97 scrambler 400

Recently purchased a 97 scrambler 400 2 stroke got it going but seemed to be having spark issues until one day will trying to start it the bendix blew up. After taking it apart the stator was in bad shape as well. Replaced bendix and stator and the bushing in the starter for the bendix. The issue I am having is the bendix engages for a second and then there is just spinning tried the pull cord and it could probably rip my arm off once compression is built up Took plug wire off still turns for second and then tree just spins l take the plug out and it turns over fine wondering if it could be the decompression hole in th exhaust port any help would be appreciated