first, 170kg is... well I don't know seems low...
take 40 for each small'ish teen and 80 for an adult, plus roughly 40 for the kart...
that's already 200 kg;
for the ease of computing let's stick to that for now.
let's take bad acceleration
Fa = 1.2 * 200 kg * 1m/s² = 240 N
and let's say you want to reach something like at least 20 km/h (5.56m/s)
so you end up with 1335W of power you'd need to get there.
as you can see.. that motor is not exactly powerfull enough.. okay you'll drop the acceleration a bit and it'll be alright.
BUT in that case, you will have troubles climbing even the slightest inclination.
So the motor is on the weak side to say the least.
You'll not be happy with the result I'm afraid.
And the wheels will pretzel on you, going straight is not an issue, sideloads are
(a sharp turn, a bump in the road or hitting a curb... those things)
You can try, but be carefull, being ejected off a kart even at only 20km/h onto the pavement might not be pretty, so at least take care that the kids are wearing some protection while trying
'sid