dear one thing is confirm,, it cant be repaired by you at home so u would have to trust a mechanic,,
maza ki baat ya ha that these enngines are very simple and are according to the qabaliat of our desi mechanics ,,yani maghaz ka istimal kam paichkash or plas ka istimal ziada,,, so kahna ka maqsad ya kka once its engine is opened every thing is black and white no grey portion in between,, ya tho damaged ha ya ok ha,,
with that said everything that is faulty will be replaced and bring back home every thing that is damaged and scrap it, so you will be sure that u got fair rpair and later u can post pics of faulty components for our delight,, in case that is repairable and the mechanics swindles you into buying new one u will have the opportunity to repair and store thm for rainy days,,
go to mechanic in he early morning so ur work can be done with fresh mind and completely,
tell him want it repaired before ur own eyes and also need everything faulty back,,,
btw what sort of sound is it ?
go to this thread download the last book ""Motorcycle_Mechanics_General_Manual"" and read page 144 of pdf [ 139 of book]
that topic explains how to odentify the type of problem from its sound,, this book is a gem, there are other books as well plz download and rate that thread,