Y.S. 61 SHORT STROKE HELICOPTER ENGINE

For the last 2 months I have had the opportunity to evaluate the new Y.S. short stroke helicopter engine. You will find this engine a little different from other helicopter engines that you might have experience with. You will also find this engine to be different from other Y.S. engines that have previously been made. One of the biggest things you will notice from other helicopter engines is that there is only one needle, sort of. I will explain a little later. The other thing you will notice from other Y.S. engines is that there is no longer a pressure regulator. This make the engine MUCH easier to adjust.

It will and should install into most 60 size helicopters with no problems. I installed mine in my Miniature X-cell Pro. Now the draw back to this engine. It needs and seems to only run with a hatori or similar tuned muffler. It will not run very well with a "U" shape or nitro pipe. After different set-ups with these and other mufflers, I installed a hatori muffler and it made a world of difference. One other thing you will notice about this engine is it will take a lot longer time to break in. Not to say it needs to be pampered till it does, but it will over time develop more and more power. This engine also is not designed to be a super high rpm motor but a torque driven motor. Even though it is a short stroke engine, it acts like a long stroke as it seems more of a torque driven engine than a speed engine. You will find that you will be able to increase your pitch settings with out any real noticeable head speed change, to a certain point, but as it breaks in you will be able to add more pitch because the head speed will keep increasing on you. You can run this engine on either 15% or 30%. It likes to have a head speed of about 15,500 on 30% fuel and if you use 15% fuel then it will like it some where between 15,500 and 16,500 but all of this depends upon your helicopters gear ration and how you like to fly. During installation you will no longer need to use muffler pressure to pressurize the tank. This is because the engine has a built in pressure pump. The other Y.S. engines all have a pressure regulator at the bottom of the engines that you use to set mixture with but this engine no longer uses the adjustable pressure regulator. This is one reason why the engine is easy to set up. Y.S. has also dropped the pressure from 6-8 lb. to only 2 lb. of pressure, so you no longer need to worry about over pressurizing and splitting fuel tanks. You also no longer need to concern your self with the tank location or having to use a header tank. You will have to install a one way check valve that does come with the engine. This check valve must be at a set distance from the bottom of the engine back plate. This length is called out in the instructions. This helps insure that the one way check valve will do the required work it needs to. Also install a high quality fuel filter between the tank and the carb inlet. Being that it is using a pump with a diaphragm you do not want to get any particulates in the pump. You will want to have your end points or ATV's for the throttle set at equal distances. This will help not only with the way the helicopter fly's but also in setting up the mixture.

Now the helicopter is set to go and your have set the needle to factory settings you will also notice that there is a high end fine tuning mixture needle. So far I have not had to touch it but I have played with it and find it to be a little sensitive so be careful here. It will only need to be turned a little bit, usually 1/8 rotation or less. The larger, main needle is basically all you need to set this engine. The engine has no idle needle. This is where having equal end points comes in. You will need to hover at this 50% throttle setting to set the needle. You set the needle so it will hover with the correct fuel mixture. If you set the mixture too far off 50% throttle, you will find that other throttle positions will either be rich or lean and you will feel it when flying. It can be hard to tell some times if your mixture is correct. The biggest way you can tell if your rich, is you will use a lot of fuel, real fast. Its hard some times to tell when you are to lean, you might still have smoke, ( and this engine will put out a lot of smoke ). Being that you started from the factory needle settings you will be rich. Start leaning it out till it starts to run smooth and stops burning fuel real fast then you will have the correct mixture with the needle settings. Once the hover is set and your flying around you can either lean or richen the high end fine tuning needle to set full power. Like I said you will probably not need to touch this. Another great thing about this engine is it is real smooth and is great on fuel consumption. I have not timed it but can defiantly tell that I am flying much longer on a tank of fuel. If I were to guess I would have to say about 5 more minutes worth of time.

When your done with each flight, it is recommended that you first vent the tank. You can do this by disconnecting the vent line from the one way valve to the tank. Then after this you can pinch the fuel inlet line to burn the extra fuel out of the carb and pump. You will also no longer need to put after run oil into the engine. If you elect to, do not use any oil that will desolve the diaphragm in the pump.

Good luck, I'm sure you will enjoy this engine, but you will have to give it some extra time to break in.

Enjoy - now go fly.

But remember - BE SAFE!!!! READ AND FOLLOW ALL THE INCLUDED INSTRUCTIONS!!!!
HB


Helibuf
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Revised: 27 Aug 2003 20:33:34 -0700 .