vmf214

I just purchased a 2002 YZ250F, It is my first bike I have been sharing my son's 1979 XT500. He was able to kick it over with no problem when we test rode it. it runs really good. The problem now is that it is extremely hard to kick now we haven't been able to stsrt it at all by kicking it, we had to jump start it, any ideas on what might cause it.

Thanks Jim