Last time I rode my XR650R was around 10 months ago (knee injury). Now if I get it started when I let off on the gas it starts to back fire. Another thing is I can't seem to get it to idle right. When I start it up I move the choke up but it soon starts to rev really high so I turn the screw next to the choke until it stops revving high but now when I move the choke to the middle position the bike turns off. I dumped out all the old gas but that didn't seem to make much difference. Any suggestions or input will be greatly appreciated.