The reason I state the 2000rpm is as you said Togatoga the engine is on vacuum at 2000rpm and below. SO this is one reason that 2000rpm is the idle. The other reason is at 2000rpm the throttle barrel is closed enough that the air bleed screw is actually working because the barrel is closed far enough...that Air bleed is actually letting air past. As the barrel rotates and opens up the air bleed screw becomes non effective because the barrel already is letting air-fuel mixture past so it doesn't go through the air bleed hole. The low end adjustment just controls the size of that air bleed hole.


So if you idle is up at 2600rpm the air bleed is not really working anyway and any adjustment you make to it will have little to no affect on the mixture setting for the engine.

NOW that all being say. Once you get the engine set at the 2000rpm for tuning the mixtures then you can run your idle at just about anything you want. 2500rpm is fine. 1800rpm is fine. You want it high enough that it will not quit on you. This can be affected by the quality or the age of the glow plug. As the plugs age while running in the engine idle performance will suffer.

Another note 2000rpm is pretty low. I have seen the engine idle lower like posted above but I tend to pick 2000rpm as my rpm for idle.

An idle up mix or condition in the radio is a way around this....so you have a higher idle in the air while flying and then lower it down to a super low idle to land with. That works. With a properly set mixture and good glow plug.....You should be able to to maintain any idle from at least 2000rpm up. The engine should run there for a extended period of time and then transition like normal. This is where the YS engine excel and outperform most other engines on the market. Basically on the newer YS engines you have a 3 setting mixture. HS, Regulator for midrange and then the air bleed for low speed to fine tune the idle mixture. Properly setup I have seen engine idle at 2000rpm for 10mins and then transition perfectly up through midrange to full throttle.

Troy Newman
Team YS