When striking with my backhand (IE the hand that is furthest away from the target)I turn my hips,legs and shoulders to give the punch power.

But when jabbing with my forward fist, I can't figure out how to put the force of full body movement into it.

Oh yes you can, you just haven't yet!

okay.....how? thats the implied question.

It's hard to explain with text but I'll try:

It's easier to explain by using a specific side.
from: right foot forward, right hand forward.

torque (without telegraph) your hips in a clockwise tension while pushing the floor away and down with the balls of each foot.
let the spring loose and your arm will follow.

help me out with this one hedkikr.

If you can get hands-on instruction it could help, otherwise most people are better off trying and experimenting for themselves, than trying to follow text instruction (my vho)

OK...Kimura's method is difficult to describe - it must be seen & felt so...
(Same stance w/ R hand & foot forward):

Standard Jab (Kizami-tsuki or Maeken-tsuki) - Step in w/ your R foot as you release the Jab, Let your L foot follow (but not drag) as if a large rubber band encircling both ankles was stretched & contracted. Let the momentum add some power. You should be slightly "off-balance" in a forward direction.

(Note to kara: you're right)

Heh, there are so many ways its ridiculous. Using the half step method from xingyi works amazingly well, and it can be done on short distances. The back leg is positioned at 45 degree angle while you spring off of it, even if slightly, your front foot lands at the exact same time as your punch, creating a stomping effect in which you draw your power from the ground, your back leg moves up in half step along with the front leg to regain balance.

You can use your front foot as a pivot point, but in my case I relax my entire body and simply shoot out my arm with full mental intention. The movement becomes natural, and not only is your waist behind it, but your legs are also driving the punch. Since it all happens at once, there is no telegraphing. The rooting is there for me so I don't think much about it.