rocket in the rough?

Hello i was wondering if some one could tell me if a 91cr 250
with bore kit to 330? will it need re jet and will fuel ratio and power band, will be changed ?less on top end?
it is a trade I am thinking about
are there any things to check on a water cooler units
no oil in water oil in water check next
starts up easygoes to wheely ,then starts to load up
if you back up on throttle , it smooths out
could carb be worn a bit or bore change tune in how do I check?
does it have reed valves ?
if it does and they are dirty, will it affect all rpm areas
compression 145 psi.at normal run temp.?
is this a good set up ???????I have seen nightmares with hand me downs
with a after market pipe and and bore run like crap and no one could fix them
is stock pipe better for allaround use
is any body running a 330bore??is this a rocket in the rough??????
Thanks marcos

[slickwill]

It will definitely need a rejet. With a bore that much bigger it is going to need more fuel and more air. Open your airbox up in anyway that you can then rejet to slightly larger sizes to give the extra fuel needed. It can take a lot of work to get everything to work better together. You probably won't want to go back to a stock pipe because that is going to choke your airflow. As I said earlier a bigger bore needs more air and fuel you have to give it both and you have to get it to the right ratio. Take it to an experienced tuner and they should be able to get it running right.