The engine did not stop direct after shut down

Please click on the below links and read the forum posts that discuss the same issues and provides possible solutions. 

https://www.rotax-owner.com/en/912-914-technical-questions/4635-engine-won-t-shut-down?start=0

https://www.rotax-owner.com/en/912-914-technical-questions/4260-ignition-module-won-t-shut-off

Perhaps the idle is set above the cutoff point.They seem to start easier also with a lower setting too.

I would suspect that you may have a fault with one or both of your ignition modules. I would disconnect the plugs from one of the modules, run the engine and then see if it can be switched off normally. Repeat the experiment with the other ignition module disconnected. This will tell you whether you have a problem with one of the modules.

It would be worth checking that the ignition kill wires are both shorted to ground quickly when switching off the ignition switch. Just use a multimeter and measure the resistance to the chassis or battery -ve terminal.

Had similar problem...was due to broken ignition ground wire.   Could also be too rich, or idling too long before shutdown putting hot carbon on the plugs.

Usually when the engine won't shut down it is because of either a bad wire or just a loose wire connection on the back of the switch that grounds the engine. Remove the switch or panel and tighten all wires on any ignition switch whether it is a flip switch or keyed rotary switch. If that doesn't work check the two white ground wires out on the two ignition modules and make sure one isn't broken or pulling out of the plastic connector.