i just want to know if a xr70 head and piston will fit on an xr50 and if soo how much more power does it get??????

 

you will need the 70 cylinder also, little more power, you would be better off doing a 88cc kit, if you use the crf70 head get an 88cc cylinder and "race head" piston, you will need to change your front sprocket to 15t, you will need an hd clutch and while you are there you mine as well do a hv oil pump.