My son's predator took a crap a while back( forgot to check the oil) anyways long story short I got to replace the jug, piston, etc, I decided to get a big bore kit off line wich promises to convert my son's bike to a 70cc wich is great being that he needs some more power and speed, not to mention the big bore kit is less than half the price as the standard parts, my question is do I have to get a jet kit? and how hard is it to do a jet kit?
get a 100 main jet & a uni filter. It is easy as removing the bowl from the carb. The main jet is in the center bottom. Flat tip screwdriver will remove it. Double check the specs on the big bore kit, most of the time to make that big of a jump in cc's you will have to change the crankshaft to a stroker.
You may want to up grade the carb and intake. 20mm on the carb to see the real diffrence. You should be ok with the stock crank on the port timing.
Ride safe