i have a magnum .91 and when im flying it performs flawless, does everything i ask it to. i think i know what the problem is but im not sure and want to make sure im heading down the right path. when im coming in for a landing and bring the engine down to an idle it will eventual will die. im thinkning i need to adjust the low speed needle a lil. im not sure which way to go with this. should i lean it or richen it, since it keeps dieing i think it needs to be richen but im not sure, if anyone can help thanks.
kyle

Kyle,

You are in the ball park, but you need to determine what the problem is.

Start from scratch on the tuning. Peak out the top end, then go rich by about three hundred RPM. Yep, you need a tach. Then set the throttle for a slow speed, around 3000 rpm. Let it run there for a bit, then punch the throttle open as fast as you can. One of three things will happen. The engine will quit, or the engine will sputter and slowly gain speed, or it will just jump without a hiccup to high RPM.. The last is what you want. If the engine just dies when you punch it, the idle mix is to lean, If it sputters and slowly gains RPM, the idle mix is to rich. There are two ways to set the idle mix. One is to set the throttle as low as you can to keep the engine running, and then start slowly leaning the idle for maximum RPM. Don't change the throttle while doing this. Once you have the max idle RPM, then go back and find tune the top end again, then repeat the idle. Once you have it so it jumps to the throttle, you are good to go

Another way is to again tune the top end, the cut to idle and then punch it. Again if it sputters and slowly gains RPM, it is to rich on the low end. Now while it is running, using a long screwdriver to clear the prop, give the idle mix a snap to the lean side. then punch it again to see what happens.

It doesn't matter if it is a four stroke or a two stroke, they both will respond the same. The two strokes can store fuel in the crank case, so the top end run up needs to burn off the fuel and get to the running mix.

Last, the idle and high end needles are a balancing act. You can get the idle mix so out of whack that the high speed doesn't seem to want to adjust right. If things don't seem to be going as expected when you start adjusting the needles, dig out the manual for your engine and see what the "factory starting settings" are. Each engine is a bit different, and some require the idle to be screwed OUT to a stop vs In to a stop for the initial setting. The manual will tell you this.

Once you have the settings as best as you can get, then you can worry about glow plugs, tank height, fueland the other common "reasons" why the engine goes dead stick on idle down. They are all valid issues, but unless the mix is right, don't worry about them.

Don

If the engine is otherwise tuned OK (transitions well, passes the "pinch" test), but can't seem to hold a reliable idle, it may be time to install a fresh glow plug.

If the engine dies right away and every time you reduce power it could be that your trim is just too low give it a couple of clicks up trim.....
If the fuel is coming from the bottom of your jug it maybe a fuel problem.....other than that I'd richen the low end a tad...if that fails...a glow plug
Good luck