HI, first time user. I had just purchused a ktm 65 for my son he loves the bike ,but we seem to have a few problems.1. i was told to mix the fule 60 to 1 but it seems that after he rides the bike i shut off the gas put the bike away ,the next time he goes to ride it it files a plug on every second ride . He rides the bike hard!! IS there anything we are doing wrong or any ideas ? after looking at the plug i do see a little oil on it. So dose that mean the mix has to much oil or is it something else.