Am in the process of tearing down a mojave, '87 250. looking for input on bigbore #'s, and also any other advice you may have. looking to be in the 300-350 range

 

To get the most accurate information I would call one of the motor building shops, (TC Racing, Powroll, Curtis Sparks Racing, Four Stroke Tech) I know for the 1999 season Four stroke tech bored Todd Knippenbergs mojave out to a 410cc. I don't how reliable that has been but you could call and ask.