First, get the safety switches out of your mind, they are good and working properly. This manual may help.
https://drive.google.com/file/d/0B6NaqjIxWV1ySkZjTTA5TGltZEE/view
We have to find out if you have a fuel, spark or compression problem. Go through these tests in order and report back. Even if you did these before, I want you to check everything again. An assistant will help.
1. Check to see if you have spark on both cylinders. If you have spark on both cylinders, we know the ignition system is good.
2. Check to see if you have fuel getting to the cylinders. To do this, set the throttle control on CHOKE and turn the engine over at least ten revolutions. Pull both plugs and see if they are wet or dry.
If both plugs are dry, you don’t have fuel getting to either cylinder. If one plug is dry, no fuel is getting to that cylinder and you will need to check valve clearances on that cylinder.
3. If you have spark and fuel two both cylinders, I would then check to see if the flywheel key is sheared. Your plugs may be firing at the wrong time. Your option to do this. You will still need to check the valve clearances on both cylinders to make sure they are in specs.
How far you go is up to you, report back with any results.