007]

My idle needles on both of mine are 55 minutes open, both spool up fine, idle can be lumpy but then I am using OS no 10 cold plugs.....

[Steve Graham]

Just to rule this out. Put a tank of good quality 30% fuel in one of them. My os 91 did this exact same thing on 20%. In over a year an a half it's never done it again since going 30%. You might also try a plug with a different temp rating.

[whittb]

I am having a similar issue. I can run the Enya #4 fine, but The Enya#5 will stall every time I try to spool up. Does not matter if the motor is cold or warm. Idle needle adjustment makes no difference.

The Enya #4 does seem to make the motor run warn during flight though.

I also tried to remove the spring form the one way valve as recommended by a Rep, but I did not like the results. The motor will continue to run at 25% or more after you shout the throttle off. Not a fun experience on a 700 class heli.

I see a lot of posts about the Enya #5 being the preferred plug for the YS120. So I have to believe there is a way to make it work for me. I am beginning to wander if the check valve spring rate is inconsistent. This would explain the rough idle.

While I have built and flown 3 50 size nitro helis with no issues, I found the YS120 to be a completely different beast.
Tons of power for my 10.9lbs Trex 700N DFC.

[ledfoot]

I've been having this same issue with my YS 120 and was almost ready to call it quits. I called YS yesterday and spoke with a tech by the name of Richard. I explained the issue to him and he suggested that I keep my glow plug lit until after I spool up into a hover since the low needle had to be run very rich.

I installed a Gryphon Auto Booster last night and it allowed me to keel my glow plug lit using a switch for as long as I want. This has made a huge difference in getting the engine tuned because I no longer have the engine cutting out while walking to the flightline.

Once I had the midrange needle set lean enough, I also no longer had the issue of it cutting out during spool up as well.

I want to thank Rich from YS for taking the time to work out the issues with me and for providing excellent service.

....Mike

[Fang]

Gday guys, I know this is an old thread, but just to help someone! I had the spool up from idle issue's from new and finaly had that problem solved after the guys from a larger heli club sugested I change the one way valve for a new one! Completely diffrent engine, was also going lean at wot, it solved that issue as well! I think Ive had a couple new check valves that have been alot of my problems. Just in the process of new ring and gasget set, and hatoir O rings replacements rebuild to help the leanish mid range.
Rolf