Though a timing belt and chain perform the same job, there are some differences in their components, which make it necessary to know which one your engine has.

[Dan] wanted to learn a bit about solid state ignition in engines; to get started he needed ... detect a spinning magnet on the crankshaft for timing, and a transistor and battery to fire the ...

Switching from butane to a liquid fuel ... the valves aren’t adjusted properly, or any number of other problems. In this case it seems to have been caused by improper engine timing.