Bad compression. Like wont start bad compression is around 80-90psi and below. My banshee is at 70psi and needs a rebuild, it wont start.
100-110psi is ok compression and 120psi and up is good compression for a stock motor.
You are going to hear all kinds of numbers but from my experience those numbers work. Ive rebuilt a couple blasters and will be rebuilding my banshee soon.