hey guys my 1989 lt250s is in the shop getting the topend rebuilt because it was smoking really badley am i going to have to break it in when i get it back??

 

A top-end rebuild usually consists of new rings if not a new piston as well, so yes you'll have to break it in again.

 

yeh its getting bored out with a new piston/rings and valve seals and so on...how do i break it in??

 

depends on who you talk to....alot of people say for the first 10hours on the machine just take it easy, don't go full throttle and/or ride it really hard. Other people say to break it in how you are going to ride it. With my back round of engine building i suggest doing the first way. You've got to let the rings seal to the cylinder wall. If you fail to do so then you will get combustion into the crankcase and have blowby.