Jet jam brushless

[coltons05]

I have a jet jam I put a brushless system in and a new coupler to fit but when I hit the throttle it shakes and goes slower then stock, idk what to do

 

[tntpoof]

well with no info on this . oh and a double post wow that will get you answers faster.
what was in boat b4? turns kv so on also battery size n type.

 

[WVNed]

Tazer 390 Motor 22T​

7.4V 1500 mAh 2S Li-Ion: Jet Jam

It's a little jet boat.
If it is vibrating something is loose, the shaft is out of alignment or the prop is out of balance. As long as it is vibrating it wont make any power.