anybody have experience with the 350x big bore and stroke to 430cc? hows it perform compared to normal 350x motor, what pipe should i go with for a 250x/350x conversion?

 

I have that kit installed and it runs great. The engine pulls real hard through all six gears. You do not have to stroke the engine, just resleeve it. I have a 12:1 90mm JE piston, full-race cam, full port in a 250x frame. I have modified a stock 400ex head pipe to work with my WB carbon fiber exhaust.

 

Have you e-mailed Powroll?
www.powroll.com

 

hey burden7, how much did all of that cost? whod you have do it for you?

 

The cost was around $1000 and I had my sponsor do everything. He does all of the work for me and many other local racers.

 

is the motor still dependable or have you had to rebuild alot?

 

I just got it finished back in Sept. and only have 2 races on it. And haven't ridden it since, on account of the weather. As long as I keep doing the basic maintenance, like change oil, clean air filter, and keep the valves adjusted correctly, I shouldn't have a problem.

 

There are many different combinations of stroke and bore which can achieve your goal of 430cc's. I personally know a few guys with just big bores to 416 cc's with no stroke and a few guys with 400cc X motors with a stroker crank and still the stock sleeve just overbored. I personally like the stroked motors better, They have better torque and no worries about the bottom ends breaking from moving a HUGE piston up and down. They can make X motors up to almost 500cc's and reliability is an issue at that point. I would e-mail someone at powroll and see what they think would be a reliable motor for the type of riding you want to do.