The electrajet has a speed 380/motor with a geat box. It pulls about 9 amps, as I recall. If you put a 5 amp speed control on it you will fry the speed control.

I don't think a two cell series li poly set-up can put out that much amperae, but I could be wrong. You would set up a 2S2P pack which is made of 4 cells. Two packs each with two cells in serial. Then you put those two pack together in parallel.

Now, the Electrajet normally runs on 8 nimh or nicad cells. That is 9.6 volts where a two cell Lithium is only 7.4V, I believe. So, you will be under voltaged. You may not get enough umph to fly the plane well.

I have flown mine on an 8.4 v 7 cell pack but it really wants a 9.6 pack.

The closes step with li would be a 3 cell pack for about 11 V. That might be a little high for the motor, but I think it can handle it. I believe the speed control can take to 10 cells which would be 12 V, so a 3S2P set-up would be optimum, in my estimation.

I have never tried it.