Hard starting

Bikes up and running now thankfully! So don’t need any help with that but here’s something strange I found.

So my bike randomly stopped about a month ago due to an electrical fault. I managed to fix it (ended up being battery decided to die randomly)

So the bike had been sitting, when I tried to start it after sitting for a month it kept chugging but no life. I plugged the exhaust with my hand and i got a much more promising noise, then all of a sudden it started.

Anyone able to explain why that might have helped?

Fuel in the engine may have evaporated while it was sitting so it needed to turn over more than normal to get it to fire up. Not sure that restricting the exhaust helped at all.

You’re creating a richer fuel mixture.

Restricting the exhaust increases the exhaust back pressure which in turn increases the fuel:air mixture by slowing down the airflow through the engine. Its pretty much the same effect as pulling on the choke on older engines but in reverse. Instead of restricting the airflow entering the engine to increase the fuel:air ratio it restricts the airflow exiting the engine.