what size outrunner ?
 

How big does a outrunner need to by to have the same amount of tq as an stock zenoha 26cc gas engine ? does it have to be in the .150size or could it be smaller ?

Thats a fun mathes question, try this:

1) Figure out how many horse power or watts that zenoha produces?
2) using some fairly straight forward maths you can find out how many watts (and therefore electrical horse power) any given motor can produce.

According to my magic scrap of paper and notes learned from BrianG, the following equations should be most helpful:

Torque x RPM/5252 = Horse power

Watts = volts x amps (we should all know that I hope).

Horse Power = watts/746

Torque = 1352/kv x amps

Beyond that, I'd you need something equal to a big fat lehner 22 series motor in terms of power output...