ok so i recently bought a 00' 400ex with many aftermarket parts on it and im pretty sure the previous owner rode it on the track a lot cause its set up for racing. he was not the first owner and the guy that had it before him did all the work to it. the 2nd owner (guy i bought it from) didnt seem like he knew much about the engine on it and told me that it was not bored out at all when i asked him. i do know he ran 91 octane in it and its open airbox and has a pipe on it. What i wana know is if the motor is bored out at all or if the bore on it is stock. if someone could tell me how to check without bringing it into a shop, that would be great.

 

u got a buddy with a complete stock one?? ride his then ride urs... if there is a difference when it is topped out u may have a bored engine...

 

yeah my neighbors running a stock one with just an old fmf slip on. ive rode his before and it seems to hit the same speed as mine does when i get to the top of each gear. my bike does have more torque on the bottom end though. im thinking cause im running with a white bros pipe and an open airbox.