Motorcycle Repair: 2001 pw50, main bearings, pw50

Question
Hello,

I have a 2001 yamaha pw50. one day it jut stopped running, so i cleaned the carb and that wasnt it. i checked for spark and it had that. i then checked for compression, and it only had about 65psi. so i decided to put in a new top end. i did that, and then it still wouldnt start. it has about 105 psi of compression with the new top end in. when i try to start it, i hear a clunking noise in the motor. could it be something in the bottom end? any information would help and will be greatly appriciated.

Thank you.

Answer
Patrick, Sounds like it could be a bad rod? or rod bearing?.You should have checked the up and down of rod?? while you had the top end off?? Now you will have to take it apart again and find out? If it has some up and down?, you will have to split cases and replace rod ,bearing,pin,and while your in there replace the main bearings to save doing it over again!!! Good luck? Try me again. Glen