Your problem is not your shutdown procedure.
I know it's an old topic, but I'd like to chip in on the highlights in BOLD I've just been breaking in my YS96SRX and had issues with getting my Align starter to start the engine. The trick for me was to initially clamp (stop, and assure no fuel flow) fuel from entering the engine during engine shut down, and then REMOVE the pressure from the tank. Open the throttle (carburetor) to max. Dry crank the engine as soon as possible (1-2 minutes after shut down) with the starter for 2-3 seconds. Later on (after maybe 3-5 fuel tanks of run in), I'd shut down the engine with "normal" throttle cut on the remote, but FIRST thing to do as you stop the rotor blades, relief the pressure in the fuel tank AND stop fuel (clamp) from entering the engine. You want all residual fuel (or almost all) to exit the engine, after shut down. It all gets more and more smooth and "normal" after break in. BUT, ALWAYS, ALWAYS, relief the pressure from the fuel tank (fuel line coming form the regulator at the bottom of the engine) and clamp (cut off) fuel line from the fuel tank going to the engine. Always make sure no fuel gets pressured into the engine during refueling as well. When refueling the heli, make sure you're no pressurizing the fuel tank, by relieving the pressure in the tank after (or during) refueling. That's it from me.
It is the starter.
I gave up on the Align starter years ago when it would not start my OS 91HZ-PSS engines.
The hammering and stalling happened on every start. It was a crapshoot and embarrassing.
The eHeli guys ribbed me mercilessly when I couldn't start the engines without loosening the glowplug or some other BS workaround.
I even tried jerry-rigging a 4S LiPo - and the relay would weld closed and it would not shutoff
The "solution" is to use a standard RC 12v starter with the helicopter-extension wand. I use a 3S LiPo stuck to the side.
It is almost 20 years old and has stated everything from an Enya 45 to a YS 120SR-X.
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