Trying a new Motor
I got my Slash PE 4x4 a few weeks ago and have been getting it dialed for the local track. Tried the stock Velineon system on 2s and 3s lipo, and I found that on 2s the truck is very fast and the 2s gives a good balance between power and weight. The 3s was more powerful, but harder to control and added extra weight, which impacted handling. That being said, now I am going to try a bigger motor, a TeknoNeu 1509/1.5Y which is a 2400kv motor with a can that is bigger than a standard 540 but smaller than what would be used in an 1/8 scale buggy (a 1512 or 1515 sized motor). A larger motor on more voltage should provide plenty of power and run very cool. I also have a Castle Creations CS-5700 motor and a Tekno Neu 1512 2650kv motor I want to try out as well. The TeknoNeu 1509 setup weights 5oz more than the stock Velineon system.
try playing with the gearing. if you said you were having weight problems with just the 3s (which sounds kinda wonky to me) then you are going the wrong way. (adding more weight)
As I mentioned the stock system works fine on 2s, but runs a little hot on 3s. Yes I could lower the gearing to get cooler temps, but I would be at a disadvantage against the other trucks I race with (open class, Slash 4x4's on 3s, Jammins and Ofna's). I am a racer and to be competitive I have to gear up to maintain the same speed, and as I mentioned, stock motor on 2s works fine (fast enough, runs cool), but with a larger Neu motor with less kv and more volts I can gear higher for more speed and it still runs cool. I normally race 1/8 brushless buggies/truggies and this setup works well. Since I have the motors available I don't see why it would hurt to run different motor/battery combo's to see how they perform. I currently run a Neu 1509 in my Jammin and it runs great, just thought pass on my observations for on how different setups work in the Slash.
Neu 1509 motor compared to a Castle Creations 5700kv motor. Neu is bigger, has more torque and runs much cooler at the same speed.