Which big bore would be best for duning. I want to build a fast bike that is reliable and wont give me any headaches. Which companies out there should I stay away from? I have been thinking to just bore the stock cylinder and get a crazy port job, 310, 330, 350, 370, and all the powervalves out there...which is best? Pros/cons. Thanks.

 

why not start off with a 310 or 330 and you can always work your way up to a 350.

ESR or Sandtrix (OK)

 

If you really want a lot of power you could call mp racing and look in to a polanda motor.

 

I've always heard good things about ESR.

 

The ESR 370 apparently puts out 72rwhp

 

my friends mom has a ESR310R... i love it the power is perfect... i highly recomend it...

 

i would go with a esr 310

 

If your going to get a 310 (294cc), then go with the 330! Its only like 50 dollers more, and has WAY more patential.