Stalls?

[davidcl]

Recently I developed a slow knock so I put premium gasoline (Octane Rating 93) in the tank. Since then, it does not stay running with the choke off when cool, backfires, and it sluggish off the line. I checked the spark plugs and they were black. Should I run it dry or drain the tank? Also, have I damaged something and do you feel the problems I described earlier have to do with the high octane fuel or an unrelated issue I am not realizing?

It's a shame that I'm having problems so early after buying the bike.   

Thank you.

[MarkusN]

It's unlikely that the premium gas caused the problems. More likely she developed a problem which you tried to solve with the premium gas, but didn't, and the problem got worse.

[Egaeus]

Check the oil.  Often, a knock is a sign of low oil. 

If it is low on oil, and won't stay running, it could be a bad sign.

[davidcl]

As a quick update: moderate amounts of blue smoke are coming out the tail pipe. Looks like it is burning oil now.

Thank you.