250 main sounds awful small. Check web page of pipe manufacturer for jetting. It will be for sea level and xx* temp. Compensate for your elevation & temps. You also have to add for porting, air filter, lid/no lid.
Hope you don't have one of those junk eGay cylinders, or you WILL be doing another top end. Some have been known to only last hours, some barely past heat cycles. Do you know if the cylinder and head were retorqued after heat cycles? Very important on a Blasturd.