I think in this case I would pass $chan to the alias...

Code:

on *:TEXT:!start:#test: _start
on *:INPUT:#test: if ($1 == !start) _start

alias _start {
  echo -a I can see both $network and $chan here
  .timer 1 5 _test $chan
}

alias _test { echo -a but I cant see both $network and $1 here }