I HAVE A CR80R IT IS A 1980 AND I BLEW THE ORIGHINAL PISTON TOOK THE ONE OUT OF THE DS80 IT FITS FINE I THINK IT HAS GOOD COMPRESSION IT SUCKS MY THUM IN AND THEN BLOWS IT OFF IS THAT GOOD OH MY OLD PISTON HAD 1 RING THE NEW PISTON HAS 2 RING WILL IT WORK PLEAS HELP ME AND I TRIED TO START IT ONCE WHILE PUSHING IT AND IT SMOKED AND BACKFIRED I DONT KNOW IF IT WAS STARTED THO IT DIDNT SOUND LIKE IT BUT I WASNT PUSHING IT ANYMORE I WAS RUNNING WITH IT PLEAS HELP ME PLEAS

 

hey. you should do a compression test because it might not have enough compression to run. if its backfiring the timing might be off on the flywheel. if the flywheel key is sheared it will cause it to backfire. also you might have a bad plug. try that and see if it runs. the piston should work as long as the rings seal up good.
Melvin