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| This is my recommended setup for any YS engine for any heli application. It is a very flexible yet convenient and simple way to take the mystery out of the YS's unique fuel system. The YS engine's use a crankcase pressurizing system that is different than most muffler pressurized fuel systems used by other manufacturers. It is possibly the most reliable fuel feed system in use to date. There are a few unique features to this system that need to be pointed out. First; because it is a crankcase pressure system, the hole in the muffler where nipple that supplies muffler pressure to the fuel tank needs to be plugged, usually with the manufacture supplied screw to eliminate fuel and oil leakage at that point. The second important feature is to NOT change the length of the short line that connects between the rear of the engine and the YS check valve. The reason for this is that YS specs their check valves to work best at that point. This has to do with pressure generated by the dowstroke of the piston, and YS has calibrated the cycling of the check valve to work best at this critical length. Usually 35mm. You can replace that piece of fuel line with your brand; however be certain you make it the recommended length which it states in the owners manual. The YS check valve MUST be orientated to allow pressure to flow TO the tank. They are marked and you can verify their direction by blowing through them. Next since this is a pressure system using a check valve, there is no way to relieve the pressure. What this means is that unlike a muffler pressure system which is open to atmospheric pressure all the time and will NOT maintain pressure; the YS system needs to have a way to release this "stored" pressure or fuel will be forced out under pressure and spray all over you or your heli. To do this I add a "tee" into the pressure line which attaches between the check valve and the fuel tank vent. The "tee" simply makes it convenient to locate a third line anywhere on the heli to be used for fueling and defueling. It can be whatever length you require for you particular application. I usually run this line to the back and bottom of my heli's where I can get at it and also so when I am fueling, any overflow can run onto the ground away from my heli. When fueling and defueling THIS IS THE PLUG TO REMOVE FIRST TO PREVENT THE FUEL SPRAY DESCRIBED EARLIER! It only takes once to be reminded which plug is to be removed first. Finally check your complete fuel system by cranking your engine for about 10-20 seconds with your starter without the glow battery attached. You should see the fuel tank bulge a slight bit and it should maintain its pressure until you release it by removing the overflow line plug. If it doesn't you will need to find your leak otherwise your engine will not run properly. This is the most common reason a YS engine won't run properly. You must not have any pressure loss anywhere in the system. Also do not kink your fuel lines or have any sharp turns. Smooth, even turns with your fuel line always work best no matter which system you use. With this setup you will have a very easy to use, clean and reliable YS setup. Rick Klages rick@heliproz.com |
