Does anybody know where I can get a big
bore kit for my 250x. If so, how big
can they be taken to and still be
reliable?

 

Try TC racing Tom Carlson i have a 95 300ex that is punched out to a 405cc that is maxium bore for a 300ex maybe a 250x can go as high as 350 or 365 kit i am not sure. also remeber that once you get the motor work done you will have to run some vp fuel i am running vp114 its about $7 a gallon. The motor work on the 405ex cost around $2500
Alex

 

Sure, there's still lot's of stuff available for the 250X -- since it's basically the 300EX with a little shorter stroke.

As far as bore kits go, you can do 259cc without re-sleeving. 273cc with a different sleeve, but no case machining, and 288cc with re-sleeving and case machining.

Most of the time, people wo go to the 288cc kit do a stroker crank at the same time (since you have to split the cases for this bore kit anyway) - - you end up with 352cc with the bore & stroke. This is a good, reliable setup -- I've seen these run for years with no problems.

The bore kits can be obtained from White Brothers 714 692 3404 (the Wiseco kits are cheaper than the JE kits, but the JE kits seem to last longer). Powroll (541 923 1290) offers the bore kits, the stroker, and other parts for the 250X. Curtis Sparks does bore kits, strokers and other parts (805 872 4343).