would a 330 kit work for a 250x? I know it would be less cc since the 250x as a shorter stroke. I recently saw an article in dirt wheels with a 330ex. I would rahter do this than the 350 conversion because it will be easier and less weight and u keep reverse
thank for any info

 

I have a 78mm piston in my 250x (the same one that is used in the 330ex kit) I gives a total displacement of 273cc. With a stroker crank (12.7mm) it will yield 335cc. This piston requires resleving of your cylinder but DOES NOT require crank case machining. The 80mm piston yields 288cc and 352 with stroker crank. It and the crank will require crank case machining. FTZ performance (Cape Girardeau, MO 573-334-5439) built my engine using powroll parts. With a 250lb rider, on race gas I can smoke piped up, carb kitted, warriors off the line and top end with stock tires and gears. Mine is 273cc 10.5:1 compression, .336 lift 298 duration cam, full port/polish, 35mm FCR carb, sparks racing CDI box, K&N filter, 1mm oversize intake valves, supertrapp exhaust.
Hope this information helps.

 

How much did this cost u? how much can u do by yoourself? thanks alot.

 

This motor was by no means cheap, but as they say, "speed costs. How fast do you want to go." The amount that the individual can complete is minimal. The old sleeve must be bored out and a new sleeve pressed in. The new sleeve must then be bored. Port work is more complicated than making a big hole, so leave this to professionals(a bad port job can cost you power). The cam sprocket must be slotted to adjust timing and a degree wheel must be used to ensure exact timing(you don't want valves tapping your piston at 10,000 RPM). To be done right, the engine should be clayed (placing clay on top of the piston to check valve clearance). This means the engine could have to be assembled and disassembled many times. They only place I could have saved by doing it myself would have been in assembly, but FTZ does it for $125. FTZ installed a new lower timing gear that didn't want to come off and stuck me with an hour of labor. Big bore kit, cam, heavy larger diameter valve springs which are needed with the cam, 1mm oversize intake valves ($89 each), port work, lower sprocket install, assembly of motor, machining for valves, install new timing chain, and timing the motor ran almost $1750. The stock carb will NOT support this motor. You will need a new one expect to pay 150-450. A high rev-CDI will help $115 from sparks racing. A oil cooler is a great investment for any air cooled motor $150. FTZ engines are high priced but they are made with exact tolerances and are very reliable. If you have any more questions, feel free to e-mail me at: Sandric@go.com

 

whoa you have a lot in that motor

i will have only 1,000 in mine when i'm done....

call up four stroke tech