Motor came with a one way check valve the instructions show go inline on the vent tube. Tryed that didn't work to well. Puttin fuel in air has to vent somewhere so it picked the fuseloge along with the fuel. What a mess. First time with ys motor someone explain the system, or just remember to unhook checkvalve before putting fuel in.
Thanks, Charlie

YS engines will not run correctly without the check valve in the vent line. Although, on a YS engine it's not really a vent line but more of a pressure line. That line goes from the pressure outlet on the engine itself and then runs through the check valve into the vent of the fuel tank. Make sure you have the check valve set so that pressure goes through into the tank, and not backwards. The fuel pickup line from the tank then goes to the fuel intake on the engine. You MUST have it set this way or the engine will not run properly. YS engines are designed to run with a pressurized fuel system and that check valve is there in order for pressure to stay in the tank.

Ken

Thanks Ken, Any advice/mods on filling the tank then? Or just like i said break it at the check valve went filling.

BTW, the fuel pickup side of the engine is the right side? Prop shaft forward.

To fill the tank you need to remove both lines. The fuel pickup side is where you fill the tank through. You disconnect the pressure side so that you can see when the tank is full, fuel will flow out of the the pressure line. If you don't disconnect both lines you will never be able to fill the tank because you need to allow someplace for the air in the tank to go when you start pumping in fuel.

Ken

Thanks Ken

All YS engines are closed circuit pumped fluid systems including the two stroke types. It cannot vent to atmosphere. As indicated by RCKen The check valve must be in the return line to the tank (The port that is normally considered the vent). This valve has an small embossed arrow on the body and this arrow must be pointed toward the tank. If not sure about the arrow just blow into both ends and it will be obvious. The pressure must be toward the tank.

Caution these systems can retain fluid pressure in the tank for long periods of time after the engine has stopped. Always unplug the check valve or a capped tee line in the main return line first before fueling through normally in the other line which is the tanks clunk to engine line. Unpluging this line first can result in a ten foot stream of fuel shot randomly long after the engine is stopped.

The best tanks for YS are either Hayes or the clunk type Tetra's. The simple precaution of wraping the tanks in a few wraps of filiment strapping tape will go a long way in trouble free operations. Most cheap no name Arf fuel tanks and copies of Hayes tanks will soon present problems weeping from the Bung plug or the exit tubes, even ruptured tank seams.

YS engines are unmatched performers as well as user friendly but they are plumbed differently and it is a big mistake to use cheap tanks.

If your engine is new suggest you not touch that big pressure regulator screw on the bottom of the crankshaft only the needle valve and possibly a slight leaning of the mid range screw after running in a bit.

John

The pictured tank is not a Hayes (far preferrable) but it shows the strapping technique.

If After running the engine the fuel overflows the engine and fills the plane then your pressure regulator is set too high. And yes I have filled a tank without disconnecting the check valve. I got a great bath both times.

Here is the owers manual from the 1.10. Same layout as the 91. http://yspartsandservice.com/pdf/FZ110.pdf

You only need one check valve. Also, make sure you use a quality name brand fuel tank. I've used Sullivan, Hayes and Dubro w/o problem, but I split a tank supplied with an ARF once. I won't let THAT happen again.

Just for clarification, looking at the engine from the front, the left nipple goes to the clunk, the right nipple goes to the check valve and the vent. The check valve should "blow" Toward the tank. You will need TWO 1/8" "T's" and two fuel Dots. Like this.. http://www.horizonhobby.com/Products...?ProdID=HAN115

One T must be between the check valve and the tank vent. The second one anywhere between the tank and engine.