move to a 250 smoke or 250 4 stroke

as of now my 125 2stroke dont seem to have the power i need
me and my son ride lots of trails which the 125 works great .but when we head to the coal hills for me to climb on the 125 i need to kill it really hard to get up some big monster coal hills.my ? is should i buy a 250 2 stroke or a 250f 4 stroke.i like the light weight of my 125 so i was thinking a 250 smoker would be the thing to buy sinsce it would be double the power my 125 has and would be just a slight more weight than my 125.i would think a newer 4 stroke bike would be much heavier but have more tourqe than my 125 . what i am looking for is something to climb with where i dont have alot of runway to start with . like i said some hills i have to climb in 1st gear on the 125 which is killing the bike.

For trails i think that smoker would be better,250 4stroke has just more low end than 125 smoker.