solarviper

My Feedback: (139)

i have a YS 120 nc and when i start the engine up it starts pumping air bubbles in the fuel line from the regulator to the card,the engine is producing pressure in the tank but the air bubbles are making the engine run lean and surge real bad at idle, any ideas?, thanks in advance

MajorTomski

Kinda normal for a lot of YS's. What nitro content are you using?

Newc

Suggest that you post on the YS manufacturers direct rsponse forum.

Richard L.

My Feedback: (24)

Those air bubbles are normal. That's why the factory supplied line is solid so you can't see the bubbles.

loughbd

You have a leak somewhere in the system. Mine did the same thing. It was the gasket on the regulator

solarviper

My Feedback: (139)

i use coolpower 30% heli fuel

solarviper

My Feedback: (139)

how can they be normal? my engine will not run corectly, thanks

nonstoprc

My Feedback: (90)

If the tank can hold pressure, then it is likely the fuel delivery line could have some blockage, or some rubber seals are worn off. You may consider sending it back to YS service center for a check up.

loughbd

Funny, there are no air bubbles in my fuel line. Bubbles are a no no and lead to lean running.

Hobbsy

My Feedback: (102)

As Richard says, they are quite normal, I have two .53 FZs and a .91 FZ and just sold a third .53. all pass bubbles to the carb. Your engine has some other malady.

Richard L.

My Feedback: (24)

All of my YS have some bubbles in the blue line going to the carb, and all of them run great.

loughbd

And NONE of mine do. Not bubble one.

Texan2

My Feedback: (4)

Richard, I am currently bench running my new ys110. I think I've got is close as I tying to get the low speed to hold on idle reliably. It will quit after about 30 seconds idleling without the glow at around 2000 rpms. I can keep it running if I occasionally raise the throttle a little but then it seems to load up. Is it common to have fuel dripping from the carb in between runs? The top end is turning about 10,000 rpms with a 14-7 APC prop; 1 1/4 turns out. I'm not sure which way to go on either low or high end. I'm also having a problem with the muffler in that I'm going to have to cut a big hole in the cowl to use it. The engine is pretty loud without it. Do you have any suggestions? I'm using Byron's 15-18 fuel.

Thank's Carl 409-658-2678, Beaumont, Texas.

Richard L.

My Feedback: (24)

The engine is still new, so the low end might not be rock reliable yet. Give it another tank and then "open" up the low end just a hair to lean it out. As for fuel dripping out of the carb, close the regulator screw 1/16 of a turn at a time until the dripping stops. Get a tach and take the high end up to max, then back it down by 300-400 rpm. 1 1/4 turns out seems lean to me. By the way, the 14-7 prop is "WAY TOO SMALL" for the YS 110 to swing. My OS 91 four stroke can swing that prop at 9600 rpm. Also try YS 20/20 fuel.

loughbd

A 2000rpm idle is EXCELLENT and with that tiny little prop, unbelievable. YS's love YS 20/20. Funny name for a fuel. Gee, I wonder why they call it that?

Build-n-flyer-RCU

My Feedback: (4)

Carl,

I am going to agree with Richard here and add some thoughts. The prop is way, way too small. Install an APC 15x8 or 16x6 before doing anything else. Your small prop won't provide enough load on the engine for it to run right. With the bigger prop find the high-end peak and then go back 2-3 clicks, not enough to reduce the RPM by noticable amount but enough to make sure it is not too lean. You should find that you still get 9,500 to 10,000 RPM with the bigger prop. If it won't turn more than 9,000 RPM then something is wrong.

Run 20/20 fuel or 30% heli. I run nothing but heli fuel in my YS's.

The idles on my 110's have all been great right out of the box and the idle quality should not be affected much by the regulator setting. Remember that the idle adjustment screw works backwards from most, clockwise to richen, counter-clockwise to lean. It is not at all a sensitive adjustment. You may also want to check the valves.

Some leaking from the carb between runs is not unusual but if it is pouring out then something is wrong. You can try turning the regulator in a bit as Richard suggests and it may go away.

If you can't get a good idle and/or fuel pours from the carb then I would send it back for service. I've only seen one new YS engine that wouldn't idle correctly at our field. After servicing it now runs like a swiss watch.

I run straight pipes on most of my YS's, you can get them from Central Hobbies. If you are concerned about noise then Central hobbies and Performance Specialties sells exhaust fittings and mufflers for YS that you may like better than the muffler that comes with the engine.

As for bubbles in the fuel line, as long as the tank is holding pressure then bubbles won't make a YS engine run badly. And if the tank doesn't hold pressure then the engine will not run up to RPM no matter what you do.

Walt