is it a good idea to reuse the bearing or buying new ones when say your installing new pistons... or maybe i should say can u re-use them wihtout having any major engine probs???

 

It's always a good idea to replace the bearings. Technically you can re-use them if you inspect them and they check out as within service limits, but you might as well replace em since it's not like you get a chance to open up your motor on a regular basis.