How much faster will a Yamaha blaster go with the 240 kit?

There is a lot of unknowns in your question. Other factors as carburator,exhaust,spark plug,reeds,etc.. All of these will effect performance, horsepower and speed. I am working on my blaster now with a Weisco piston kit .040 over,Mikuni flat slide carb,FMF exhaust system, NKG iridium plug,high voltage wire and a new reed not yet determined. For more info go to Blaster forum.com.My e-mail isdlporkchop@gmail.com.