first off mate, it would help everyone if you told us whether it was a stock UK/US board because straight away if you tell me youve got a UK stock board then youll be quick to learn that they dont have the the modes you request lol but US do
if you look in the manual for your ion and read the modes bit it will say what modes is relevant to UK/US boards
UK board has semi and rebound, if you want to use rebound however you will get dramatic drop off as you shoot at a decent pace but it will be fine at a few shots and pause, this is due to the stock parts of the ion not keeping up with the mode it is selected and so it does not function fully and drops balls out of barrel virtually lol.
hope this helps mate, and personally i would say learn to use semi before you start cheating and using 3 shot bursts and things. Start with the basics and get your fingers working well
Craig