...but i saw that my solenoid could handle up to 240 v, and as far as i know more v, more powerful kick!
You read the datasheet like the Devil reads the Bible
For 240V, you can do a short pulse pulling the plunger 2mm
I'm thinking about using this step-up chip
but i don't know the circuit(where to connect the pins)?
It's all in the datasheet, just read through it.