JasonF

My Feedback: (2)

Hello all,
I have a YS120NC mounted in a Goldberg extra. It's using the stock muffler, Red Max 20% nitro/19% synthetic fuel, OS F plug, 15x10 APC prop, and feeds off a 20oz tank mounted on the cg.
I have had problems with this engine loading up since day one. I sent it in once and YS Performance drilled my butterfly and sent it back to me. No change other than the fact that now I couldn't shut the engine off. I called them to ask for more advice and they sent me a YS120AC carb barrel. I put this in and it seemed to help a little, but just the other day I was flying around and right as I said how nice it was flying it loaded up and quit at about half throttle. If I fly around from half to wide open it runs great. However if I do stall turns and other less than half throttle maneuvers it loads up and quits after a few minutes. I would like to be able to explore the low speed aerobatics with this plane but at this point the engine won't allow it. It's a shame to spend this kind of money on an engine and have to fly around wide open all the time. Adjusting the low speed via the regulator as described in the instructions just doesn't cut it. I'm past flush now and while it idles ok the mid is the problem. Does anyone have some suggestions on how I can keep this piece running through some slow stuff? thanks

Jason

Dave Shadel

Does the carb fill with fuel after you shut the engine down while the tank still has pressure in it? If so, this is 90% of your problem. Either it needs a new plunger or there is debris keeping the plunger from seating properly.
Put the regulator screw flush with the casting. The regulator screw controls ONLY the transition between low and high. It does NOT change the fuel pressure nor does it control idle or high speed settings. If the transition or mid range is too lean, turn the reg.screw counter clockwise 1/4 turn at a time until it is corrected. Clockwise if you have a too rich condition.
The regulator screw would normally NEVER move more than 1 turn in or out from flush with the casting. It sounds like your mid range could be too lean.
What plug and fuel are you using? It's very important that you run at least 20% nitro fuel and either a YS#4 or OS type F plug.

Let me know.
Dave

JasonF

My Feedback: (2)

The fuel and plug info you requested was supplied in the original post.
I don't know why you think my mid is too lean, the engine loads up and quits (obvious by the excessive smoke right before it quits). Yes, with the engine mounted sideways it does slowly drip fuel out of the carb. However the engine is always run with a sullivan double screen filter, and I don't have more than 5 tanks through it since it was at YS performance, so surely if this plunger you describe is shot they would have replaced it?? When you say plunger are you referring to the unit under the regulator screw?

Next I will try a different type of fuel, however my friend runs the YS120FZ and 91FZ (both with low end mixture adjustments) on the exact same batch of fuel as me and his run flawlessly. I think YS missed the boat with this engine as evident by the next FZ edition engine including the low end screw that the engineers forgot on the NC.

Jason

Dave Shadel

Sorry I missed it, it's been a long and busy week.
There are lots of NC's which run well so there's no reason yours won't do the same thing.
The engine should not drip fuel when pressured up. I still suspect the plunger is at fault. I'd appreciate your trouble in sending the engine back to us one more time. I know it's a hassle, but we do like to stand behind the product and the service.
If you decide to do so, please send it to my attention at the following address:

YS Performance
P.O.Box 3146
Gardnerville,
NV 89410

Attn: Dave Shadel

Thanks!

Dave Shadel

Another thought just occured to me.
It is possible that an intermittant check valve could be the problem. Swap it out with another known good check valve from one of your friends setups and try it prior to doing anything else.
If it doesn't work out, I'll need to see it.
Thank You,
Dave

Geistware

My Feedback: (16)

This may sound strange but when it loads up and dies, look at the tube between the regulator and carb and see if you see any bubbles? If yes, then your tank is foaming or your clunk is not quite right. If you don't see bubbles, then I would recommend that you try a tank or two of 30% and see if the loading up goes away.

Use a fresh glow plug to make sure that you have enough heat to ignite the large quantity of fuel.

Last, if this does not address it, close the regulator and run it without the pressure. I have done this and it works. You have less power but it still run. See if it loads up or runs OK.

JasonF

My Feedback: (2)

I did a little more investigating tonight and looked at my check valve. I have tested it in the past while I have had this engine problem and it was good, but tonight it allowed air to pass in both directions, so apparently it has died. How long are these things expected to last? I have a foremost products check valve I will stick in there temporarily but I need to get the full size YS unit in there. Dave S can you help me on this? I will try to run it tomorrow and see where things stand with the engine.

Jason

P.S. one other question, is there a set distance the check valve should be from the engine like with the YS ST2?

Dave Shadel

The YS check valves are screwed together, so take it apart and see if there's a lump of crud in it. If you can't find anything, replace it. We usually run a filter between the engine and the check valve to help keep anything out of the check valve. I've had check valves last for years, but check it periodically just for grins.
The Foremost unit will work, but they sometimes come apart when you least expect it.

There is no set distance on the check valve from the engine.

Hope we found the problem.

Dave

MarkNovack

My Feedback: (3)

This is an older posting, but I had the same trouble when mine was new.

I drilled the butterfly out a bit (don't remember precisely, whatever Rick Mattie suggested on his YS doctor page) and it helped a little bit. Then I became brutal and turned in the regulator a couple turns (well past flush) and things got better. Finally, after about 3-4 gallons the motor cam alive in all speed ranges and has been kicking heinny for about three years. I don't even treat it very well, I just feed it 30% Coolpower and it runs like gangbusters. I tached it with an APC 15-10 at about 9500 (a little more).

Dave, do you think it would respond well to a 16-8? I would like to get more propellor disk diameter for easier hovering.


Thanks,
Mark

Dave Shadel

The 16x8 should run about the same as the 15x10, but the vertical should be better.

Good Flying,
Dave