Has anybody installed a bigger motor in these little hydros. The motor in it now is a 20mm by 40 2600kv

Oh yeah. I had a Tenshock Micro Hydro that had a 2040 size motor and swapped it for a 28mm and it was like a rocket, but it couldn't handle choppy water at all. It really liked glass. Had to mod the motor mount, change the esc to a 60A and change couplers. It was very fast, but I can't say it was any more fun (worrisome) that the stock motor to be real about it.

Thanks sundogs for the return. How much faster did the 28mm get you. And the motor was a 28mm by ?

It was [link=http://www.hobbyking.com/hobbyking/store/__8594__2848SL_3900kv_Brushless_Inrunner_WaterCool ed_.html]this 3900kv motor[/link] from HK. Lots of power. I use the same motor in an ABC Jet SKi also with good results. I've never gps'd it, but I think the upper 40's would be close. Maybe low 50's. It was quite exhilarating for a little boat.