This group of verbs (ending in -ir) is quite small. However, there are different conjugations within this group, as you will see. Here again is true, what is true for many of the conjugations: the differences are in writing, not in pronunciation.
Example
finir
stem
fin
je finis
I finish
tu finis
you finish
il finit
he finishes
elle finit
she finishes
finiss
nous finissons
we finish
vous finissez
you finish
ils finissent
they finish
elles finissent
they finish
In this group we have two different stems, which always appears with perfectly regular verbs ending in -ir. The stem is, what is left, when the endings are taken away(-er, -ir, -oir, -re).
There are three groups of endings for verbs ending in -ir. The first has a irregular stem, the second group has a specialty: when the stem ends on an -t or an -d, it is omitted. The third group has endings like the verbs ending in -er.
Only the first group has a change in pronunciation.
